Structure type of hexagonal tantalum bronzes with variable composition K6Ta6 + Z O15F6(F, O)y: Ta(5 − δ)+ bronzes and Ta5+ compounds

Abstract

-The structure type of hexagonal compounds with the variable composition K 6 Ta 6 + z O 15 F 6 ( F , O ) y , where Z ≤ 1 and y ≤ 3 (sp. gr. P 6/ m , a ~ 13.12 Å, c ~ 3.86 Å) has been studied. Based on the structural data for a crystal of the Ta 5+ -containing compound and two crystals of Ta (5 -δ )+ -containing bronzes formed at the cathode during electrolysis of salt melts containing Ta + cations, it was established that the bronze formation is associated with the interstitial defects of intercalated Ta cations. The scheme of reduction of Ta cations at the cathode is suggested, and the formulas of the compounds are obtained with due regard for partial Ta reduction to various integral oxidation degrees. The crystals of the colorless transparent Ta

Crystal Chemistry and Selected Physical Properties of Inorganic Fluorides and Oxide-Fluorides

“…Electrolysis of a melt of the K 2 TaOF 5 –(KF, NaF, LiF) eut. systems produces tantalum oxide fluoride bronzes . Transport occurs from a tantalum oxide anode to a molybdenum cathode.…”

“…systems produces tantalum oxide fluoride bronzes. 432 Transport occurs from a tantalum oxide anode to a molybdenum cathode. The crystals exhibit various compositions from colorless K 6 Ta 6.27 O 15 F 7.4 , to brown semitransparent K 6 Ta 6.88 O 15 F 8.2 , and to dark-gray metal-like K 6 Ta 7 O 15 F 7 .…”

Electrodeposition of Beta-Tantalum in Alkali Metal Halides and Oxohalide Melts

“…As can be seen from Table II, the electrodeposition of α-Ta and β-Ta in the LiCl melt is accompanied by formation of a phase isostructural to Ta 2 O 5 phase (50%). Codeposition with α-Ta and β-Ta of K 6−x Ta 10.8 O 30 tetragonal bronze 25 was detected in the NaCl-KCl melt and electrocrystallization of K 6 Ta 6.5 O 15+x F 6+y hexagonal bronze 26 was found in the KCl melt. The β-Ta with a low content of α-Ta was electrodeposited on a cathode in the RbCl melt.…”