Structural, dielectric, and multiferroic properties of (Bi0.5K0.5)(Fe0.5Nb0.5)O-3

摘要

A polycrystalline sample of (Bi0.5K0.5)(Fe0.5Nb0.5)O-3 was prepared using a mixed oxide at 1000 degrees C. The preliminary structural analysis using X-ray diffraction data of the compound indicates the formation of a single-phase rhombohedral structure similar to that of parent BiFeO3. Microstructural and elemental analysis using a scanning electron micrograph and energy-dispersive X-ray spectroscopy, respectively, were carried out at room temperature with higher magnification exhibiting a uniform distribution of grains and stoichiometry. The appearance of hysteresis loops (P-E) confirms the existence of ferroelectricity of the sample with a high remnant polarization of (2P(r)) 17.76 mu Ccm(-2). Using impedance spectroscopy, the electrical properties of the material were investigated at a wide range of temperature (25-500 degrees C) and frequencies (1 kHz - 1 MHz) suggesting dielectric non-Debye-type relaxation in the material. The nature of the Nyquist plot (Z' similar to Z '') shows the dominance of the grain contribution in the impedance. The bulk resistance of the compound decreases with increasing temperature, like that of a semiconductor, which shows a negative temperature coefficient of resistance (NTCR) behavior. The frequency dependence of AC conductivity suggests that that the material obeys Jonscher's power law. Magnetic hysteresis (M-H) loop shows very weak ferromagnetic behavior at room temperature.ud