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 TC 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 TN 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.