Darstellung,Struktur und thermisches Verhalten einer neuen hexagonalen Ge-W-Bronze

Preparation, Structure, and Thermal Behaviour of a New Ge? W Bronce A hexagonal Ge-tungsten bronce with the composition Ge_0.24 WO₃ is obtained by chemical vapour deposition of a mixture of GeO₂ and WO₂(temperature gradient: 930 to 830°C). By means of an X-ray crystal structure analysis the space group was determined to be P622 and the lattice constants a = 744.0 pm, c = 381.7 pm. In absence of oxygen Ge_0.24 WO₃ is stable up to 850°C; in contact with air it is oxydized at temperatures T > 670°C. An anomaly in the thermal lattice expansion at temperatures T > 260°C is discussed.