Modified Ferromagnetic Chromium Dioxide

Several mixtures in the system Te-CrO2 were prepared by the decomposition of anhydrous chromic acid, CrO3, and telluric acid (H6TeO6) under high oxygen pressures; the physical and chemical properties were then studied. When Te was added, the grain size of CrO2 decreased rapidly from 5 to 10μ to 0.1 to 1.0μ and the magnetic coercive force increased from 20 to 120 oersteds. The magnetic Curie temperature and the lattice constants of CrO2 did not vary, however, with additions of Te up to 20 atomic %. X-ray analysis showed that the CrO2 plus Te was not a solid solution but a mixture of CrO2 and TeCr2O6 that was nonmagnetic.