Absence of magnetism in Cr-doped In2O3: a case study of phase separation versus phase formation

Bulk ceramic Cr-doped In2O3 have been prepared using a solid-state reaction method at two different annealing temperatures. Room-temperature ferromagnetic behaviour is observed for all the compositions prepared at relatively low temperature. But from the Raman study the ferromagnetic oxide phase of CrO2 was identified. On the other hand, samples prepared at relatively high temperature show no detectable secondary phases as confirmed by x-ray diffraction and Raman study, but also no ferromagnetism. With increase in Cr content the paramagnetism state is merely enhanced. This is a strong indication that reports of ferromagnetism in Cr : In2O3 are due to a second phase, probably CrO2.