Rutile type oxides prepared from Cr1−xFexOOH with InOOH type structure

Iron doped CrO₂ was prepared by thermal decomposition of Cr_1?xFe_xOOH with InOOH type structure which was synthesized under high temperature-pressure conditions. Charge compensation in the rutile type oxides was made by generating Cr⁵⁺ ion in the compositional range of x ≦ 0.1 and oxygen vacancy in the range of $\text{x}\text{≧ 0.15}$. The Curie temperature of rutile type oxide rose up to 162°C at x=0.1, then fell with increase of iron content. The lowest Curie temperature was 88°C at the initial composition of x=0.3. The region where the Curie temperature rises correspond to that where Cr⁵⁺ is produced, and the region where the Curie temperature drops to that where oxygen vacancy is generated.