Crystal structure refinement, ferroelectric and ferromagnetic properties of Ho3+ modified BiFeO3 multiferroic material

Abstract

Multiferroic Bi1-xHoxFeO3 (x = 0, 0.05, 0.1) ceramics have been prepared by rapid liquid phase sintering method. The effect of Ho3+ doping on the crystal structure, dielectric, ferroelectric properties, TN and TM 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 and the grain size from 1 to 5 μm is observed for BiFeO3 samples with Ho3+ doped. The dielectric behavior of Bi1-xHoxFeO3 ceramics varies with frequency and temperature, which might be understood in terms of an oxygen vacancy, the displacement of Fe3+ ions and lattice phase transition. There is a perfect dielectric hysteresis phenomenon in the ɛr-V curves of Bi1-xHoxFeO3 samples at bias voltage with 10 V. Under the action of the bias voltage, more and more dipoles are“frozen”in the bias voltage direction and quit polarization gradually, resulting in lower dielectric constant. The unsaturated P-E hysteresis loop of Bi1-xHoxFeO3 (x = 0.05, 0.1) samples is obtained with a large 2Pr of 3.08 μC/cm2. The Pr, Mr of Bi0.9Ho0.1FeO3 sample is nearly 23, 35 times as large as that of BiFeO3, respectively. It can be inferred that Ho3+ doping in BiFeO3 ceramics is proved to be an effective way to modulate the ferroelectric and the magnetic properties. It shows that the TN of BiFeO3 changes slightly from 644 K to 638 K and the TM of Bi1-xHoxFeO3 will reduce from 878 K to 860 K with increasing Ho3+ content. It can be attributed to the Fe3+–O2+–Fe3+ super-exchange strength and the relative stability of the magnetic structure.