Enhancement of electrical and magnetic properties in acceptor-doped BaTiO3 ferroelectric ceramics
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BaTi1−xMnxO3 (x = 0.00, 0.25, 0.50, 0.75 mol%) (BTMO) ceramics were synthesized through sol–gel combustion method. The structural studies suggested that Mn-doped BaTiO3 (BTO) ceramics exhibit a tetragonal structure with P4mm space group via Rietveld refinement analysis. Also, the phonon mode at 308 cm−1 through Raman spectral analysis confirms the local structure of tetragonal symmetries. The redshift observed in UV-absorption spectra indicates a decrease of optical band gap from 3.13 to 2.71 eV with increasing Mn2+ doping. The observed decrease in the intensity of PL emission spectra was due to an increase of Mn2+ concentration. This indicates that a decrease in oxygen vacancies and a reduction in the number of electrons attributed to the Burstein–Moss shift. The carrier hopping process between Mn2+ and Mn3+ is responsible for dielectric as well as magnetization behavior. The ferroelectric double hysteresis loops are related to a ferroelectric and anti-ferroelectric order and it increases with the increase of Mn ion concentration in BTO. Through P–E measurements, the value of remnant electric polarization and coercive field found to be increased with Mn concentration in BTO samples. For BTO sample, two EPR signals with g = 1.969 and g = 2.000 singlets can be assigned with ionized Ba and Ti-vacancy defects. In addition, the EPR signal for BTMO shows a good correlation with Ti vacancies as compensating for lattice defects. Further, the Mn doping induced a weak ferromagnetic to ferromagnetic state due to free carrier concentrations.
The authors thankful to Department of Physics, NIT Tiruchirappalli for the multiferroic tester facility (MHRD, Government of India) for PE measurements.
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