METHODS OF MAKING LOW TURBIDITY COATINGS AND COATINGS AND COATED ARTICLES MADE WITH THEMCROSS REFERENCE TO RELATED REQUESTS This application claims the benefits of United States Provisional Application serial number 60 / 172,283, filed on December 17, 1999, and United States Provisional Application serial number 60 / 125,050, filed on October 18, 1999. March 1999, whose descriptions of such provisional applications are incorporated herein by reference. BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates in general to coatings and coated articles and, more particularly, to methods of depositing coatings and making coated articles having low turbidity and / or low emissivity. This invention also relates to solar control coatings for articles to reduce the transmission of infrared (IR) energy, in particular near infrared (NIR) energy, while maintaining a relatively high visible light transmission and color transmitted and / or reflected substantially neutral of the coated article. 2. Description of currently available technology • Low emissivity coatings deposited on a substrate, for example, a glass substrate, are used in many applications, such as transparent freezer doors, oven door windows, architectural windows, example, commercial or residential windows, and vehicle windows, to name a few. Emissivity refers to the propensity to emit or radiate energy from a surface. "Low emissivity coatings" allow ultra-violet (UV) energy, for example, less than 400 nm, and visible wavelength energy, for example, from 400 nm to about 780 nm, to be transmitted through a window but reflect the infrared (IR) energy, for example, greater than about 780 nm. Such low-emissivity coatings are attractive for use with architectural windows, for example, since they avoid the loss of radiant heat through the window during cold periods, reducing heating costs during winter and the costs of retrofitting. air during the summer. Low-emissivity coatings, however, are not very suitable for use in warmer climates, such as the South of the United States, since low-emissivity coatings transmit a high percentage of visible light during the day that can heat the interior of the building, thus increasing the costs of refrigeration. Examples of commonly used low-emissivity coatings include metal oxides, such as tin oxide (Sn02), or dopa-two metal oxides, such as fluorine-tinned tin oxide (F). U.S. Patent No. 4,952,423 discloses a low emissivity coating of tin oxide doped with fluorine. Coatings that provide not only low emissivity, but also solar control properties, such as reflection or absorption of solar energy or a low coefficient of shade, are desirable in the warmer climates. The term "shade coefficient" is generally used in the glass industry and refers to the heat gain obtained when an environment is exposed to solar radiation through a given zone of opening or glazing to the heat gained through the same size area of a clear single cloth of 3.17 mm (1/8 inch) thickness (ASHRAE Standard Calculation Method). to the clear glass of 3,17 mm (1/8 inch) of gro-sor is assigned a Value of 1,00. A value of the shadow coefficient less than 1.00 indicates better heat rejection than clear single cloth and vice versa. Tin oxide doped with fluorine provides low emissivity characteristics. Tin oxide doped with other materials, such as antimony (Sb), may have solar reflection and absorption characteristics. Tin oxide coatings doped with antimony are much higher absorbents of solar energy than tin oxide alone. Tin oxide doping with antimony improves the absorption of nearby infrared solar energy and also decreases the transmission of visible light, characteristics especially useful in warm climates to avoid excessive heating of the interior of a building or vehicle in the summer months. In addition to tin oxide, other metal oxides used in the formation of low emissivity and / or solar control coatings include Sb203, Ti02, Co304, Cr203, In02 and Si02. However, tin oxide has advantages over these other metal oxides because of its resistance to abrasion, hardness and conductive properties. The advantages of low emissivity and solar control can be obtained by providing a coating having a low emissivity coating material, such as tin oxide doped with. fluorine, with a solar control coating material, such as a tin oxide doped with antimony, or providing a coating having mixed emissivity and solar control materials, such as tin oxide doped with anti-monium and fluorine. An example of such a coating is described in GB 2,302,102. U.S. Patent No. 4,504,109 discloses an infrared protective laminate having alternative infrared protective layers and inferential reflection layers.
-ArGB 2,302,102 discloses a coating having a single layer of tin / antimony oxide in which tin and antimony are in a specified molar ratio, and also discloses a layer of tin oxide doped with fluorine applied over a tin layer / antimony oxide. As a general rule for metallic oxide or doped metal oxide coatings, as the thickness of the coating increases, the emissivity of the coating decreases and the conductivity increases. Therefore, if other factors were not involved, a solar control coating having a low emissivity, for example, less than about 0.2, could be obtained simply by increasing the thickness of the coating to a level to obtain the desired emissivity. However, increasing the thickness of the coating also has the disadvantages of increasing the turbidity of the coating, i.e., the amount or percentage of light scattered as it passes through an object, and of decreasing the amount of visible light transmission. Such coatings may also exhibit undesirable iridescence. In particular for architectural or vehicle windows, such turbidity and iridescence are not desirable. For most commercial applications, a turbidity greater than about 1.5% is normally considered objectionable. Therefore, the ability to provide a low emissivity coating with or without solar control properties has so far been limited by the need to minimize the turbidity of the coating to commercially acceptable levels. GB 2,302,102 teaches the hypothesis that such turbidity of the coating is due to the internal turbidity produced by the migration of sodium ions from the glass substrate to the coating and proposes to provide a non-stoichiometric silicon oxide barrier layer between the substrate ofglass and coating to block the migration of sodium ions to reduce turbidity. Many known infrared reflective coatings also exhibit iridescence or interferential colors with reflected and transmitted light. Coated transparent moons, such as vehicle windows, that provide lower infrared transmittance and lower total solar energy transmittance to reduce heat gain in the interior of the vehicle should also preferably be of a substantially neutral color, e.g., gray, so as not to collide with the general color of the vehicle. As will be appreciated by those skilled in the art, it would be advantageous to obtain a coating, coated article and / or method of coating that provides a coating of relatively low emissivity, for example, a coating with an emissivity of less than about 0.2, which also has a low turbidity, for example, less than about 2.0%. It would also be advantageous to obtain a coating and / or coated article having reduced infrared transmission and / or a low shade coefficient while maintaining a relatively high visible light transmission and reduced iridescence. SUMMARY OF THE INVENTION A coating of the invention includes a first coating surface, a second coating surface, and an interruption layer located between the first and second coating surfaces. The interruption layer is configured to interrupt the crystalline structure of the coating. Another coating of the invention includes a first substantially crystalline layer, a second substantially crystalline layer deposited on the first layer, and an interruption layer located between the layers -0"first and second. The interruption layer is configured to prevent or at least reduce the epitaxial growth of the second layer on the first layer. Another coating includes a substantially crystalline first layer including tin oxide doped with antimony having a thickness of, for example, from about 1200A to about 2300A.; a second substantially crystalline layer deposited on the first layer, including the second layer tin oxide doped with fluorine and having a thickness of, for example, from about 3000A to about 3600A; and an interruption layer located between the first and second crystalline layers. The interruption layer, for example, an amorphous layer, prevents or at least reduces the epitaxial growth of the second layer on the first layer. A coated article of the invention includes a substrate and a coating deposited on at least a portion of the substrate. The coating includes a first coating surface and a second coating surface, with an interruption layer of the invention located between the first and second coating surfaces. Another coated article of the invention includes a substrate, a first substantially crystalline layer de-positioned on at least a portion of the substrate, an interruption layer deposited on the first layer, and a second substantially crystalline layer deposited on the interruption layer. An additional coated article includes a substratum, a first substantially crystalline layer deposited on at least a portion of the substrate, and an interruption layer deposited on at least a portion of the first layer. The interruption layer is configured to prevent or at least reduce the epitaxial growth of a substantially crystalline coating layer then deposited on the coated article. Another coated article includes a substrate, a color suppression layer deposited on at least a portion of the substrate, and a first substantially transparent metal oxide conductive layer deposited on the color suppression layer and having a thickness of, for example, approximately 700 Á to approximately 3000 Á. The color suppression layer is preferably graduated, with a thickness of, for example, from about 50A to about 3000A. Another coated article includes a substrate, a layer of tin oxide doped with antimony deposited on at least a portion of the substrate and having a thickness of, for example, from about 900A to about 1500A, and an oxide layer of fluorinated doped tin deposited on the tin oxide layer doped with antimony and having a thickness of, for example, from about 1200A to about 3600A. The tin oxide layer doped with antimony preferably has at least two layers of different antimony concentrations, with a first layer having a thickness of, for example, about 985 A and a second layer having a thickness of example, approximately 214 Á. Another coated article includes a substrate, a first layer of doped metal oxide deposited on at least a portion of the substrate, and a second layer of doped metal oxide deposited on the first doped metal oxide layer. The first doped metal oxide layer has a lower refractive index than that of the second doped metal oxide layer. Another coated article includes a substrate, a color suppression layer deposited on at least a portion of the substrate, a first substantially crystalline layer deposited on the color suppression layer, a second substantially crystalline layer deposited on the first layer, and an interruption layer of the invention located between the first and second layers. An additional coated article includes a substrate, a first coating region deposited on at least a portion of the substrate, the first coating region including a metal oxide and a first primer; a transition region deposited on the first region, including the transition region a metal oxide, the first dopant, and a second dopant, constantly changing the ratio of the first dopant to the second dopant with the distance of the substrate; and a third coating region deposited on the second coating region, the third coating region including a metal oxide and the second dopant. Optionally, one or more interruption layers of the invention can be placed inside the coating stack. A method of coating a substrate includes depositing a first substantially crystalline layer on at least a portion of a substrate, depositing an interruption layer on the first layer, and depositing a second substantially crystalline layer on the interruption layer. The interruption layer is configured to prohibit or reduce the epitaxial growth of the second layer on the first layer. Another method of coating a substrate includes depositing a first substantially crystalline layer on at least a portion of a substrate, and depositing an interruption layer on the first crystalline layer. The interruption layer is configured to prevent or at least reduce the epitaxial growth of a crystalline layer then deposited on the first crystalline layer. Another method of forming a coated article includes arranging a substrate, depositing a 4-color suppression layer on at least a portion of the substrate, the color suppression layer having a thickness of, for example, about 50 Á to about 3000 Á , and depositing a first conductive substantially transparent metal oxide layer on the color suppression layer, the first conductive metal oxide layer being, for example, tin oxide doped with antimony having a thickness of, for example, about 700 Á at approximately 3000 Á. BRIEF DESCRIPTION OF THE DRAWINGS A complete understanding of the invention will be obtained BY the following description taken in connection with the figures of the accompanying drawing, where analogous reference numbers identify analogous parts. Figure 1 is a side view in section (not to scale) of a coating and coated article incorporating features of the invention. Figure 2 is a side view in section (not to scale) of another coated and coated article incorporating characteristics of the invention. Figure 3 is a side view in section (not to scale) of another coating and coated article incorporating characteristics of the invention. Figure 4 is a graph of solar absorption as a function of wavelength for various tin oxide coatings doped with antimony on clear float glass. Figure 5 is a graph of the transmittance as a function of the wavelength for a coated article of the invention. Figure 6 is a graph of the wavelength transmittance for a coated article of the invention having a layer of tin oxide doped with antimony thicker than that of Figure 5. Figure 7 is a graph of the transmittance in l?Wavelength function for an article coated with and without a layer of titanium oxide. Figure 8 is a graph of color variation with changes in the thickness of the tin oxide layer doped with fluorine. Figure 9 is a graph of the color change with changes in the thickness of the fluorinated dope tin oxide layer for a coating having a tin oxide layer doped with fluorine on two layers of tin oxide doped with antimony . And Figure 10 is a graph of color variation with changes in the thickness of antimony-doped tin oxide layers for the coating of Figure 9. DESCRIPTION OF PREFERRED EMBODIMENTS Except in the operative examples, or where indicated otherwise, all the numbers expressing quantities of ingredients, reaction conditions, and so on, employed in the specification and the claims are to be understood modified in all cases by the term "approximately". In addition, any numerical reference to quantities, unless otherwise specified, is "by weight". Considering first the turbidity problem, it is postulated here that for crystalline or substantially crystalline coatings, for example, crystalline metal oxide coatings of low emissivity, from more than about 2000A to about 4000A thick, turbidity of the coating is primarily due to the surface morphology of the coating and not to factors of internal turbidity as previously thought. As a general rule, low emissivity and / or solar control coatings are typically made to be crystalline because the crystalline structure provides the advantages of better adhesion to glass substrates, greater durability and also provides faster coating growth and therefore greater chemical efficiency. Another advantage of the crystal structure is that it increases the electrical conductivity, which promotes a lower emissivity. However, this crystalline coating structure, whether formed of one or more coating layers or materials, can lead to the formation of large monocrystalline structures, for example, greater than about 2000 A to about 4000 A thick, which give place at high surface roughness or roughness and therefore high turbidity, ie, greater than about 2%. For example, to form a low emissivity / solar control crystalline coating having a layer of tin oxide doped with fluorine (F) (Sn02) on a layer of tin oxide doped with antimony (Sb), it is applied first tin oxide and antimony precursors to a substrate. Antimony and tin oxide precursors nucleate on the surface of the substrate to begin to form tin oxide crystals doped with antimony that grow in size as more precursor material is applied. When the first crystalline layer is at a desired thickness, fluorine and tin oxide precursors are deposited on the first layer to form a second crystalline layer of tin oxide doped with fluorine. In the sense in which they are used herein, the terms "doped" and "dopant" refer to a material that may be present in the crystalline structure of another material or may be present in the interstices of the other material. However, it has now been determined that if the precursor materials for the second crystalline layer are deposited directly on the first crystalline layer, the crystals of the second crystalline layer tend to grow epitaxially in the crystals of the first crystalline layer, ie, not nucleates but rather continue the crystalline structure of the crystals of the first layer to form large, elongated monocrystalline structures, which extend upwards substantially throughout the thickness of the coating, the lower portion of the crystalline structure being tin oxide doped with antimony and the upper portion of the crystalline structure being tin oxide doped with fluorine. This epitaxial crystal growth results in a coating with a very high surface roughness and therefore unacceptably high turbidity, for example, greater than about 2%. The high surface roughness has been confirmed by atomic force microscopy (AFM) and scanning electron microscopy (SEM) and is believed to be the primary contributor to the overall turbidity of such crystalline coatings because the turbidity is reduced when the surfaces are polished. Based on this new knowledge, the present invention provides a coating and method of coating that allows the formation of low emissivity coatings and / or solar control, for example, composite crystalline metal oxide coatings or multi-foot coatings on a substrate. which maintain the advantages of the crystal structure described above, but which prevent or reduce the epitaxial growth of crystals common in the previous coating processes and, therefore, reduce the turbidity of the resulting coating. A coated article 10 embodying characteristics of the invention is shown in Figure 1. Article 10 includes a substrate 12 with a coating stack or "coating" 14 deposited on at least a portion of the substrate 12, generally over the entire surface of the substrate. substrate 12. Coating 14 has an inner or first surface 13 and an outer or second surface 15. In the sense used herein, the terms "deposited on" or "disposed on" mean deposited or arranged by an -ma, that is, at a greater distance from the substrate, but not necessarily in superficial contact with it. For example, a first coating region or layer "deposited on" a second coating region or layer does not preclude the presence of one or more other coating regions or layers between the first and second coating layers. The coating 14 includes a first region or layer 16 and a second region or layer 20 with an "interruption" region or crystal growth layer 18 of the invention located between the first and second layers 16 and 20. A layer can be deposited protective layer 22 on the second layer 20. The term "layer" is used herein to refer to a coating region of a selected coating composition. For example, a layer of tin oxide doped with fluorine is a region of the coating made predominantly of tin oxide doped with fluorine. However, it is to be understood that there may be no distinct interface between adjacent "layers" and that the "layers" may simply be different regions of the same coating material. The substrate 12 is preferably a transparent, semi-transparent or translucent material, for example, such as plastic, ceramic or, more preferably, glass. For example, the glass can be clear floating glass or it can be clear flat glass tinted or colored. The glass can be of any composition having any optical properties, for example, any visible transmission value, ultraviolet transmission, infrared transmission and / or total solar energy transmission. The types of glass that can be used in the practice of the invention, but not limited thereto, are described in U.S. Patent Nos. 4,746,347; 4,792,536; 5,240,886; 5,385,872 and 5,393,593. The substrate12 may be of any thickness but preferably has a thickness of about 2 mm to about13 mm, preferably from about 2.2 mm to about 6 mm. The coating 14 is preferably a multi-component coating, ie, it contains a plurality of layers or regions of different composition, deposited on at least a portion of the surface of the substrate in any convenient manner, such as but not limited to cathodic vapor deposition. by magnetron (MSVD), chemical vapor deposition (CVD), spray pyrolysis, sol-gel, etc. In the presently preferred practice of the invention, the coating14 is applied by CVD. The CVD coating methods are well understood by those skilled in the film deposition technique and, therefore, will not be explained in detail. In a typical pyrolytic coating process, such as a CVD coating process, gaseous or vaporous precursor materials, or a mixture of such precursor materials, are directed towards the surface of a hot substrate. The precursor materials pyrolyze and nucleate at the surface of the substrate to form a solid coating material, typically an oxide material, whose composition is determined by the type and / or amount of the precursor materials used and the composition of the carrier gas. Still referring to Figure 1, the first region or layer 16 preferably includes a metal oxide material, such as an oxide of one or more of Zn, Fe, Mn, Al, Ce, Sn, Sb, Hf, Zr, Ni , Zn, Bi, Ti, Co, Cr, Si or In or an alloy, such as zinc stannate.
The first layer 16 also preferably includes one or more dopant materials, such as Sn, F, In or Sb. In the presently preferred practice of the invention, the first layer 16 is tin oxide doped with antimony, with the antimony present in the precursor materials in an amount of less than about 10 percent by weight based on the total weight of precursor materials, more preferably less than about 7.5 percent by weight. In a presently preferred embodiment, the first layer 16 preferably has a thickness of about 1000A to about 2300A, more preferably from about 1700A to about 2300A, and most preferably about 2000A. In this presently preferred embodiment, it is preferred that the atomic ratio of tin to antimony (Sn / Sb) in the first deposited layer 16 be from about 8 to about 12, more preferably from about 10 to about 11, as measured by X-ray fluorescence The first layer 16 is preferably applied in such a way that the structure of the first layer 16 is crystalline or substantially crystalline, ie, greater than about 75% crystalline. The first layer of tin oxide doped with antimony 16 promotes the absorption of visible and near infrared solar energy. Although preferred at present, the first layer 16 is not limited to tin oxide doped with antimony. The first layer 16 could also include one or more metal oxides, such as tin oxide, doped with a plurality of dopants, such as antimony and fluorine. Alternatively, the first layer 16 could be a gradient layer, for example, with a mixture of tin oxide doped with fluorine and tin oxide doped with antimony with a continuously changing composition as the distance of the substrate 12 increases. For example, near the surface of the substrate the first layer 16 could be predominantly tin oxide doped with antimony while the external surface or region of the first layer 16 could be predominantly tin oxide doped with fluorine with continuously changing ratio of antimony to fluorine between them. A suitable method of making such a gradient layer is described in U.S. Patent No. 5,356,718, incorporated herein by reference. In addition, the first layer 16 may include two or more layers or regions of metal oxide, for example, of tin oxide, the layers having a different concentration of dopant. A suitable method of forming such strata is also described in U.S. Patent No. 5,356,718. The second layer 20 is preferably a metal oxide layer, preferably a doped metal oxide layer, and may be similar to the first layer 16 described above. Although not to be construed as a limitation, in the presently preferred practice of the invention, the second layer 20 is a layer of tin oxide doped with fluorine, the fluorine being present in the precursor materials in an amount of less than about 20 percent. by weight based on the total weight of the precursor materials, preferably less than about 15 weight percent, and more preferably less than about 13 weight percent. Although not specifically measured, it is estimated that fluorine is present in the deposited second layer 20 in an amount less than about 5 atomic percent. It is believed that if fluorine is present in more than about 5 atomic percent, it can affect the conductivity of the coating that can change the emissivity of the coating. The second layer 20 is also crystalline or substantially crystalline. In a presently preferred embodiment, the second layer 20 preferably has a thickness of about 2000A to about 5000A, more preferably about 3000A to about 3600A. The second layer of tin oxide doped with fluorine 20 promotes low emissivity. According to the invention, the interruption layer 18 is located between the first and second crystalline layers 16 and 20. The interruption layer 18 is a region or layer that prevents, inhibits or reduces the epitaxial growth of crystals of the second substantially crystalline layer. on the first substantially crystalline layer 16, for example, disrupting or interrupting the crystal structure of the coating. Although not to be construed as limitation, in the presently preferred practice of the invention, the interruption layer 18 is preferably an amorphous layer. Thus, when the second layer 20 is formed, the precursor materials of the second layer nucleate in the interruption layer 18 and do not grow epitaxially in the first crystalline layer 16. This prevents or reduces the crystals of the second layer 20 from continuing the structure. -the crystal of the first layer crystals to inhibit the formation of a plurality of unique, substantially continuous, sawtooth-shaped crystals that extend substantially through the coating and thereby reduce the surface roughness that in turn it reduces the turbidity of the coating 14. Although in the presently preferred practice of the invention the interruption layer 18 is preferably amorphous, the interruption layer 18 can also be a non-amorphous layer that promotes the formation of smaller crystals in the second layer 20 which would then be formed in the absence of the interruption layer 18. For example, the interruption layer 18 can be a cap a crystalline, polycrystalline, or substantially crystalline with different lattice parameters with respect to the first layer 16 to obtain a mismatch of the lattice to disturb or interrupt the crystal growth of the coating. The interruption layer 18 should be thick enough to avoid, inhibit, or reduce the epitaxial growth of crystals of the crystals of the second layer in the crystals of the first layer but should not be so thick as to negatively impact the mechanical or optical characteristics of the coating 14. In the presently preferred practice of the invention, the interruption layer 18 is less than about 1000 A thick, more preferably from about 100 A to about 600 A thick. The interruption layer 18 and / or the first layer 16 and / or the second layer 20 may be homogeneous, non-homogenous or of gradual change of the composition. A layer is "homogeneous" when the surface or upper portion, the surface or lower portion, and portions of the layer between the upper and lower surfaces have substantially the same chemical composition as they pass from the lower surface to the upper surface and vice versa . A layer is "graded" when the layer has a substantially increasing fraction of one or more components and a substantially decreasing fraction of one or more different components as it passes from the upper surface to the lower surface or vice versa. A layer is "inhomogeneous" when the layer is different from homogeneous or graduated. In a currently preferred practice of the invention, the interruption layer 18 is a phosphorus-containing metal oxide layer, for example, a tin oxide layer, the phosphorus being present in the mixture of deposition precursor materials in an amount less than about 20 percent by weight, preferably less than about 10 percent by weight, and more preferably about 3 percent by weight based on the total weight of the mixture of precursor materials. It is believed that the phosphorus and the tin oxide precursor materials form a mixed oxide or solid solution when deposited on the first layer 16, ie, the phosphorus and the tin oxide are together in solid form without losing their chemical identity. Although not specifically measured, it is estimated that the atomic ratio of phosphorus to tin (P / Sn) in a presently preferred embodiment of a deposited interruption layer 18 is from about 0.01 to about 0.10, more likely from about 0.03 to about 0.08, and most likely from about 0.04 to about 0.06. In the preferred practice of the invention, the interruption layer 18 is preferably not an alloy because it is preferably non-crystalline. In an alternative embodiment, the interruption layer 18 can be a mixed oxide of tin and silica, for example, a solution of solid tin and silicon oxide. In a currently preferred practice, the silica precursor material includes less than about 20 weight percent of the combined silica and tin precursor materials based on the total weight of the combined silica and tin precursor materials. In a presently preferred embodiment of the invention, the atomic ratio of silicon to tin (Si / Sn) in the deposited interruption layer 18 is estimated to be from about 0.005 to about 0.050, more likely from about 0.010 to about 0.035, and most likely from about 0.015 to about 0.025. The interruption layer 18 could also be a mixture of materials that inhibit or disturb the growth of crystals, such as a metal oxide with phosphorus and silica. The protective layer 22 is preferably a 2T materialchemically resistant dielectric that has desirable optical properties, manageable deposition characteristics and is compatible with the other materials of the coating stack. Examples of suitable protective materials include titanium dioxide (U.S. Patent Nos. 4,716,086 and 4,786,563), silicon dioxide (Canadian Patent Number 2,156,571), aluminum oxide and silicon nitride (U.S. Pat. 5,425,861; 5,344,718; 5,376,455; 5,584,902; 5,834,103; and 5,532,180 and PCT Publication No. WO 95/29883), silicon oxynitride, or silicon aluminum oxynitride (Patent Application Ser. United States No. 09 / 058,440), the descriptions of which are incorporated herein by reference. In the presently preferred practice of the invention, the coating 14 is applied by CVD. For example, a conventional CVD coating or "coater" device having a plurality of coater grooves may be spaced from a glass ribbon supported on a molten metal bath contained in a chamber having a non-oxidizing atmosphere, for example. example, of the type described in U.S. Patent No. 4,853,257, which is incorporated herein by reference. CVD coating techniques are known to those of ordinary skill in the art of thin film deposition and therefore will not be explained in detail. Examples of CVD coating apparatuses and methods are found, for example, but are not to be construed as limiting the invention, in U.S. Pat. Nos. 3,652,246; 4,351,861; 4,719,126; 4,853,257; 5,356,718; and 5,776,236, which are incorporated herein by reference. An exemplary method of forming a coating of the invention will now be described, for example, a tin oxide coating coated with antimony / interruption layer / tin oxide doped with fluorine. To deposit a first layer 16 of tin oxide doped with antimony, a tin oxide precursor, such as monobutyltin chloride (MBTC), is mixed with an antimony precursor, such as SbCl 3 or SbCl 5, and the precursors are applied over the substrate through one or more coater grooves when the substrate moves under the coater. In the practice of the invention, the antimony precursor, such as SbCl 5, is present in a quantity of less than about 20 weight percent of the total weight of the combined MBTC and SbCl 5 material. The material of the first layer is applied to form a first layer 16 preferably from about 1000A to about 2300A thick, more preferably from about 1700A to about 2300A. Next, MBTC mixed with an interruption layer material is deposited on the material of the first layer through one or more other coater grooves downstream of the first coater groove (s). Preferably, the interrupter material is triethylphosphite (TEP) to obtain an interruption layer of tin oxide containing phosphorus 18. The PET is preferably less than about 20 weight percent based on the total weight of the combined MBTC and TEP material, more preferably less than about 10 weight percent, and most preferably about 3 weight percent. The resulting phosphorus containing disruption layer 18 preferably has less than about 600 A thick. Phosphorus can adversely affect the optical properties of coating 14, such as iridescence. Therefore, the thickness of the phosphorus-containing interrupting layer 18 should be selected to avoid the epitaxial growth of a second metal oxide layer following but not so thick that it negatively impacts the optical properties of the coating 14. Alternatively, the interruption can be tetraethylorthosilicate (TEOS) to obtain an interruption layer containing silica and tin oxide 18. In this alternative embodiment, the TEOS is preferably less than about 20 weight percent based on the total weight of the combined MBTC and TEOS precursors. The rest of the deposition capabilities of the re-coater can be used to apply a mixture of MBTC and a fluorine precursor, such as trifluoroacetic acid (TFA), on the substrate to form the second layer of tin oxide doped with fluorine 20 over the interruption layer 18. The TFA preferably includes less than about 20 weight percent of the total weight of the MBTC and TFA material, more preferably less than about 15 weight percent. The interruption layer 18 of the present invention is not limited to use with the coating 14 described above. Rather, the "interruption layer" concept of the invention can be applied to other coating stacks that provide desirable solar control properties but which may have so far been limited in commercial use due to unacceptably high turbidity. For example, as explained above, tin oxide material doped with fluorine has been used to form low emissivity coatings. However, at thicknesses greater than about 2000A, a conventional crystalline coating of tin oxide with fluorine exhibits commercially undesirable haze, for example, greater than about 2%. As shown in Figure 2, the present invention can be used to mitigate this problem by interposing one or more interrupter layers 18 of the present invention in a conventional replenishment of fluorinated dope tin oxide to break the oxide coating tin doped with fluorine in a plurality of fluorine-doped tin oxide layers, regions or layers 30 separated by interruption layers 18. Each crystalline layer of fluoride-doped tin oxide is preferably less than about 4000 A thick, more preferably less than about 3000A thick, more preferably less than about 2000A thick, and most preferably less than about 1000A thick. Thus, the interruption layers 18 prevent the formation of large tin oxide crystals doped with fluorine, ie, greater than about 2000 A thick, and therefore reduce the resulting turbidity of the coating. Multiple coatings of other known coating materials can be formed, such as, but not limited to, one or more doped or undoped crystalline metal oxides, similarly to reduce the formation of turbidity in the overall coating by incorporating a several layers of interruption 18 to the coating stack to break the coating into a plurality of crystalline coating regions, each coating region having a thickness of less than about 4000 A, preferably less than about 3000 A, more preferably less than about 2000A, and most preferably less than about 1000A. In the preferred embodiments discussed above, the interruption layer 18 of the invention is located between selected crystalline layers of the coating stack. However, the interruption layer 18 could also be used as a "topcoat", that is, a layer deposited on top of the outer crystalline layer of the stack of functional coatings to smooth the rough outer surface of the underlying crystalline layer. , similarly as described in U.S. Patent No. 5,744,215, which is incorporated herein by reference. For example, one or more crystalline coating layers could be deposited on the substrate, with or without the interposition of one or more interruption layers 18 as described above, to form a stack of functional coatings. After depositing the crystalline layers, an interruption layer 18 of the invention could then be deposited on the outer surface of the outer crystalline layer to smooth the outer crystalline surface, that is, to fill and / or smooth the channels or valleys on the rough outer crystalline surface to reduce surface turbidity. This "top coating" of the interruption layer could optionally be covered with a temporary or permanent protective layer 22. When used as a topcoat, it is believed that the interruption layer 18 could be thicker than when used as an intermediate layer. As explained above, in addition to the problem of turbidity, many solar control coatings also exhibit commercially undesirable iridescence. The present invention also provides coatings, in particular low emissivity coatings, with improved iridescence properties. For example, Figure 3 shows a low emissivity coating 40 of the present invention having reduced iridescence. The coating 40 includes a color suppression layer 42 deposited on the substratum 12 with a first functional region or layer 44, for example, a doped metal oxide layer, deposited on the color suppression layer 42. The Color suppression 42 is preferably a gradient layer that passes from one metal oxide or nitride to another. Examples of suitable layers of color suppression 42 are described, for example, in U.S. Patent Nos. 4,187,336; 4,419,386; 4,206,252; 5,356,718; No. 5,811,191, which are incorporated herein by reference. For example, the color suppression layer 42 may be a gradient layer including a mixture of silicon oxide and a metal oxide, such as tin oxide with a continuously changing composition as the distance of the substrate 12 increases. For example, near or adjacent the surface of the substrate 12, the color superset layer 42 may be predominantly silicon oxide while the outer surface or region of the color suppression layer 42 may be predominantly tin oxide. The color suppression layer 42 preferably has a thickness of about 50 Á to about 3000 Á, preferably about 1000 Á. The color suppression layer 42 is preferably amorphous and can be deposited by any known deposition technique. For example, for floating glass systems, conventional chemical vapor deposition techniques (CVDJ) are preferred, however, the color suppression layer 42 can also be deposited by other known techniques, such as spray or deposition pyrolysis. magnetron vacuum (MSVD), in addition, although a graduated layer of color suppression 42 is preferred, the color suppression layer42 can also be a single component layer or multiple component layer, as is known in the art.
The first layer 44 is preferably composed of a transparent conductive metal oxide, such as antimony doped tin oxide, the antimony being present in an amount of about 10 weight percent to about 30 weight percent, preferably about 15 weight percent to about 20 weight percent, based on the total weight of the first layer 44 or the precursor materials. The first layer 44 preferably has a thickness of about 700A to about 3000A. However, if the thickness of the first layer 44 is greater than about 1500A to about 2000A, one or more interruption layers 18 of the invention may be used to divide the first layer 44 into a plurality of regions or sublayers as shown in FIG. described above to reduce haze, each sublayer having less than about 2000 A thick, preferably less than about 1500 A, and more preferably less than about 1000 A and being separated from an adjacent sublayer by an interruption layer 18. Optionally, a second layer 46 can be deposited on the first layer 44. As the dashed lines in Figure 3 show, an optional interruption layer 18 of the invention can be placed between the first and second layers 44 and 46. The second layer 46 is preferably a doped metal oxide material, such as tin oxide doped with fluorine and / or indium or, alternatively, indium oxide doped with year. In a currently preferred practice, the second layer 46 is fluorine-doped tin oxide with the fluorine present in an amount of about 10 weight percent to about 30 weight percent based on the total weight of the second layer 46 or the precursor materials. The second layer 46 has a thickness from about 0 Á to about 3000 Á, the thickness of the second layer 46 preferably being inversely proportional to the thickness of the first layer 44, ie, when the first layer of tin oxide doped with antimony 44 is at or near its upper preferred limit (3000 Á), the second fluorinated dope tin oxide layer 46 is at or near its preferred lower limit (approximately 0 Á), ie, the second layer 46 may not be present ( 0 Á) or, if present, it is very fine (> 0 Á). On the other hand, when the first layer of tin oxide doped with antimony 44 is at or near its preferred lower limit (700 Á), the second layer of tin oxide doped with fluorine is preferably at or near its limit. preferred top (3000 Á). However, as explained above, when the desired thickness of the second layer 46 is greater than about 1500 A to about 2000 A, one or more interruption layers 18 of the invention can be used to divide the second layer 46. in a plurality of sublayers to reduce the turbidity of the coating, each sublayer having less than about 1500 Á to about 2,000 Á of thickness. Thus, as can be appreciated by those skilled in the art, the present invention provides a low emissivity coated glass substrate, for example, having an emissivity of less than about 0.2, which also has a low shade coefficient, example, less than about 0.5, preferably about 0.44, and low turbidity, for example, less than about 1.5%, using one or more interruption layers 18 of the invention. The present invention also provides a low emissivity solar control coating with reduced iridescence using a color suppression layer 42 in conjunction with one or more layers of doped metal oxide. The problems of both turbidity and iridescence can be solved simultaneously by providing a coating with one or more interruption layers and a color suppression layer. The present invention further provides a coated substrate which may have a first functional layer and a second functional layer, with an interruption layer18 of the invention located between the two functional layers. As will be understood from the above explanation, the first functional layer could include a solar control coating layer, such as tin oxide doped with antimony, or a color suppression layer. The second functional layer could include a low emissivity coating layer, such as tin oxide doped with fluorine. Alternatively, the first and second functional layers could be solar control layers or both could be low emissivity coating layers. Those skilled in the art will readily appreciate that modifications can be made to the invention without departing from the ideas described in the foregoing description. Accordingly, the particular embodiments described in detail herein are illustrative only and will not limit the scope of the invention, to which the full scope of the appended claims and any and all equivalents thereof must be given. EXAMPLE I This example illustrates the use of an interruption layer containing phosphorus of the invention. In this example, five basic precursor components were used, each of which can be purchased on the market from ELF Atochem, NA The five components were monobutyltin chloride (MBTC, commercial name ICD-1087), tetraethylorthosilicate (TEOS), triethylphosphite (TEP), trifluoroacetic acid (TFA), and a mixture of 20 weight percent antimony trichloride in MBTC (ATC, vendor code ICD-1133). In this example, the ATC was diluted with MBTC to obtain a concentration of 7% by weight of antimony trichloride in MBTC. This mixture was fed to a conventional fill tower evaporator and heated to 176.6 ° C (350 ° F) to vaporize the mixture. Nitrogen was used as a carrier gas and was fed countercurrently through the evaporator to form a mixture # 29nitrogen gas, MBTC and antimony trichloride. This gaseous mixture was further diluted with air at 0.8 to 1.0 mole percent reactive species. This gaseous mixture was fed to a coating station of the type disclosed in U.S. Patent No. 4,853,257, incorporated herein by reference. The mixture of precursors was directed through the coating station and onto a 3.3 mm piece of clear floating glass having a temperature of about 648.8 ° C (1200 ° F) at about 660 ° C (1220 ° C). F) and moving at a speed of 1,016 cm / minute (400 inches / minute) to 1,828 cm / minute (720 inches / minute) below the coating station. When the mixture of precursors contacted the glass, the thermal energy of the glass pyrolyzed the precursor components to form a region or layer of crystalline coating of tin oxide doped with antimony in the glass. The gaseous products of the reaction and the unused chemical vapor were expelled to a conventional thermal oxidizer followed by a filter chamber. In the next coating station, MBTC and TEP were separately evaporated as described above in the presence of nitrogen carrier gas and the two gaseous precursor materials were combined to obtain a mixture of 3 weight percent of TEP in MBTC. This mixture was diluted with air at 0.8 to 1.0 mole percent reactive steam and directed through a second coating station of the same type as described above on the previously coated glass substrate. When the mixture contacted the coated surface, the TEP and MBTC pyrolyzed to form an amorphous layer or tin oxide region mixed with phosphor over the first coating region. In the next coating station, TFA was mixed as a liquid to a 3T feed streamMBTC liquid to obtain a mixture of 12 weight percent TFA in MBTC. This mixture was evaporated as described above in the presence of nitrogen carrier gas and further diluted with air to 0, 8 to 1.0 mole percent reactive steam. This steam was then directed over the previously coated substrate to the third coating station to form a coating region or layer of tin oxide doped with fluorine on the interruption layer. The final product was a three-layer pile over 3.3 mm of clear floating glass. It is estimated that the stack had a first layer of tin oxide doped with antimony of about 1750A, a stop layer of tin oxide containing phosphorus of about 450A at about 650A, and a second layer of tin oxide. doped with fluorine of about 3400 Á. The coated substrate had a shadow coefficient of 0.44 for a single sheet, a visible light transmittance of 48%, an emissivity of 0.18 and a turbidity of 0.8 percent. The reflected color was a pale green to blue-green and the color transmitted was neutral gray to blue-gray. It is expected that without the interruption layer 18 the coated substrate would have a turbidity greater than about 3 percent. EXAMPLE II This example illustrates the use of an interruption layer containing silicon of the invention. Another coated substrate was prepared in a manner similar to that set forth in Example I, but a mixture of TEOS and MBTC was applied in the second coating station to form an interruption layer of tin oxide and silica. The TEOS and MBTC were mixed to obtain a mixture of 1.2 to 1.4 weight percent (0.5 to 0.8 mole percent) TEOS in MBTC, which was further diluted with air at 0.8 to 1 , 0 mol percent reactive vapor.
It is estimated that the clear floating glass of 3.3 nm coated had a first layer of tin oxide doped with antimony of 1750 Á, an interruption layer of tin oxide and silica of about 450 Á at 650 Á, and a layer of Tin oxide doped with fluorine of 3400 Á. This coated substrate had a shadow coefficient of 0.44 for a single sheet, a visible light transmittance of 48%, an emissivity of 0.18 and a turbidity of 1.5%. EXAMPLE III Considering next the iridescence problem, Figure 4 shows the solar absorption of several tin oxide coatings doped with antimony deposited on clear floating glass by CVD. The parameters of the CVD process that produced these coatings are listed in Table 1. Other known deposition processes such as pyrolytic coating techniques and cathodic deposition coating techniques, such as MSVD, can be naturally used. Table 1 MuesTemp. Conc. Conc. Relac flow Thickness Vel. tra n ° glass MBTC gas water exhaust glass line° F mol% mol% SLM1% gas mm p / min1 1000 0.5 0.5 55 115 4 502 1200 0.5 0.5 55 115 4 504 1200 0.5 0 55 115 4 506 1200 0.1 0.5 55 115 4 508 1200 0.1 0 55 115 4 509 1000 0.5 1 55 115 4 501000 1 0,5 55 115 4 5011 1000 1 1 55 115 4 50Standard liters / minuteThe spray coating was performed using a mixture of 5 weight percent of an antimony precursor, such as antimony trichloride, in a metal oxide precursor, such as monobutyltin trichloride (MBTC), and pulverized by hand on a clear glass substrate heated to approximately 621 ° C (1150 ° F). the antimony precursor was fed at 20% by constant weight relative to the MBTC. The coater had a central inlet slot with exhaust slots up and down. The width of the coating zone was 10.16 cm (4 inches) and the contact length between leaks was 12.7 cm (5 inches). Air was used as the carrier gas. The metal oxide precursor decomposes on the surface of the glass substrate to form tin oxide, with the antimony dopant supplied by the decomposition of the antimony precursor. As shown in Figure 4, coatings 4 (S4) and 8 (S8) absorb more NIR energy than visible light, making the coatings good for solar control when high visible light transmission is needed. Coatings 2 (S2) and 6 (S6) have maximum absorption at about 550 nm. These coatings are suitable for quenching the green color of some conventional glass, such as Solex® glass and Solargreen® glass marketed from PPG Industries, Inc., of Pittsburgh, Penn-sylvania. The coating 10 (S10) absorbs more visible light than NIR light, the coating 1 (SI) absorbs a relatively constant amount through the solar spectrum and the coatings 9 (S9) and 11 (Sil) absorb appreciable UV light. A significant issue for coatings that will be glazed in the annealed and tempered states is the permanence of the color, or color that does not change when the coated glass is heated. The appearance and performance should be the same before and after the heat treatment. The tin oxide coatings doped with antimony of the invention may or may not change upon heating, depending on the deposition parameters. Table 2 lists the properties of several samples and how some properties change with heat treatment. The units of thickness are Á. The sample numbers with an H after them indicate the samples after the heat treatment. The samples were exposed to 649 ° C (1200 ° F) for approximately four minutes and then cooled to room temperature. Table 2 Conc. Port. Res. Mov. Super hall. Hall NMR H- Hall Abs. no NNR H- 50 NMR H- pond. IR cer¬Thickness 50 (* E20 50 UV-Vis medium (cm2 / port / (ohm / 300-700 700- .stra.stra.v.) cm3) 1 quad) nm 2500 nm1 665 7,52 2,35 3, E + 05 0,159 0,1912 795 0.72 1.49 7, E + 03 0.307 0.2984 310 0.54 4.57 9, E + 03 0.173 0.2568 153 0.54 4.95 2, E + 04 0.142 0.211675 6.70 6.03 2, E + 06 0.203 0.21411 879 4.90 9.48 6, E + 05 0.254 0.2241 H 1.02 1.07 3, E + 05 2 H 0.47 2.23 8, E + 03 4 H 0.42 4.89 L, E + 04 8 H 0.35 4, 84 2, E + 04 10 H 0 , 04 3.41 2, E + 05 11H 8.35 1.92 2, E + 05 MuesTx Ty R1Y Rlx Rly R2Y R2x R2y tra 1 67.7 0.312 0.319 21.0 0.299 0.307 17.6 0.294 0.303 2 50, 2 0,295 0,298 21,8 0,333 0,337 16,3 0,324 0,327 4 76,5 0,306 0,316 12,2 0,294 0,297 9,2 0,280 0,284 8 85,0 0,307 0,317 9,2 0,301 0,308,0,095 0,30276.0 0.313 0.321 16.0 0.294 0.302 13.4 0.295 0.305 11 67.9 0.309 0.316 21.3 0.318 0.330 17.6 0.318 0.333 1H 70.1 0.312 0.320 19.2 0.298 0.306 16.6 0.293 0.303 2H 52 , 5 0.296 0.301 21.5 0.326 0.330 16.0 0.315 0.318 4H 76.7 0.306 0.316 12.2 0.294 0.299 9.2 0.280 0.288 8H 85.1 0.307 0.317 9.2 0.301 0.308 8.0 0.295 0.302 10H 72.1 0.312 0.320 18.3 0.295 0.304 16.1 0.291 0.302 11H 69.3 0.309 0.317 20.5 0.313 0.325 18.1 0.309 0.326DE DE DE Sample Delta T Delta Delta Macadam Macadam Macadam Rl R2 T Rl R21 2.38 -1.78 -0.96 3.21 4.98 3.32 2 2.25 -0.32 -0.3 3.79 5.16 6.56 4. 0.14 -0.02 0.01 0.26 0.1 0.19 8 O, 12.0.07 -O, 02 0.18 0.31 0.15-. 10 -3,9 2,32 2,68 4,74 7,38 9,96 11 1,34 -0,81 0,49 1,9 4,48 6, 941 Exponent (E) multiplied by electron carrier1020 / cm3 Rl is the reflectance of the coated side while R2 is the reflectance of the non-coated side of glass and T is the luminant transmission. Also DE is the color change. The optical constants for the sample 8 before the heat treatment are set forth in Table 3 below. These optical constants are also those used in the other following examples.
Table 3 Wavelength index refractive index imaginary realization350, 0 1,89450 0,09050 360,0 1,88140 0,07227 370,0 1,86920 0,05884 380, 0 1, 85800 0,04934 390,0 1,84750 0, 04301 400,0 1, 83770 0.03929 410.0 1.82850 0.03770 420.0 1.81990 0. 03783 430.0 1.81180 0.03938 440.0 1.80420 0.04209 450.0 1.779700 0.04573 460 , 0 1,79020 0, 05013 470,0 1,78370 0,05514 480,0 1,77760 0, 06065 490,0 1,77170 0,06655 500,0 1,76610 0,07276 510,0 1,76070 0,07922 520,0 1,75550 0,08586 530,0 1,75060 0,09265 540,0 1,74580 0,09954 550,0 1,74120 0,10650 560, 0 1,73670 0,11351 570, 0 1,73240 0, 12054 580.0 1,72820 0.12759 590, 0 1,72420 0,13463 600,0 1,72020 0,14165 610,0 1,71630 0,14865 620,0 1,71250 0 , 15563 630.0 1.70880 0.16256 640.0 1.70520 0.166947 650.0 1.70160 0.177633 660.0 1 69810 0.188315 * 670.0 1.69470 0.18993 680.0 1,69120 0,19667 690,0 1,68790 0.20337 700, 0 1,68460 0,21003 710,0 1,68130 0,21665 720,0 1,67800 0,22323 730,0 1,67480 0, 22979 740.0 1.67150 0.23631 750.0 1.66830 0.244280 760.0 1.66520 0.244926 770.0 1.66200 0.2570 780.0 1,65880 0,26212 790,0 1,65570 0,26852 800,0 1,65260 0,27491 810,0 1,64940 0,28128 820,0 1,64630 0,28764 830, 0 1,64310 0, 29399 840.0 1.64000 0.30033 850.0 1.63680 0.30668 860.0 1.63370 0.31302 870.0 1.63050 0.31936 880.0 1.62730 0.32571 890, 0 1 , 62410 0.33206 900.0 1.62090 0.33842 910.0 1.61770 0.344480 920.0 1.61450 0.35118 930, 1.61120 0.35759 940.0 1.60790 0.36401 950.0 1,60460 0,37045 960.0 1,60130 0,37691 970.0 1,59800 0,38339 980,0 1,59460 0,38990 990,0 1,59120 0,39644 1,000,0 1, 58780 0.40301 1010.0 1.58440 0.40961 3?1020.0 1.58090 0.41624 1030.0 1.57740 0.42290 1040.0 1.57390 0.42960 1050.0 1.57040 0.43634 1060.0 1.56680 0.44311 1070.0 1, 56320 0.44993 1080.0 1.55950 0.455679 1090.0 1.55580 0.46369 1100.0 1.55210 0.47064 1110.0 1.54840 0.47763 1120.0 1.54460 0.48467 1130 , 0 1.54080 0.49175 1140.0 1.53700 0.49889 1150.0 1.53310 0.50608 1160.0 1.52920 0.51332 1170.0 1.52520 0.52061 1180.0 1.52120 0,52796 1190, 0 1,51720 0,53536 1,200,0 1,51310 0,54282 1210,0 1,50900 0,55033 1220,0 1,50480 0,55791 1230,0 1,50070 0,56554 1240, 0 1,49640 0.57324 1250.0 1.49220 0.58099 1260.0 1.48790 0.58881 1270.0 1.48350 0.59669 1280.0 1.47910 0.60463 1290.0 1.47470 0 , 61264 1300.0 1.47020 0.62072 1310.0 1.46570 0.62886 1320.0 1.46110 0.63707 1330.0 1.45650 0.64534 1340.0 1.45180 0.65369 1350.0 1,44710 0.66210 1360.0 1.44240 0.67058 1370.0 1.43760 0.679141380.0 1.43280 0.687771390.0 1.42790 0.696471400.0 1.42300 0.705241410.0 1.41800 0.714081420.0 1.41300 0.723001430.0 1.40790 0.732001440.0 1,40280 0.741071450.0 1.39760 0.750221460.0 1.39240 0.7559441470.0 1.38720 0.768741480.0 1.38190 0.778121490.0 1.37650 0.787581500.0 1.37110 0.7997121510.0 1.36560 0.806741520.0 1.36010 0.816431530.0 1.355460 0.826211540.0 1.344900 0.836071550.0 Í, 34330 0.846011560.0 1.33760 0.856041570.0 1.33190 0.866141580.0 1.32610 0, 876331590.0 1.32020 0.886611600.0 1.31430 0.896971610.0 1.30830 0, 907411620.0 1.30230 0.917941630.0 1.29630 0.928551640.0 1.29020 0.939261650.0 1.2884 0.950041660.0 1.27780 0.960921670.0 1.27150 0.971881680.0 1.26520 0.982931690.0 1.25880 0, 994071700.0 1.25230 1.005301710.0 1.24580 1, 01660 1720.0 1.23930 1.02800 1730.0 1.23270 1.03950 1740.0 1.22600 1.05110 1750.0 1.21930 1.06280 1760.0 1, 21260 1.07460 1770.0 1.20580 1.08640 1780.0 1.9890 1.09840 1790.0 1.19190 1.11040 1800.0 1.1885 1.126060 1810.0 1.177790 1.3480 1820 , 0 1,17080 1,14720 1830,0 1,16370 1,15960 1840,0 1,15650 1,17210 1850,0 1,14920 1,18470 1860,0 1,14190 1,19740 1870,0 1,13450 1,21020 1880,0 1,12700 1,22310 1890,0 1,11950 1,23610 The application of a coating that selectively absorbs or preferably NIR sunlight as opposed to visible light would be useful when making a good solar control battery. It is predicted that a single layer of tin oxide doped with antimony, with the optical properties listed above, having 800 A in thickness, has approximately a visible transmission of 69% and approximately 58% TSET. The antimony doped tin oxide layer of the invention preferably has from about 700A to about 3000A thick. Tin oxide doped with antimony absorbs light through the entire solar spectrum. It also has a very high absorption of green light. Thus, by placing a coating containing tin oxide doped with antimony on a green glass substrate, the transmitted color can be changed from green to gray, creating a high performance solar control glass with neutral aesthetics.4TThe theoretical coatings described below were molded using a software program marketed "TFCalc", as described in more detail below. Predictive Example IV A tin oxide layer doped with antimony can be combined with an additional doped metal oxide layer, such as a fluoride doped tin oxide layer, a tin oxide layer doped with indium or a mixture of oxides of tin doped with indium and fluorine to achieve both low emissivity and a reduction in transmission. Tin oxide doped with fluorine and / or indium has a higher refractive index than tin oxide doped with antimony. Tin oxide doped with fluorine is electrically conductive and has a high refractive index in the UV and visible parts of the spectrum and low refractive index in the NIR. For purposes of explanation, the term "high refractive index" generally means a refractive index greater than about 1.9 and "low refractive index" means a refractive index less than about 1.6. "Mean refractive index" refers to a refractive index between about 1.6 and 1.9. In the invention, the fluorine-doped tin oxide coating has between about 0 Á to about 3,000 Á of thickness, preferably the thickness of the fluoride-doped tin oxide layer is inversely related to the thickness of the oxide layer of tin doped with antimony. When the tin oxide layer coated with antimony is close to its upper preferred limit, ie about 3,000 A, the fluorine-doped tin oxide layer is preferably at or near its preferred lower limit, i.e., about 0 Á. The other wayWhen the tin oxide doped with antimony is close to its preferred lower limit, ie 700 Á, the tin oxide doped with fluorine is preferably close to its upper preferred limit, ie 3000 Á. FIG. 5 shows the theoretical light transmission of a graduated layer antimony-doped tin oxide coating with fluorine and tin oxide. The total (TSET) is approximately 51% and the visible light transmission is approximately 69%. TSET and visible light transmission can be altered with this design by varying the thickness of the tin oxide layer doped with antimony or by changing the antimony concentration in the coating. As a general rule, when the thickness of the tin oxide layer doped with antimony increases or when the concentration of antimony increases, the TSET and the transmission of visible light decrease. Government regulations impose window performance. A new final performance for the southern United States of America is that the windows have a shadow coefficient of approximately 0.45. This can be achieved with a TSET of approximately 37%. The coating described for Figure 5 can be altered to reach said final value by increasing the thickness of the tin oxide layer doped with antimony. The transmission curve for this coating is shown in FIG. 6. This coating has a visible light transmission of approximately 52% and a TSET of approximately 37%. The fluorine-doped tin oxide coating as the top layer will give this coating an emissivity of less than about 0.35. The thickness of the graduated layer is 800A, the tin oxide doped with antimony is 1800A and the tin oxide doped with fluorine is 1800A in this example. The TSET of this coating can be further reduced by the application of a high quarter wave index layer, such as Ti02, on top of the graduated tin oxide doped with antimony and fluorinated dope tin oxide discussed above. . The TSET falls to 32.5% but the visible transmission only falls to 51%. The transmission curve of these cells, with and without the Ti02 layer, is represented in figure 7. Theoretical coatings were modeled using the commercialized software program TFCalc. The solar heat transmittance was calculated using an integrated air mass of 1.5 defined in ASTM E 891-87. Visible transmittance was calculated from the output of TFCalc using Illuminant C. The color suppression layer was close to a layer made of 20 sheets with small changes in the refractive index. The number of sheets was varied to obtain a specific refractive index in the upper part of the graduated index layer. The refractive indices of the sheets varied from 1.5 to 2.0 in increments of 0.05. This approach for the graduated index layer was made because the software does not have the ability to model a coating with a continually changing refractive index. Such an approach method is known in the art of modeling coatings. The optical constants described below of the graduated layer are constants as a function of the wavelength on the solar spectrum. This example is for a coating designed for a wavelength of 1230 nm. The graduated layer has a refractive index of 2.0 at the top and the sheets are 10 nm thick. To vary the doped metal oxide layers, the refractive index is important. Tin oxide layer doped with fluorine with a refractive index of 1.42 at the design wavelength was modeled. The incident medium is air with a refractive index of 1.0. Tin oxide layer doped with antimony was modeled with a refractive index of 1.680 at the design wavelength. The physical thickness of the tin oxide layer doped with fluorine would be 2166 angstroms and the tin oxide layer doped with antimony 3664 angstroms. This patterned coating theoretically reduces re-flectance over the wavelength range from 1045 nm to 1500 nm compared to a non-coated substrate. The visible transmission is 40, 01%, the solar heat transmission is 27.2 and the difference between the two is 12.80%. The difference in the refractive indices between the doped tin oxide with fluorine and the tin oxide layers doped with antimony is 0.174 at 500 nm, the center of the visible spectrum, and the difference between the refractive indices is 0.260 to 1230 nm , the wavelength designed in the near IR. This coating also has a neutral reflected color. Predictive Example V A modeling similar to that of Predictive Example IV was performed for a coating for a wavelength of 550 nm. The color suppression layer was modeled with a refractive index of 2.0 at the top with sheets 10 nm thick. The tin oxide layer doped with fluorine had a refractive index at the design wavelength of 2.0. The incident medium had a refractive index of 2.0. The antimony doped tin oxide layer had a refractive index of 1.826 at the designed wavelength. The physical thickness of the fluorinated dope tin oxide layer is 702 Á and the antimony doped tin oxide layer is 1539 Á. This coating reduces the reflectance in the wavelength band from about 300 nm to about 1160 nm compared to the uncoated substrate. This coated article is designed for an incident medium of 2.0, but could be used in an incident medium with a different refractive index, such as air with a refractive index of 1.0. For air, the relevant calculated values would be: visible transmission 62.28, solar heat transmission 49.54, with a difference between the two of 12.75%. The difference in the refractive indices between the doped tin oxide with fluorine and the tin oxide layers doped with antimony is 0.174 at 500 nm, the center of the visible spectrum, and the difference between the refractive indices is 0.260 to 1230 nm , a wavelength in the near IR. The coating has a neutral reflected color. Predictive Example VI In the embodiment described above, a color suppression layer was used to avoid the iridescence of the coated article. However, in another embodiment of the invention, no color suppression layer is required. It has been discovered that a novel combination of tin oxide doped with antimony and tin oxide doped with fluorine produces a coated article having a neutral reflected color and low emissivity. In this embodiment of the invention, a substrate, such as glass, has a layer of tin oxide doped with antimony deposited thereon, for example as described above. The tin oxide layer doped with antimony preferably has from about 900A to about 1500A thick, more preferably about 1200A thick. A layer of tin oxide doped with fluorine is then deposited on the antimony doped tin oxide layer in a conventional manner. The fluorinated dope tin oxide layer preferably has a thickness of about 2300 A to about 3600 A, providing a transparent conducting oxide having little or no transmitted color. However, the thickness of the fluorinated dope tin oxide layer can be varied such that the color of the resulting article is varied but remains "hard". Resistant is used here to mean that the color is substantially insensitive to changes in film thickness. The tin oxide layer doped with antimony is preferably from about 900A to about 1500A thick, more preferably about 1200A thick. Tin oxide doped with antimony may have a single concentration of antimony oxide or may be segmented into two or more layers or layers of different concentrations of antimony. One way to make such strata is described in U.S. Patent No. 5,356,718 discussed above. Nevertheless, any known method can be used to make a layer with more than one concentration of a selected material. The presence of multiple layers of different concentrations of antimony oxide and / or the appropriate thickness of tin oxide doped with antimony creates a situation where points of inflection develop in the color of the resulting multiple layer. Figure 8 shows how the color of the multiple layer varies with changes in the thickness of the tin oxide layer doped with fluorine. The circles of color around the neutral, whose center is defined as X = 0.333 and Y = 0.333. The inner spiral is the transmitted color and the outer spiral is the reflected color. There are no points along the spiral of reflected color in which the color changes abruptly, all changes are gradual. The theoretical parameters for Figure 8 are shown to the right of the graph. These parameters are: color standard 1931 CIÉ; Field of view 5.08 cm (2 inches); po-larization: medium; Reference white: CIE-C; Illuminant: white; Incident angle: 0.00 °; the X coordinate is 0,338 for reflection and 0,321 for transmission; the coordinated Y is 0,371 for reflection and 0,323 for transmission; the brightness is 14.24 for reflection and 60.18 for transmission; the dominant (nm) is 569 for reflection and 585 for transmission; the complementary (nm) is 450 for reflection and 484 for transmission; and the purity of excitation is 0.223 for reflection and 0.047 for transmission. The color coils of Figures 8-10 were generated using the TFCalc software. Preferred coatings are those that have abrupt turning points near the neutral point. Now a further embodiment of the invention will be described. Figure 9 shows the color coils for this additional embodiment of the invention having two strands of tin oxide doped with antimony. The first stratum has 985 Á of thickness and the second stratum has 214 Á of thickness. The tin oxide layer doped with fluorine is in the order of from about 1200 Á to about 3600 Á. There are pronounced inflection points at X = 0.3, Y = 0.34 and X = 0.34, Y = 0.32. These two points represent sturdy points. The second point is a little more neutral than the first. The color sensitivity of the overall design can be calculated around the neutral point. Figure 10 shows how the color varies for a variation of the thickness of each layer of 75 Á. The color standard, field of view, polarization, reference target, illuminant and incident angle are the same for Figures 9 and 10 as for Figure 8. However, the remaining parameters were changed as follows (for the parameters Next, the first number is for reflection and the number in parentheses is for transmission). For Figure 6, the X coordinate was 0.305 (0.325); the coordinated Y 0.342 (0.325); luminosity 11.06 (57.92); Dominant 539 nm (584 nm); complementary N / A(483 nm) and excitation purity 0.057 (0.065). For figure 7, the coordinate X 0.333 (0.322); the coordinated Y0.326 (0.328); luminosity 10.55 (56. 63); Dominant 589 nm (578 nm); complementary 486 nm (478 nm); and 0.086 (0.064) excitation purity.