Tantaloxide durch Gasphasenhydrolyse, Druckhydrolyse und Transportreaktion aus 2H-TaS2: Synthesen von TT-Ta2O5 und T-Ta2O5 und Kristallstruktur von T-Ta2O5

✍ Scribed by Hummel, Hans-U. ;Fackler, Richard ;Remmert, Peter

• Publisher: Wiley (John Wiley & Sons)
• Year: 1992
• Tongue: English
• Weight: 585 KB
• Volume: 125
• Category: Article
• ISSN: 0009-2940
• DOI: 10.1002/cber.19921250304

✦ Synopsis

Tantalum Oxides by Gasphase Hydrolysis, Pressure Digestion, and Chemical Transport of 2H‐TaS~2~: Synthesis of TT‐Ta~2~O~5~, T‐Ta~2~O~5~ and X‐ray Structure Determination of T‐Ta~2~O~5~

TT‐Ta~2~O~5~ is obtained by pressure digestion in water using 2H‐TaS~2~ as starting material at a temperature of 200°C followed by a dehydratization procedure of initially formed amorphous HTaO~3~. The X‐ray powder diagram of TT‐Ta~2~O~5~ revealed a hexagonal unit cell with space group P6/mmm and lattice constants a = 3.639, c = 3.901 Å. This material undergoes a phase transition during heating from 20 to 900°C. The resulting product is crystallizing orthorhombic with space group __Pmm__2 and lattice constants a = 43.997(8), b = 3.894(1), c = 6.209(3) Å and Z = 12. Single crystals of this phase (T‐Ta~2~O~5~) have been prepared by chemical transport reaction using TT‐Ta~2~O~5~ as starting material and NH~4~Cl as transport agent. The structure of T‐Ta~2~O~5~ consists of pentagonal‐bipyramidal coordinated tantalum atoms connected with distorted TaO~6~ octahedra. The Ta–O distances vary between 1.84 and 3.09 Å and the mean Ta–O distance is 1.99 Å.