Ermittlung der struktur des tantalsuboxydes TaO z (Ta 2O) mittels elektronenbeugung

Abstract

Thin monocrystalline films of tantalum, which were obtained by electropolishing, display superstructure diffraction diagrams when they are heated up to 300–450°C in an electron diffraction camera and then exposed to oxygen at 5 × 10 −4 Torr pressure. These diagrams correspond to the phase TaO z . Interpretation of the diagrams shows that the phase TaO z belongs to the cubic system ( a = 6.68 A ̊ ) and reveals the composition Ta 2O. Every four oxygen atoms surround tetrahedrally a tantalum atom, the distance between oxygen and tantalum being ( a 8 )√ 3, between the midpoints of two tetraheders ( a 2 )√3, respectively. The structure of Ta 2O is similar to that of the C 3-(Cu 2O)-type.