Antônio O. de Souzaa, Flávio F. Ivashitaa, Valdecir Biondoa, Andrea Paesano Jr.a, , , Dante H. Moscab

Journal of Alloys and Compounds

Zr1-xFexO2 samples were synthesized by a freeze-drying process, varying the iron concentration from x = 0 to x = 0.40. The solid solutions prepared were structurally and magnetically characterized. The results showed that the samples crystallized with the tetragonal structure of zirconia for low iron concentrations, with the respective cubic structure for intermediate iron concentrations, and that hematite is formed secondarily at the highest doping levels. It was also revealed that the lattice parameter of the zirconia solid solutions decreases almost linearly with increasing dopant concentration. All the monophasic samples are paramagnetic at room and low temperatures, except for the x = 0.25 sample, which revealed an incipient magnetization at 13 K. The fluctuations are antiferromagnetic throughout the temperature range and the exchange interaction was attributed to two mechanisms occurring simultaneously: a direct exchange interaction between nearest neighbors magnetic moments, dominant at the lowest temperatures and an indirect exchange interaction, induced by charge carriers, more effective at the highest temperatures. Both mechanisms are more active for higher iron concentrations.

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