Disclosure of Invention
In order to further improve the polishing removal rate and the slurry stability of lithium tantalate and lithium niobate, the invention provides a polishing composition and a polishing method of lithium tantalate or lithium niobate, aiming at the problems in the prior art.
In a first aspect, the present invention provides a polishing composition of lithium tantalate or lithium niobate, which adopts the following technical scheme:
a polishing composition of lithium tantalate or lithium niobate, which comprises the following components of phytate ions, silicon dioxide abrasive and the balance of water, wherein the pH value of the polishing composition is 8-11, and the pH value of the polishing composition is regulated by alkali metal hydroxide.
Preferably, the polishing composition comprises the following components of phytate ions, 10-40% by weight of silicon dioxide abrasive, and the balance of water, wherein the weight percentage of the phytate ions is not less than 0.2% and less than 2%, the pH value of the polishing composition is 8-11, and the pH value of the polishing composition is regulated by sodium hydroxide or potassium hydroxide.
Preferably, the phytate ion is obtained by dissolving a mixture of one or more of phytic acid, sodium phytate and potassium phytate in water.
Preferably, the silica abrasive is provided from a silica sol, and the z-average particle size of the silica abrasive is in the range of 50-150nm.
Preferably, the silica abrasive comprises 20% by weight of the polishing composition.
In a second aspect, the present invention provides a polishing method for lithium tantalate or lithium niobate, which adopts the following technical scheme:
A method of polishing lithium tantalate or lithium niobate comprising the steps of:
S1, dissolving phytic acid or phytate in water to obtain phytate ions, regulating the pH to be alkaline by using alkali metal hydroxide, then adding a silicon dioxide abrasive, and uniformly stirring to obtain a polishing composition, wherein the pH of a polishing solution is 8-11;
S2, providing a lithium tantalate or lithium niobate surface to be polished, introducing the polishing composition in S1 between the lithium tantalate or lithium niobate surface and the polishing surface of the polishing tool, and enabling the lithium tantalate or lithium niobate surface to be in contact with and relatively move with the polishing surface of the polishing tool.
Preferably, the weight percentage of the phytate ions in the polishing composition is not less than 0.2% and less than 2%, the weight percentage of the silica abrasive is 10-40%, the pH of the polishing composition is 8-11, and the pH of the polishing composition is adjusted by sodium hydroxide or potassium hydroxide.
Preferably, the phytate ion is obtained by dissolving a mixture of one or more of phytic acid, sodium phytate and potassium phytate in water.
Preferably, the silica abrasive is provided from a silica sol, and the z-average particle size of the silica abrasive is in the range of 50-150nm.
Preferably, the silica abrasive comprises 20% by weight of the polishing composition.
In summary, the invention has the following beneficial technical effects:
The polishing solution containing phytic acid and silica sol has a significantly higher polishing removal rate for lithium tantalate than that of the polishing solution containing sodium gluconate and silica sol, and the polishing solution disclosed by the invention has good stability and no gel.
Detailed Description
As used herein, the terms "consisting of," "comprising," "including," "having," "with," or any other variation thereof, are intended to cover a non-exclusive inclusion. For example, a process, method, article, or apparatus that comprises a list of features is not necessarily limited to only those corresponding features, but may include other features not expressly listed or inherent to such process, method, article, or apparatus.
As used herein, unless expressly stated otherwise, "or" refers to an inclusive "or" rather than an exclusive "or". For example, either condition A or B may be satisfied where A is true (or present) and B is false (or absent), A is false (or absent) and B is true (or present), and both A and B are true (or present). The present application will be described in further detail with reference to examples.
The present application will be described in further detail with reference to examples.
The invention discloses a polishing composition and a polishing method of lithium tantalate or lithium niobate.
The phytate ion can be obtained by dissolving phytic acid, sodium phytate or potassium phytate in water, the concentration of the phytate ion is preferably between 0.2 and 2 percent by weight, the effect of the phytate on enhancing the removal rate of lithium tantalate or lithium niobate is not obvious when the concentration is too low, and the risk of gel is caused when the concentration is too high.
PH the polishing composition pH is adjusted using an alkali metal hydroxide, which if adjusted with an organic base, will gel the silica sol, and if adjusted with an alkaline earth metal hydroxide, the alkaline earth metal ions may react with the phytate ions to form a precipitate. The alkali metal hydroxide is preferably sodium hydroxide or potassium hydroxide, the pH is preferably between 8 and 11, the silica sol is easy to gel when the pH is too low, and the removal rate of lithium tantalate or lithium niobate is too low when the pH is too high.
Silica abrasive the silica abrasive is a dispersion of nanoscale silica particles in water, i.e. a silica sol. The silica sol can be prepared by an ion exchange method, a silica powder method, a silane hydrolysis method, a precipitation method and the like, or can be prepared by a gas phase method, and then the silica sol is formed by mechanically dispersing nano silica powder in water. The z-average particle size of the silica abrasive in the silica sol is measured by a dynamic light scattering method, and the particle size of the silica abrasive in the silica sol is not more than 150nm, preferably not more than 120nm, and the particle size of the silica abrasive in the silica sol is not less than 50nm. Preferably not less than 100nm, the removal rate of lithium tantalate or lithium niobate is insufficient when the particle size of the silica abrasive is too small, the colloid is unstable when the particle size is too large, and the removal rate of lithium tantalate or lithium niobate is lowered. The silica abrasive may be used in combination with one or more abrasives having a z-average particle size of between 50nm and 150 nm.
The water is not particularly required, and tap water, distilled water, deionized water or water purified by other methods can be selected according to the application.
The polishing method comprises the steps of introducing the polishing solution between the surface of lithium tantalate or lithium niobate to be polished and a polishing pad, and enabling the surface to be polished to be in contact with the polishing pad and to move relatively. The polishing pad is preferably a medium-hardness polishing pad with a Shore hardness of 60-90C, and more preferably a polyurethane-impregnated non-woven polishing pad with a Shore hardness of 80-90C. Too low a hardness of the polishing pad results in a low removal rate and too high a hardness results in a risk of scratches. The polishing pressure is preferably between 100g/cm2 and 400g/cm2, more preferably between 150g/cm2 and 300g/cm2, and too small a pressure results in too low a removal rate, and too large a friction force results in abnormal sound and unstable machine during polishing.
The polishing methods of the following examples and comparative examples were carried out using a single-sided polisher with a large disc diameter of 380mm, the polishing pad being a polyurethane-impregnated nonwoven polishing pad having a Shore hardness of 85-88C, the polishing pad having XY grooves, each square being about 10mm x 10mm, a space groove width of about 2mm, and a groove depth of about 0.8mm. 1 piece of 4 inch lithium tantalate or lithium niobate substrate sheet is thrown each time, the pressure is 191g/cm2, the rotating speed of a large disc is 100rpm, the flow rate of polishing solution is 60ml/min, the polishing time is 5 minutes, and the removal amount is measured by an electronic balance with the precision of 0.1 mg.
Examples
Example 1
20 G of phytic acid solution with the weight content of 50% is mixed with 480 g of deionized water, the pH is adjusted to 8.57 by potassium hydroxide, 500 g of silica sol with the solid content of 40% and the z-average particle size of 100nm measured by a dynamic light scattering method is added, the pH of the obtained polishing solution is 9.16, the content of phytate ions is 1wt% and the content of the silica abrasive is 20wt%. The weight of the polished lithium tantalate was 27.2mg. The polishing solution is placed in an oven at 45 ℃ for 30 days, and the polishing solution has good fluidity and does not gel.
Example 2
The pH of the phytic acid solution with the weight content of 50% is adjusted to 8.5 by potassium hydroxide, 4 g of silica sol with the solid content of 40% and the z-average particle diameter of the silica abrasive of 50 nm measured by a dynamic light scattering method is taken, the pH of the obtained polishing solution is 9.76, the content of the phytate ions is 0.2wt%, and the content of the silica abrasive is about 40wt%. The weight of the polished lithium tantalate was 25.9mg. The polishing solution is placed in an oven at 45 ℃ for 30 days, and the polishing solution has good fluidity and does not gel.
Example 3
20 G of a phytic acid solution with a weight content of 50% is mixed with 730 g of deionized water, the pH is adjusted to 8.51 by potassium hydroxide, 250 g of silica sol with a solid content of 40% and a z-average particle size of 150 nm as measured by a dynamic light scattering method is added, at this time, the pH of the obtained polishing solution is 8.82, the content of phytate ions is 1wt%, and the content of the silica abrasive is 10wt%. The weight of the polished lithium tantalate was 19.6mg. The polishing solution is placed in an oven at 45 ℃ for 30 days, and the polishing solution has good fluidity and does not gel.
Example 4
20 G of phytic acid solution with the weight content of 50% is mixed with 480 g of deionized water, the pH is adjusted to 12.5 by sodium hydroxide, 500 g of silica sol with the solid content of 40% and the z-average particle size of 120 nm measured by a dynamic light scattering method is added, the pH of the obtained polishing solution is 10.98, the content of phytate ions is 1wt% and the content of the silica abrasive is 20wt%. The weight of the polished lithium tantalate was 24.7mg. The polishing solution is placed in an oven at 45 ℃ for 30 days, and the polishing solution has good fluidity and does not gel.
Example 5
20 G of phytic acid solution with the weight content of 50% is mixed with 480 g of deionized water, the pH is adjusted to 12.5 by sodium hydroxide, 500 g of silica sol with the solid content of 40% and the z-average particle size of 120 nm measured by a dynamic light scattering method is added, the pH of the obtained polishing solution is 10.98, the content of phytate ions is 1wt% and the content of the silica abrasive is 20wt%. The weight of the polished lithium niobate was 37.3mg. The polishing solution is placed in an oven at 45 ℃ for 30 days, and the polishing solution has good fluidity and does not gel.
Comparative example
Comparative example 1
500 G of deionized water was added to 500 g of silica sol having a solid content of 40% and a silica abrasive z-average particle diameter of 100 nm as measured by a dynamic light scattering method, and the pH was adjusted to 9.21 with nitric acid, at which time the obtained polishing liquid contained 20wt% of the silica abrasive. The weight of the polished lithium tantalate was 17.4mg.
Comparative example 2
10G of sodium gluconate is dissolved in 490 g of deionized water, 500g of silica sol with a solid content of 40% and a z-average particle size of 100 nm as measured by a dynamic light scattering method is added, and the pH of the obtained polishing solution is 9.22, the sodium gluconate content is 1wt% and the silica abrasive content is 20wt%. The weight of the polished lithium tantalate was 21.0mg.
Comparative example 3
20G of an aqueous solution of aminotrimethylene phosphonic acid having a weight content of 50% was added to 480 g of deionized water, the pH was adjusted to 8.55 with potassium hydroxide, and 500 g of silica sol having a solid content of 40% and a z-average particle diameter of 100 nm as measured by a dynamic light scattering method was added, whereby the pH of the obtained polishing liquid was 9.30, the aminotrimethylene phosphonate content was 1% by weight, and the silica abrasive content was 20% by weight. The weight of the polished lithium tantalate was 28.1mg. The slurry was placed in an oven at 45 ℃ and gelled for 7 days.
Comparative example 4
17 G of an aqueous solution of hydroxyethylidene diphosphonate having a weight content of 60% was added to 483 g of deionized water, the pH was adjusted to 8.50 with potassium hydroxide, and 500 g of silica sol having a solid content of 40% and a z-average particle diameter of 100 nm as measured by a dynamic light scattering method was added, whereby the pH of the resulting polishing liquid was 9.15, the content of hydroxyethylidene diphosphonate was 1% by weight, and the content of silica abrasive was 20% by weight. The weight of the polished lithium tantalate was 27.4mg. The slurry was placed in an oven at 45 ℃ and gelled for 7 days.
Comparative example 5
10 G of ethylenediamine tetramethylene phosphonic acid is dissolved in 490 g of deionized water, the pH is adjusted to 8.51 by potassium hydroxide, 500 g of silica sol with a solid content of 40% and a z-average particle diameter of 100 nm as measured by a dynamic light scattering method is added, at this time, the pH of the obtained polishing solution is 9.23, the ethylenediamine tetramethylene phosphonic acid radical content is 1wt% and the silica abrasive content is 20wt%. The weight of the polished lithium tantalate was 26.4mg. The slurry was placed in an oven at 45 ℃ and gelled for 7 days.
Comparative example 6
20 G of 50% by weight of diethylenetriamine penta-methylene phosphonic acid aqueous solution are added into 480 g of deionized water, the pH is adjusted to 8.49 by potassium hydroxide, 500 g of silica sol with a solid content of 40% and a z-average particle size of 100nm as measured by a dynamic light scattering method are added, the pH of the obtained polishing solution is 9.09, the content of diethylenetriamine penta-methylene phosphonic acid radical is 1wt% and the content of silica abrasive is 20wt%. The weight of the polished lithium tantalate was 27.1mg. The slurry was placed in an oven at 45 ℃ and gelled for 7 days.
Comparative example 7
20 G of a phytic acid solution with a weight content of 50% is mixed with 448 g of deionized water, the pH is adjusted to 8.50 by potassium hydroxide, 500 g of silica sol with a solid content of 40% and a z-average particle size of 100 nm as measured by a dynamic light scattering method is added, the pH of the obtained polishing solution is 9.08, and 32 g of a 31.5% hydrogen peroxide solution is added. At this time, the polishing solution contains 1wt% of phytate ions, 20wt% of silicon dioxide abrasive materials and 1wt% of hydrogen peroxide. The weight of the polished lithium tantalate was 20.5mg.
Comparative example 8
20 G of phytic acid solution with the weight content of 50% is mixed with 480 g of deionized water, the pH is adjusted to 8.49 by sodium hydroxide, 500 g of silica sol with the solid content of 40% and the z-average particle size of the silica abrasive of 25 nanometers measured by a dynamic light scattering method is added, the pH of the obtained polishing solution is 9.10, the content of phytate ions is 1wt% and the content of the silica abrasive is 20wt%. The weight of the polished lithium tantalate was 14.3mg.
Comparative example 9
10G of sodium citrate was dissolved in 490 g of deionized water, and 500 g of silica sol having a solids content of 40% and a z-average particle diameter of 100 nm as measured by dynamic light scattering was added, and the pH was adjusted to 8.56 with nitric acid. The polishing solution was put into an oven at 45 ℃ and gelled for 1 day.
Comparative example 10
20 G of a phytic acid solution with a weight content of 50% was mixed with 480 g of deionized water, the pH was adjusted to about 8.5 with tetramethylammonium hydroxide, and 500 g of silica sol with a solid content of 40% and a silica abrasive z-average particle diameter of 100 nm as measured by a dynamic light scattering method was added, at which time the pH of the obtained polishing solution was 9.24, the content of phytate ions was 1wt%, and the content of silica abrasive was 20wt%. The polishing solution was placed in an oven at 45 ℃ for 2 days to gel.
Comparative example 11
20G of a phytic acid solution with a weight content of 50% is mixed with 480 g of deionized water, the pH is adjusted to about 8.5 by using triethanolamine, 500g of silica sol with a solid content of 40% and a z-average particle size of 100nm as measured by a dynamic light scattering method is added, the pH of the obtained polishing solution is 8.54, the content of phytate ions is 1wt%, and the content of the silica abrasive is 20wt%. The polishing solution was placed in an oven at 45 ℃ and after 4 days the bottom was visible as a gel and after 9 days the gel was complete.
Comparative example 12
20 G of a phytic acid solution having a weight content of 50% was mixed with 480 g of deionized water, the pH was adjusted to about 8.5 with 1, 3-tetramethylguanidine, and 500 g of silica sol having a solid content of 40% and a silica abrasive z-average particle diameter of 100 nm as measured by a dynamic light scattering method was added, at which time the pH of the obtained polishing solution was 9.17, the content of phytate ions was 1% by weight, and the content of silica abrasive was 20% by weight. The polishing solution was placed in an oven at 45 ℃ and gelled after 2 days.
Comparative example 13
40 G of a phytic acid solution with a weight content of 50% is mixed with 460 g of deionized water, the pH is adjusted to about 8.5 by sodium hydroxide, 500 g of silica sol with a solid content of 40% and a z-average particle diameter of 100nm measured by a dynamic light scattering method is added, the pH of the obtained polishing solution is 8.94, the content of phytate ions is 2wt%, and the content of the silica abrasive is 20wt%. The polishing solution was placed in an oven at 45 ℃ and gelled after 2 days. This example illustrates that the phytic acid concentration is less than 2%.
Comparative example 14
20G of a phytic acid solution with a weight content of 50% is mixed with 480 g of deionized water, the pH is adjusted to about 5.5 by sodium hydroxide, 500 g of silica sol with a solid content of 40% and a z-average particle diameter of 100 nm as measured by a dynamic light scattering method is added, at this time, the pH of the obtained polishing solution is 5.89, the content of phytate ions is 1wt%, and the content of the silica abrasive is 20wt%. The polishing solution was put in an oven at 45 ℃ and gelled after 1 day.
Comparative example 15
20G of a phytic acid solution with a weight content of 50% is mixed with 480 g of deionized water, the pH is adjusted to about 3.5 by sodium hydroxide, 500 g of silica sol with a solid content of 40% and a z-average particle diameter of 100 nm as measured by a dynamic light scattering method is added, the pH of the obtained polishing solution is 3.97, the content of phytate ions is 1wt% and the content of the silica abrasive is 20wt%. The polishing solution was placed in an oven at 45 ℃ and gelled after 2 days.
Polishing test data recording table
TABLE 1 component content and test data for examples 1-4 and comparative examples 1-15
From example 1 and comparative example 1, it is evident that the phytate ion significantly increases the removal rate of lithium tantalate by polishing, and the slurry is stable in colloid, and no gelation occurs when heated at 45 ℃ for 30 days.
Comparative example 2 reproduces the results of the prior art with patent publication number CN1782014a, and it is known from example 1 and comparative example 2 that the phytate can significantly increase the polishing removal rate of lithium tantalate compared to gluconate.
As is clear from examples 1 and comparative examples 3 to 6, although various organic phosphonic acids can increase the removal rate of lithium tantalate polishing, they can cause instability of silica sol and gel, while polishing solutions using phytic acid do not appear, indicating that phytic acid has little effect on stability of silica sol.
As is clear from examples 1 and 7, the removal rate of lithium tantalate was rather decreased by adding an oxidizing agent such as hydrogen peroxide.
As is clear from comparative example 8, when the particle size of the silica abrasive is too small, the removal rate of lithium tantalate is significantly reduced.
Comparative example 9 reproduces the results of the prior art of patent No. JP6481589B2, illustrating that the use of sodium citrate results in a polishing liquid gel.
As is evident from comparative examples 10 to 12, the polishing liquid was gelled when the pH was adjusted with an organic base.
As is clear from comparative example 13, when the phytic acid ion concentration reaches 2%, the polishing liquid becomes gel.
As is evident from comparative examples 14 to 15, the gel state occurs when the polishing liquid is acidic.
While the invention has been described with reference to the preferred embodiments, it will be understood by those skilled in the art that the present invention is not limited thereto, and that the invention is not limited thereto, but is intended to be limited thereto, when the technical content disclosed above is utilized to make a little change or modification into equivalent embodiments of equivalent changes, but the technical content of the invention is not deviated from, any simple modification, equivalent changes and modification of the above embodiments are all within the scope of the technical solution of the invention.