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

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 N2 atmosphere in a short experimental duration of 14 min. The maximum te...

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Bibliographic Details
Published in:Journal of alloys and compounds 2017-07, Vol.712, p.627-632
Main Authors: Rajavaram, Ramaraghavulu, Park, Junwoo, Lee, Joonho
Format: Article
Language:English
Subjects:
Barium titanates
BaTiO3
Diamagnetism
Emission analysis
Ferromagnetism
Magnetic fields
Magnetic properties
Microwave heating
Microwave processing
Microwaves
Phase transitions
Raman spectroscopy
Rietveld refinement
Studies
Transition temperature
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Summary: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 N2 atmosphere in a short experimental duration of 14 min. The maximum temperature of the surface of the sample was 1115 °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. [Display omitted] •Synthesis of hexagonal BaTiO3 by microwave irradiation at low temperatures.•Heating of BaTiO3 by microwave irradiation was significant above ∼830 °C.•Structure of the prepared samples were investigated by XRD, rietveld refinement and Raman spectra analysis.•VSM analysis has revealed a mixed magnetic behaviours of ferromagnetism and diamagnetism at low and high magnetic fields.
ISSN:0925-8388
1873-4669
DOI:10.1016/j.jallcom.2017.04.150