Effect of Ho3+ doping on the electric, dielectric, ferromagnetic properties and TC of BiFeO3 ceramics

Multiferroic Bi1-xHoxFeO3 (x=0, 0.05, 0.1, 0.15, 0.2) ceramics have been prepared by rapid liquid phase sintering method. The effect of Ho doping on the structure, electrical, dielectric, ferromagnetism properties and T-C of BiFeO3 ceramics is studied. The result shows that all the peaks for Bi1-xHoxFeO3 samples can be indexed according to the crystal structure of pure BiFeO3 by XRD. When x=0.15 and 0.2, the samples consist of two phases including rhombohedral and orthorhombic. Ho doping BiFeO3 enhanced the electrical properties with lower leakage current density. This dielectric behavior of Bi1-xHoxFeO3 ceramics varies with content x and frequency, which might be understood in terms of oxygen vacancy, the displacement of Fe3+ ions and lattice phase transition. The magnetic moment of Bi1-xHoxFeO3 ceramics varies with temperature from 300 to 1000 K at 5 kOe. It shows that the T-N of BiFeO3 changes slightly from 638 K to 632 K with Ho3+ doping. The magnetic Curie temperature of Bi1-xHoxFeO3 will reduce from 970 K to 890 K with increasing Ho3+ content, depending mainly on the Fe-O-Fe super-exchange and magnetic structure of relative stability. By measuring the magnetic hysteresis loops, all the samples exhibit weak ferromagnetic behavior under 890 K and paramagnetism above 890 K. It evidences that the ferromagnetic phase transition of Bi1-xHoxFeO3 samples occurs at 890 K. (C) 2013 Published by Elsevier Ltd and Techna Group S.r.l.