Investigations on the phase transition of Mn-doped BaTiO3 multifunctional ferroelectric ceramics through Raman, dielectric, and magnetic studies

摘要

BaTiO3 (BTO) and BaTi1-xMnxO3 (x=0.25, 0.50, 0.75mol%) ceramic materials have been prepared by the sol-gel combustion method. X-ray diffraction (XRD) has been carried out to characterize the phase purity and crystal structure of the prepared compounds, and all XRD patterns suggest tetragonal structure with the phase group of P4mm. The variation in the estimated lattice parameters confirms the incorporation of Mn atoms at Ti site of BTO. Raman spectroscopy studies under various temperatures suggest a phase transition from tetragonal to cubic phase at 433K, identified by a distinct Raman mode at 308cm(-1). As Raman modes are getting softened by Mn doping, phase transition temperature of the Mn-doped compounds is significantly decreased from 473K (x=0%) to 433K (x=0.75%). Dielectric properties such as permittivity and dielectric loss as the function of frequency under various temperatures have two distinct dielectric anomalies (i) at 393K associated to tetragonal to cubic phase transition and (ii) at 550K due to oxygen vacancy defect in the samples. Observation of weak ferromagnetism at 2, 300, and 400K in the M (H) and ZFC-FC curve, suppose its origin due to an intriguing exchange interaction between Mn and oxygen vacancies.