Thin pellets: Fast electrochemical preparation of capacitor tantalum powders
Thin pellets: Fast electrochemical preparation of capacitor tantalum powders
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DOI：
10.1021/cm0618648
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发表时间：
2007-01-23
影响因子：
8.6
通讯作者：
Chen, George Z.
中科院分区：
文献类型：
--
作者：
Wu, Tian;Jin, Xianbo;Chen, George Z.
采用循环伏安法和恒电位电解法研究了1123 K时固态Ta 2 O 5在CaCl 2熔盐中的电化学还原反应，并结合光谱、电镜和元素分析等手段进行了研究。在电还原过程中的初始步骤是电化学驱动的氧化物-Ca 2+相互作用，导致形成两种或更多种稳定的含钙化合物，可能是Ca0.5Ta2O5和CaTa 2 O 5。然后在完全金属化之前将这些化合物还原成TaO和/或δ-TaO。在相对于Ag/AgCl比-0.9V更负的电势下，可以通过直接电解Ta 2 O 5粉末的薄且多孔的颗粒（尺寸类似于300 nm的结节状颗粒的聚集体）来制备细钽粉末（类似于200 nm颗粒的结节状颗粒的聚集体）。电流效率和能耗令人满意，例如在-1.0V下分别达到接近78%和接近2.4kWh/kg-Ta。通过在3.1V的槽电压下电解10小时，可以将所生产的Ta粉末中的氧浓度降低到低至1200 ppm。电解钽粉的比电容达到40 k μ FV/g。
Electrochemical reduction of solid Ta2O5 to Ta metal in molten CaCl2 at 1123 K has been studied by cyclic voltammetry and potentiostatic electrolysis, together with spectroscopic, electron microscopic, and elemental analyses. The initial step in the electro-reduction process is the electrochemically driven oxide-Ca2+ interaction, leading to the formation of two or more stable calcium-containing compounds which are likely Ca0.5Ta2O5 and CaTa2O5. These compounds are then reduced to TaO and/or delta-TaO before full metallization. At potentials more negative than -0.9 V vs Ag/AgCl, fine tantalum powder (aggregates of nodular similar to 200 nm particles) can be prepared by direct electrolysis of thin and porous pellets of the Ta2O5 powder (aggregates of nodular particles of similar to 300 nm in size). The current efficiency and energy consumption are satisfactory, for example, achieving similar to 78% and similar to 2.4 kWh/kg-Ta at -1.0 V, respectively. The oxygen concentration in the produced Ta powder can be reduced to as low as 1200 ppm by electrolysis at a cell voltage of 3.1 V for 10 h. The specific capacitance of the electrolytic Ta powder reaches 40 k mu FV/g.