| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 1515786 | Journal of Physics and Chemistry of Solids | 2015 | 9 Pages |
•Niobium oxide and hydroxide were reduced by calcium dissolved in CaCl2 melt.•Sub-micrometer spherical metallic particles with coral-like morphology were obtained.•High capacitance (CV) because of small shrinkage during sintering.
Metallic niobium powder was produced for applications in electric capacitors via calciothermic reduction of niobium hydroxide in molten CaCl2. Sub-micrometer spherical metallic particles with coral-like morphologies reflected the particle size of the starting oxide powder. A fine powder was obtained from the mixtures of niobium hydroxide and CaO or Ca(OH)2, respectively.Sintered pellets of the metallic powder showed a higher capacitance (CV) than those of the simply reduced powder without pre-treatment, because the shrinkage during sintering was smaller. The CV was as large as that of commercially sintered pellets for tantalum capacitors. Therefore, this niobium powder would act as a higher-voltage capacitor by applying chemical anodic treatment at higher voltages, and lower oxygen content in the reduced power could realize a lower leak current.
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