Defect induced ferromagnetism in h-BaTiO3 synthesized from t-BaTiO3 by microwave heating

Abstract

Structure modification of tetragonal BaTiO3 (t-BaTiO3) and corresponding phase transition by microwave heating were investigated. The sample compound was heated by 1.8 kW power and 2.45 GHz frequency microwave irradiation under N-2 atmosphere in a short experimental duration of 14 min. The maximum temperature of the surface of the sample was 1115 degrees C. The structure of the microwave irradiated BaTiO3 was then analyzed by employing X-ray diffraction (XRD), Rietveld refinement analysis, Raman spectroscopy, and field emission scanning electron microscopy techniques. From XRD and Rietveld refinement analysis, the microwave irradiated BaTiO3 sample was composed of hexagonal 89%, cubic 5% and tetragonal 6%. Due to the direct internal heating mechanism of microwaves, the core temperature of the sample might be higher than the phase transition temperature. The magnetic behavior of the sample was investigated using a vibrating sample magnetometer. The results indicated that the microwave irradiated BaTiO3 exhibited mixed magnetism: ferromagnetic nature at low applied magnetic fields and diamagnetic nature at high applied magnetic fields. (C) 2017 Elsevier B.V. All rights reserved.