Conductibilité electrique aux basses températures des composés binaires Cr 2X 3 et Cr 3X 4 (X = S, Se ou Te)

Abstract

Electrical resistivity of some binary compounds Cr 2X 3 and Cr 3X 4 (X = S, Se or Te) is studied on polycrystalline samples with the four point probe method, at temperatures between 4.2 and about 330 K. A metallic behavior is observed on Cr 2Te 3, Cr 3Te 4, Cr 3S 4 and the 3 c′ form of Cr 2Se 3. Some other compounds are semiconductors: Cr 3Se 4 ( E 300K ≈ 0.07 eV; E 4.2K = 2.07 × 10 −4 eV), the 2 c′ form of Cr 2+εSe 3 ( E 300K ≈ 0.074 eV; E 4.2K = 2.76 × 10 −4 eV) and the 3 c′ form of Cr 2S 3 ( E 275K ≈ 0.55 eV). The observed results seem to be closely related to the nature of the octahedral neighborhood of the cations.