Ermittlung der Struktur des Tantalsuboxydes TaO y (Ta 32O 9) mittels Elektronenbeugung

Abstract

Thin monocrystalline films of tantalum, obtained by electropolishing, display superstructure diffraction diagrams when they are heated up to 300°C and then exposed to oxygen at 5 × 10 −4 Torr pressure. These diagrams correspond to the phase TaO y . Interpretation of the diagrams shows that the phase TaO y belongs to the cubic system ( a = 13.4 A ̊ corresponding to 4 a Ta) and possesses the composition Ta 32O 9. Eighteen oxygen atoms form in each case a dense group consisting of eight primitive cubes with edge length a 8 . The midpoints of the groups form a cubic body centered lattice with edge length a.