The chemical and physical properties of CrO2and tetravalent chromium oxide derivatives

Abstract

The oxide of chromium (IV), Cr0₂, is a highly interesting compound for materials investigation in that it is ferromagnetic at room temperature and a good electrical conductor. The Curie temperature is 118°C, and the material can readily be demagnetized with little energy input. The electrical conductivity of this black compound is quite high for an oxide; it even rivals some of the metal conductors such as Mn and Gd at roomtemperature. Thls review describes procedures for preparing Cr0₂, presents its chemical and physical properties including the modifications observed with metal-ion substitutions, and discusses the reactions of Cr0₂ with other metal oxides together with the physical properties of the ternary products containing tetravalent chromium.