Correlation between charge states and enhanced properties in Ti-substituted and Ti, Sr co-substituted Y(Mn0.8Fe0.2)O3 ceramics

Y(Mn0.8Fe0.2)1-xTixO3 (x = 0.05 and 0.1) and 0.98Y(Mn0.8Fe0.2)O3-0.02SrTiO3 ceramics with hexagonal structure were prepared, and the microstructure, magnetic, dielectric and electrical characteristics combined with the charge states of magnetic ions were evaluated. Ti single-substitution did not cause the microcrack formation in the Y(Mn0.8Fe0.2)O3 ceramics. However, spontaneous microcracking took place in the Ti, Sr co-substitution ceramics. All the ion-substituted ceramics were predominantly antiferromagnetic with weak ferromagnetic properties at low temperature. The antiferromagnetic transition temperature was decreased upon Ti substitution whereas the magnetic ordering temperature was increased upon Ti, Sr co-substitution. The varied valence distributions of the Fe and Mn ions contributed to the modified magnetic properties. By Ti substitution, the dielectric loss and conductivity of the ceramics were obviously reduced, and this should be related to the decreased Mn2+ and Fe2+ contents in the mixed valence structure.