Curium is a hard, dense, silvery metal with a high melting and boiling point for an actinide. It isparamagnetic atambient conditions, but becomesantiferromagnetic upon cooling, and other magnetic transitions are also seen in many curium compounds. In compounds, curium usually hasvalence +3 and sometimes +4; the +3 valence is predominant in solutions. Curium readily oxidizes, and its oxides are a dominant form of this element. It forms stronglyfluorescent complexes with various organic compounds. If it gets into the human body, curium accumulates in bones, lungs, and liver, where it promotescancer.
The sample was prepared as follows: firstplutonium nitrate solution was coated on aplatinum foil of ~0.5 cm2 area, the solution was evaporated and the residue was converted intoplutonium(IV) oxide (PuO2) byannealing. Following cyclotron irradiation of the oxide, the coating was dissolved withnitric acid and then precipitated as the hydroxide using concentrated aqueousammonia solution. The residue was dissolved inperchloric acid, and further separation was done byion exchange to yield a certain isotope of curium. The separation of curium and americium was so painstaking that the Berkeley group initially called those elementspandemonium (from Greek forall demons orhell) anddelirium (from Latin formadness).[9][10]
Curium-242 was made in July–August 1944 by bombarding239Pu withα-particles to produce curium with the release of aneutron:[7][11]
Curium-242 was unambiguously identified by the characteristic energy of the α-particles emitted during the decay:
Thehalf-life of thisalpha decay was first measured as 5 months (150 days)[7] and then corrected to 162.8 days.[5]
Another isotope240Cm was produced in a similar reaction in March 1945:
The α-decay half-life of240Cm was determined as 26.8 days[7] and later revised to 30.4 days.[5]
The discovery of curium and americium in 1944 was closely related to theManhattan Project, so the results were confidential and declassified only in 1945. Seaborg leaked the synthesis of the elements 95 and 96 on the U.S. radio show for children, theQuiz Kids, five days before the official presentation at anAmerican Chemical Society meeting on November 11, 1945, when one listener asked if any new transuranic element beside plutonium andneptunium had been discovered during the war.[9] The discovery of curium (242Cm and240Cm), its production, and its compounds was later patented listing only Seaborg as the inventor.[12]
As the name for the element of atomic number 96 we should like to propose "curium", with symbol Cm. The evidence indicates that element 96 contains seven 5f electrons and is thus analogous to the element gadolinium, with its seven 4f electrons in the regular rare earth series. On this basis element 96 is named after the Curies in a manner analogous to the naming of gadolinium, in which the chemist Gadolin was honored.[7]
The first curium samples were barely visible, and were identified by their radioactivity. Louis Werner andIsadore Perlman made the first substantial sample of 30 μg curium-242 hydroxide at University of California, Berkeley in 1947 by bombardingamericium-241 with neutrons.[14][15][16] Macroscopic amounts ofcurium(III) fluoride were obtained in 1950 by W. W. T. Crane, J. C. Wallmann and B. B. Cunningham. Its magnetic susceptibility was very close to that of GdF3 providing the first experimental evidence for the +3 valence of curium in its compounds.[14] Curium metal was produced only in 1950 by reduction of CmF3 withbarium.[17][18]
Double-hexagonal close packing with the layer sequence ABAC in the crystal structure of α-curium (A: green, B: blue, C: red)Photoluminescence of the Cm(HDPA)3·H2O crystal uponirradiation with 420 nm light
A synthetic, radioactive element, curium is a hard, dense metal with a silvery-white appearance and physical and chemical properties resemblinggadolinium. Its melting point of 1344 °C is significantly higher than that of the previous elements neptunium (637 °C), plutonium (639 °C) and americium (1176 °C). In comparison, gadolinium melts at 1312 °C. Curium boils at 3556 °C. With a density of 13.52 g/cm3, curium is lighter than neptunium (20.45 g/cm3) and plutonium (19.8 g/cm3), but heavier than most other metals. Of two crystalline forms of curium, α-Cm is more stable at ambient conditions. It has a hexagonal symmetry,space group P63/mmc, lattice parametersa = 365 pm andc = 1182 pm, and fourformula units perunit cell.[19] The crystal consists of double-hexagonal close packing with the layer sequence ABAC and so is isotypic with α-lanthanum. At pressure >23 GPa, at room temperature, α-Cm becomes β-Cm, which hasface-centered cubic symmetry, space group Fm3m and lattice constanta = 493 pm.[19] On further compression to 43 GPa, curium becomes anorthorhombic γ-Cm structure similar to α-uranium, with no further transitions observed up to 52 GPa. These three curium phases are also called Cm I, II and III.[20][21]
Curium has peculiar magnetic properties. Its neighbor element americium shows no deviation fromCurie-Weissparamagnetism in the entire temperature range, but α-Cm transforms to anantiferromagnetic state upon cooling to 65–52 K,[22][23] and β-Cm exhibits aferrimagnetic transition at ~205 K. Curium pnictides showferromagnetic transitions upon cooling:244CmN and244CmAs at 109 K,248CmP at 73 K and248CmSb at 162 K. The lanthanide analog of curium, gadolinium, and its pnictides, also show magnetic transitions upon cooling, but the transition character is somewhat different: Gd and GdN become ferromagnetic, and GdP, GdAs and GdSb show antiferromagnetic ordering.[24]
In accordance with magnetic data, electrical resistivity of curium increases with temperature – about twice between 4 and 60 K – and then is nearly constant up to room temperature. There is a significant increase in resistivity over time (~10 μΩ·cm/h) due to self-damage of the crystal lattice by alpha decay. This makes uncertain the true resistivity of curium (~125 μΩ·cm). Curium's resistivity is similar to that of gadolinium, and the actinides plutonium and neptunium, but significantly higher than that of americium, uranium,polonium andthorium.[4]
Under ultraviolet illumination, curium(III) ions show strong and stable yellow-orangefluorescence with a maximum in the range of 590–640 nm depending on their environment.[25] The fluorescence originates from the transitions from the first excited state6D7/2 and the ground state8S7/2. Analysis of this fluorescence allows monitoring interactions between Cm(III) ions in organic and inorganic complexes.[26]
Curium ion in solution almost always has a +3oxidation state, the most stable oxidation state for curium.[27] A +4 oxidation state is seen mainly in a few solid phases, such as CmO2 and CmF4.[28][29] Aqueous curium(IV) is only known in the presence of strong oxidizers such aspotassium persulfate, and is easily reduced to curium(III) byradiolysis and even by water itself.[30] The chemical behavior of curium is different from the actinides thorium and uranium, and is similar to americium and manylanthanides. In aqueous solution, the Cm3+ ion is colorless to pale green;[31] Cm4+ ion is pale yellow.[32] The optical absorption of Cm3+ ion contains three sharp peaks at 375.4, 381.2 and 396.5 nm and their strength can be directly converted into the concentration of the ions.[33] The +6 oxidation state has only been reported once in solution in 1978, as the curyl ion (CmO2+ 2): this was prepared frombeta decay ofamericium-242 in the americium(V) ion242 AmO+ 2.[2] Failure to get Cm(VI) from oxidation of Cm(III) and Cm(IV) may be due to the high Cm4+/Cm3+ionization potential and the instability of Cm(V).[30]
About 19radioisotopes and 7nuclear isomers,233Cm to251Cm, are known; none arestable. The longest half-lives are 15.6 million years (247Cm) and 348,000 years (248Cm). Other long-lived ones are250Cm (~8300 years),245Cm (8250 years), and246Cm (4706 years). Curium-250 is unusual: it mainly decays byspontaneous fission (only mode observed).[5] The most common isotopes are242Cm and244Cm with the half-lives 162.8 days and 18.11 years, respectively.
All isotopes ranging from242Cm to248Cm, as well as250Cm, undergo a self-sustainingnuclear chain reaction and thus in principle can be anuclear fuel in a reactor. As in most transuranic elements,nuclear fission cross section is especially high for the odd-mass curium isotopes243Cm,245Cm and247Cm. These can be used inthermal-neutron reactors, whereas a mixture of curium isotopes is only suitable forfast breeder reactors since the even-mass isotopes are not fissile in a thermal reactor and accumulate as burn-up increases.[40] The mixed-oxide (MOX) fuel, which is to be used in power reactors, should contain little or no curium becauseneutron activation of248Cm will createcalifornium. Californium is a strongneutron emitter, and would pollute the back end of the fuel cycle and increase the dose to reactor personnel. Hence, ifminor actinides are to be used as fuel in a thermal neutron reactor, the curium should be excluded from the fuel or placed in special fuel rods where it is the only actinide present.[41]
Transmutation flow between238Pu and244Cm in LWR.[42] Fission percentage is 100 minus shown percentages. Total rate of transmutation varies greatly by nuclide. 245Cm–248Cm are long-lived with negligible decay.
The adjacent table lists thecritical masses for curium isotopes for a sphere, without moderator or reflector. With a metal reflector (30 cm of steel), the critical masses of the odd isotopes are about 3–4 kg. When using water (thickness ~20–30 cm) as the reflector, the critical mass can be as small as 59 grams for245Cm, 155 grams for243Cm and 1550 grams for247Cm. There is significant uncertainty in these critical mass values. While it is usually on the order of 20%, the values for242Cm and246Cm were listed as large as 371 kg and 70.1 kg, respectively, by some research groups.[40][43]
Curium is not currently used as nuclear fuel due to its low availability and high price.[44]245Cm and247Cm have very small critical mass and so could be used intactical nuclear weapons, but none are known to have been made. Curium-243 is not suitable for such, due to its short half-life and strong α emission, which would cause excessive heat.[45] Curium-247 would be highly suitable due to its long half-life, which is 647 times longer thanplutonium-239 (used in many existingnuclear weapons).
Several isotopes of curium were detected in the fallout from theIvy Mike nuclear test.
The longest-lived isotope,247Cm, has half-life 15.6 million years; so anyprimordial curium, that is, present on Earth when it formed, should have decayed by now. Its past presence as anextinct radionuclide is detectable as an excess of its primordial, long-lived daughter235U.[46] Traces of242Cm may occur naturally in uranium minerals due to neutron capture and beta decay (238U →239Pu →240Pu →241Am →242Cm), though the quantities would be tiny and this has not been confirmed: even with "extremely generous" estimates for neutron absorption possibilities, the quantity of242Cm present in 1 × 108 kg of 18% uranium pitchblende would not even be one atom.[47][48][49] Traces of247Cm are also probably brought to Earth incosmic rays, but this also has not been confirmed.[47] There is also the possibility of244Cm being produced as thedouble beta decay daughter of natural244Pu.[47][50]
Atmospheric curium compounds are poorly soluble in common solvents and mostly adhere to soil particles. Soil analysis revealed about 4,000 times higher concentration of curium at the sandy soil particles than in water present in the soil pores. An even higher ratio of about 18,000 was measured inloam soils.[55]
The transuranic elements up tofermium, including curium, should have been present in thenatural nuclear fission reactor atOklo, but any quantities produced then would have long since decayed away.[56]
Curium is made in small amounts innuclear reactors, and by now only kilograms of242Cm and244Cm have been accumulated, and grams or even milligrams for heavier isotopes. Hence the high price of curium, which has been quoted at 160–185USD per milligram,[14] with a more recent estimate at US$2,000/g for242Cm and US$170/g for244Cm.[57] In nuclear reactors, curium is formed from238U in a series of nuclear reactions. In the first chain,238U captures a neutron and converts into239U, which viaβ− decay transforms into239Np and239Pu.
Further neutron capture followed by β−-decay givesamericium (241Am) which further becomes242Cm:
.
2
For research purposes, curium is obtained by irradiating not uranium but plutonium, which is available in large amounts from spent nuclear fuel. A much higher neutron flux is used for the irradiation that results in a different reaction chain and formation of244Cm:[8]
3
Curium-244 alpha decays to240Pu, but it also absorbs neutrons, hence a small amount of heavier curium isotopes. Of those,247Cm and248Cm are popular in scientific research due to their long half-lives. But the production rate of247Cm in thermal neutron reactors is low because it is prone to fission due to thermal neutrons.[58] Synthesis of250Cm byneutron capture is unlikely due to the short half-life of the intermediate249Cm (64 min), which β− decays to theberkelium isotope249Bk.[58]
4
The above cascade of (n,γ) reactions gives a mix of different curium isotopes. Their post-synthesis separation is cumbersome, so a selective synthesis is desired. Curium-248 is favored for research purposes due to its long half-life. The most efficient way to prepare this isotope is by α-decay of thecalifornium isotope252Cf, which is available in relatively large amounts due to its long half-life (2.65 years). About 35–50 mg of248Cm is produced thus, per year. The associated reaction produces248Cm with isotopic purity of 97%.[58]
5
Another isotope,245Cm, can be obtained for research, from α-decay of249Cf; the latter isotope is produced in small amounts from β−-decay of249Bk.
Chromatographicelution curves revealing the similarity between Tb, Gd, Eu lanthanides and corresponding Bk, Cm, Am actinides
Most synthesis routines yield a mix of actinide isotopes asoxides, from which a given isotope of curium needs to be separated. An example procedure could be to dissolve spent reactor fuel (e.g.MOX fuel) innitric acid, and remove the bulk of the uranium and plutonium using aPUREX (Plutonium –URaniumEXtraction) type extraction withtributyl phosphate in a hydrocarbon. The lanthanides and the remaining actinides are then separated from the aqueous residue (raffinate) by a diamide-based extraction to give, after stripping, a mixture of trivalent actinides and lanthanides. A curium compound is then selectively extracted using multi-stepchromatographic and centrifugation techniques with an appropriate reagent.[59]Bis-triazinyl bipyridine complex has been recently proposed as such reagent which is highly selective to curium.[60] Separation of curium from the very chemically similar americium can also be done by treating a slurry of their hydroxides in aqueoussodium bicarbonate withozone at elevated temperature. Both americium and curium are present in solutions mostly in the +3 valence state; americium oxidizes to soluble Am(IV) complexes, but curium stays unchanged and so can be isolated by repeated centrifugation.[61]
Metallic curium is obtained byreduction of its compounds. Initially, curium(III) fluoride was used for this purpose. The reaction was done in an environment free of water and oxygen, in an apparatus made oftantalum andtungsten, using elementalbarium orlithium as reducing agents.[8][17][62][63][64]
Curium readily reacts with oxygen forming mostly Cm2O3 and CmO2 oxides,[53] but the divalent oxide CmO is also known.[66] Black CmO2 can be obtained by burning curiumoxalate (Cm 2(C 2O 4) 3), nitrate (Cm(NO 3) 3), or hydroxide in pure oxygen.[29][67] Upon heating to 600–650 °C in vacuum (about 0.01 Pa), it transforms into the whitish Cm2O3:[29][68]
4CmO2 → 2Cm2O3 + O2.
Or, Cm2O3 can be obtained by reducing CmO2 with molecularhydrogen:[69]
2CmO2 + H2 → Cm2O3 + H2O
Also, a number of ternary oxides of the type M(II)CmO3 are known, where M stands for a divalent metal, such as barium.[70]
Thermal oxidation of trace quantities of curium hydride (CmH2–3) has been reported to give a volatile form of CmO2 and the volatile trioxide CmO3, one of two known examples of the very rare +6 state for curium.[2] Another observed species was reported to behave similar to a supposed plutonium tetroxide and was tentatively characterized as CmO4, with curium in the extremely rare +8 state;[71] but new experiments seem to indicate that CmO4 does not exist, and have cast doubt on the existence of PuO4 as well.[72]
The colorless curium(III) fluoride (CmF3) can be made by adding fluoride ions into curium(III)-containing solutions. The brown tetravalent curium(IV) fluoride (CmF4) on the other hand is only obtained by reacting curium(III) fluoride with molecularfluorine:[8]
2 CmF3 + F2 → 2 CmF4
A series of ternary fluorides are known of the form A7Cm6F31 (A =alkali metal).[73]
The colorlesscurium(III) chloride (CmCl3) is made by reactingcurium hydroxide (Cm(OH)3) with anhydroushydrogen chloride gas. It can be further turned into other halides such as curium(III) bromide (colorless to light green) andcurium(III) iodide (colorless), by reacting it with theammonia salt of the corresponding halide at temperatures of ~400–450 °C:[74]
CmCl3 + 3 NH4I → CmI3 + 3 NH4Cl
Or, one can heat curium oxide to ~600°C with the corresponding acid (such ashydrobromic for curium bromide).[75][76] Vapor phasehydrolysis of curium(III) chloride gives curium oxychloride:[77]
Sulfides, selenides and tellurides of curium have been obtained by treating curium with gaseoussulfur,selenium ortellurium in vacuum at elevated temperature.[78][79] Curiumpnictides of the type CmX are known fornitrogen,phosphorus,arsenic andantimony.[8] They can be prepared by reacting either curium(III) hydride (CmH3) or metallic curium with these elements at elevated temperature.[80]
Organometallic complexes analogous touranocene are known also for other actinides, such as thorium, protactinium, neptunium, plutonium and americium.Molecular orbital theory predicts a stable "curocene" complex (η8-C8H8)2Cm, but it has not been reported experimentally yet.[81][82]
Formation of the complexes of the typeCm(n-C 3H 7-BTP) 3 (BTP = 2,6-di(1,2,4-triazin-3-yl)pyridine), in solutions containing n-C3H7-BTP and Cm3+ ions has been confirmed byEXAFS. Some of these BTP-type complexes selectively interact with curium and thus are useful for separating it from lanthanides and another actinides.[25][83] Dissolved Cm3+ ions bind with many organic compounds, such ashydroxamic acid,[84]urea,[85]fluorescein[86] andadenosine triphosphate.[87] Many of these compounds are related to biological activity of variousmicroorganisms. The resulting complexes show strong yellow-orange emission under UV light excitation, which is convenient not only for their detection, but also for studying interactions between the Cm3+ ion and the ligands via changes in the half-life (of the order ~0.1 ms) and spectrum of the fluorescence.[26][84][85][86][87]
Ionized air glow from curium alpha-radiation creates a purple aura in the dark.
Curium is one of the most radioactive isolable elements. Its two most common isotopes242Cm and244Cm are strong alpha emitters (energy 6 MeV); they have fairly short half-lives, 162.8 days and 18.1 years, and give as much as 120 W/g and 3 W/g of heat, respectively.[14][91][92] Therefore, curium can be used in its common oxide form inradioisotope thermoelectric generators like those in spacecraft. This application has been studied for the244Cm isotope, while242Cm was abandoned due to its prohibitive price, around 2000 USD/g.243Cm with a ~30-year half-life and good energy yield of ~1.6 W/g could be a suitable fuel, but it gives significant amounts of harmfulgamma andbeta rays from radioactive decay products. As an α-emitter,244Cm needs much less radiation shielding, but it has a high spontaneous fission rate, and thus a lot of neutron and gamma radiation. Compared to a competing thermoelectric generator isotope such as238Pu,244Cm emits 500 times more neutrons, and its higher gamma emission requires a shield that is 20 times thicker—2 inches (51 mm) of lead for a 1 kW source, compared to 0.1 inches (2.5 mm) for238Pu. Therefore, this use of curium is currently considered impractical.[57]
A more promising use of242Cm is for making238Pu, a better radioisotope for thermoelectric generators such as in heart pacemakers. The alternate routes to238Pu use the (n,γ) reaction of237Np, ordeuteron bombardment of uranium, though both reactions always produce236Pu as an undesired by-product since the latter decays to232U with strong gamma emission.[93] Curium is a common starting material for making highertransuranic andsuperheavy elements. Thus, bombarding248Cm with neon (22Ne), magnesium (26Mg), or calcium (48Ca) yields isotopes ofseaborgium (265Sg),hassium (269Hs and270Hs), andlivermorium (292Lv,293Lv, and possibly294Lv).[94] Californium was discovered when a microgram-sized target of curium-242 was irradiated with 35 MeValpha particles using the 60-inch (150 cm) cyclotron at Berkeley:
242 96Cm +4 2He →245 98Cf +1 0n
Only about 5,000 atoms of californium were produced in this experiment.[95]
The odd-mass curium isotopes243Cm,245Cm, and247Cm are all highlyfissile and can release additional energy in a thermal spectrumnuclear reactor. All curium isotopes are fissionable in fast-neutron reactors. This is one of the motives forminor actinide separation and transmutation in thenuclear fuel cycle, helping to reduce the long-term radiotoxicity of used, orspent nuclear fuel.[citation needed]
Alpha-particle X-ray spectrometer of a Mars exploration rover
An elaborate APXS setup has a sensor head containing six curium sources with a total decay rate of several tens ofmillicuries (roughly onegigabecquerel). The sources are collimated on a sample, and the energy spectra of the alpha particles and protons scattered from the sample are analyzed (proton analysis is done only in some spectrometers). These spectra contain quantitative information on all major elements in the sample except for hydrogen, helium and lithium.[100]
Due to its radioactivity, curium and its compounds must be handled in appropriate labs under special arrangements. While curium itself mostly emits α-particles which are absorbed by thin layers of common materials, some of its decay products emit significant fractions of beta and gamma rays, which require a more elaborate protection.[53] If consumed, curium is excreted within a few days and only 0.05% is absorbed in the blood. From there, ~45% goes to theliver, 45% to the bones, and the remaining 10% is excreted. In bone, curium accumulates on the inside of the interfaces to thebone marrow and does not significantly redistribute with time; its radiation destroys bone marrow and thus stopsred blood cell creation. Thebiological half-life of curium is about 20 years in the liver and 50 years in the bones.[53][55] Curium is absorbed in the body much more strongly via inhalation, and the allowed total dose of244Cm in soluble form is 0.3 μCi.[14] Intravenous injection of242Cm- and244Cm-containing solutions to rats increased the incidence ofbone tumor, and inhalation promotedlung andliver cancer.[53]
Curium isotopes are inevitably present in spent nuclear fuel (about 20 g/tonne).[101] The isotopes245Cm–248Cm have decay times of thousands of years and must be removed to neutralize the fuel for disposal.[102] Such a procedure involves several steps, where curium is first separated and then converted by neutron bombardment in special reactors to short-lived nuclides. This procedure,nuclear transmutation, while well documented for other elements, is still being developed for curium.[25]
^abcdeSeaborg, Glenn T.; James, R. A.; Ghiorso, A. (1949)."The New Element Curium (Atomic Number 96)"(PDF).NNES PPR (National Nuclear Energy Series, Plutonium Project Record). The Transuranium Elements: Research Papers, Paper No. 22.2.14 B.OSTI4421946. Archived fromthe original(PDF) on 12 October 2007.
^abcdeMorss, L. R.; Edelstein, N. M. and Fugere, J. (eds):The Chemistry of the Actinide Elements and transactinides, volume 3, Springer-Verlag, Dordrecht 2006,ISBN1-4020-3555-1.
^abcdeHammond C. R. "The elements" inLide, D. R., ed. (2005).CRC Handbook of Chemistry and Physics (86th ed.). Boca Raton, Florida: CRC Press.ISBN0-8493-0486-5.
^L. B. Werner, I. Perlman: "Isolation of Curium", NNES PPR (National Nuclear Energy Series, Plutonium Project Record), Vol. 14 B,The Transuranium Elements: Research Papers, Paper No. 22.5, McGraw-Hill Book Co., Inc., New York, 1949.
^Haire, R.; Peterson, J.; Benedict, U.; Dufour, C.; Itie, J. (1985). "X-ray diffraction of curium-248 metal under pressures of up to 52 GPa".Journal of the Less Common Metals.109 (1): 71.doi:10.1016/0022-5088(85)90108-0.
^abcDenecke, Melissa A.; Rossberg, André; Panak, Petra J.; Weigl, Michael; Schimmelpfennig, Bernd; Geist, Andreas (2005). "Characterization and Comparison of Cm(III) and Eu(III) Complexed with 2,6-Di(5,6-dipropyl-1,2,4-triazin-3-yl)pyridine Using EXAFS, TRFLS, and Quantum-Chemical Methods".Inorganic Chemistry.44 (23):8418–8425.doi:10.1021/ic0511726.PMID16270980.
^abBünzli, J.-C. G. and Choppin, G. R.Lanthanide probes in life, chemical, and earth sciences: theory and practice, Elsevier, Amsterdam, 1989ISBN0-444-88199-9
^abcAsprey, L. B.; Ellinger, F. H.; Fried, S.; Zachariasen, W. H. (1955). "Evidence for Quadrivalent Curium: X-Ray Data on Curium Oxides1".Journal of the American Chemical Society.77 (6): 1707.Bibcode:1955JAChS..77.1707A.doi:10.1021/ja01611a108.
^Earth, Live Science Staff 2013-09-24T21:44:13Z Planet (24 September 2013)."Facts About Curium".livescience.com. Retrieved2019-08-10.{{cite web}}: CS1 maint: numeric names: authors list (link)
^Emsley, John (2011).Nature's Building Blocks: An A-Z Guide to the Elements (New ed.). New York, NY: Oxford University Press.ISBN978-0-19-960563-7.
^abBasic elements of static RTGsArchived 2013-02-15 at theWayback Machine, G.L. Kulcinski, NEEP 602 Course Notes (Spring 2000), Nuclear Power in Space, University of Wisconsin Fusion Technology Institute (see last page)
^abcLumetta, Gregg J.; Thompson, Major C.; Penneman, Robert A.; Eller, P. Gary (2006)."Curium"(PDF). In Morss; Edelstein, Norman M.; Fuger, Jean (eds.).The Chemistry of the Actinide and Transactinide Elements (3rd ed.). Dordrecht, The Netherlands:Springer Science+Business Media. p. 1401.ISBN978-1-4020-3555-5. Archived fromthe original(PDF) on 2010-07-17.
^Cunningham, B. B.; Wallmann, J. C. (1964). "Crystal structure and melting point of curium metal".Journal of Inorganic and Nuclear Chemistry.26 (2): 271.doi:10.1016/0022-1902(64)80069-5.OSTI4667421.
^Stevenson, J.; Peterson, J. (1979). "Preparation and structural studies of elemental curium-248 and the nitrides of curium-248 and berkelium-249".Journal of the Less Common Metals.66 (2): 201.doi:10.1016/0022-5088(79)90229-7.
^Gmelin Handbook of Inorganic Chemistry, System No. 71, Volume 7 a, transuranics, Part B 1, pp. 67–68.
^Eubanks, I.; Thompson, M. C. (1969). "Preparation of curium metal".Inorganic and Nuclear Chemistry Letters.5 (3): 187.doi:10.1016/0020-1650(69)80221-7.
^Noe, M.; Fuger, J. (1971). "Self-radiation effects on the lattice parameter of244CmO2".Inorganic and Nuclear Chemistry Letters.7 (5): 421.doi:10.1016/0020-1650(71)80177-0.
^Haug, H. (1967). "Curium sesquioxide Cm2O3".Journal of Inorganic and Nuclear Chemistry.29 (11): 2753.doi:10.1016/0022-1902(67)80014-9.
^Zaitsevskii, Andréi; Schwarz, W. H. Eugen (April 2014). "Structures and stability of AnO4 isomers, An = Pu, Am, and Cm: a relativistic density functional study".Physical Chemistry Chemical Physics.2014 (16):8997–9001.Bibcode:2014PCCP...16.8997Z.doi:10.1039/c4cp00235k.PMID24695756.
^Keenan, T. (1967). "Lattice constants of K7Cm6F31 trends in the 1:1 and 7:6 alkali metal-actinide(IV) series".Inorganic and Nuclear Chemistry Letters.3 (10): 391.doi:10.1016/0020-1650(67)80092-8.
^Burns, J.; Peterson, J. R.; Stevenson, J. N. (1975). "Crystallographic studies of some transuranic trihalides: 239PuCl3, 244CmBr3, 249BkBr3 and 249CfBr3".Journal of Inorganic and Nuclear Chemistry.37 (3): 743.doi:10.1016/0022-1902(75)80532-X.
^Wallmann, J.; Fuger, J.; Peterson, J. R.; Green, J. L. (1967). "Crystal structure and lattice parameters of curium trichloride".Journal of Inorganic and Nuclear Chemistry.29 (11): 2745.doi:10.1016/0022-1902(67)80013-7.S2CID97334114.
^Weigel, F.; Wishnevsky, V.; Hauske, H. (1977). "The vapor phase hydrolysis of PuCl3 and CmCl3: heats of formation of PuOC1 and CmOCl".Journal of the Less Common Metals.56 (1): 113.doi:10.1016/0022-5088(77)90224-7.
^Damien, D.; Charvillat, J. P.; Müller, W. (1975). "Preparation and lattice parameters of curium sulfides and selenides".Inorganic and Nuclear Chemistry Letters.11 (7–8): 451.doi:10.1016/0020-1650(75)80017-1.
^Girnt, Denise; Roesky, Peter W.; Geist, Andreas; Ruff, Christian M.; Panak, Petra J.; Denecke, Melissa A. (2010). "6-(3,5-Dimethyl-1H-pyrazol-1-yl)-2,2′-bipyridine as Ligand for Actinide(III)/Lanthanide(III) Separation".Inorganic Chemistry.49 (20):9627–9635.doi:10.1021/ic101309j.PMID20849125.S2CID978265.
^abGlorius, M.; Moll, H.; Bernhard, G. (2008). "Complexation of curium(III) with hydroxamic acids investigated by time-resolved laser-induced fluorescence spectroscopy".Polyhedron.27 (9–10): 2113.doi:10.1016/j.poly.2008.04.002.
^abHeller, Anne; Barkleit, Astrid; Bernhard, Gert; Ackermann, Jörg-Uwe (2009). "Complexation study of europium(III) and curium(III) with urea in aqueous solution investigated by time-resolved laser-induced fluorescence spectroscopy".Inorganica Chimica Acta.362 (4): 1215.doi:10.1016/j.ica.2008.06.016.
^abMoll, Henry; Johnsson, Anna; Schäfer, Mathias; Pedersen, Karsten; Budzikiewicz, Herbert; Bernhard, Gert (2007). "Curium(III) complexation with pyoverdins secreted by a groundwater strain of Pseudomonas fluorescens".BioMetals.21 (2):219–228.doi:10.1007/s10534-007-9111-x.PMID17653625.S2CID24565144.
^abMoll, Henry; Geipel, Gerhard; Bernhard, Gert (2005). "Complexation of curium(III) by adenosine 5′-triphosphate (ATP): A time-resolved laser-induced fluorescence spectroscopy (TRLFS) study".Inorganica Chimica Acta.358 (7): 2275.doi:10.1016/j.ica.2004.12.055.
^Moll, H.; Stumpf, T.; Merroun, M.; Rossberg, A.; Selenska-Pobell, S.; Bernhard, G. (2004). "Time-resolved laser fluorescence spectroscopy study on the interaction of curium(III) with Desulfovibrio äspöensis DSM 10631T".Environmental Science & Technology.38 (5):1455–1459.Bibcode:2004EnST...38.1455M.doi:10.1021/es0301166.PMID15046347.
^Seaborg, Glenn T. (1996). Adloff, J. P. (ed.).One Hundred Years after the Discovery of Radioactivity. Oldenbourg Wissenschaftsverlag. p. 82.ISBN978-3-486-64252-0.
^Rieder, R.; Wanke, H.; Economou, T. (September 1996). "An Alpha Proton X-Ray Spectrometer for Mars-96 and Mars Pathfinder".Bulletin of the American Astronomical Society.28: 1062.Bibcode:1996DPS....28.0221R.
^Hoffmann, K.Kann man Gold machen? Gauner, Gaukler und Gelehrte. Aus der Geschichte der chemischen Elemente (Can you make gold? Crooks, clowns and scholars. From the history of the chemical elements), Urania-Verlag, Leipzig, Jena, Berlin 1979, no ISBN, p. 233
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