Study of multiferroic properties of rare earth substituted xBa0.95Sr0.5TiO3-(1-x)BiFe0.9Re0.1O3 perovskite ceramics

Abstract

Various multiferroic xBa0.95Sr0.05TiO3-(1‒x)BiFe0.9Re0.1O3 [xBST-(1‒x)BFRO], (where, Re = Gd, Dy and Sm) ceramics were synthesized by the standard solid-state reaction technique. The crystalline phase, microstructure, dielectric properties, AC conductivity, impedance spectroscopy, M-H hysteresis loop, complex initial permeability and magnetoelectric (ME) coefficient of the compositions were investigated. The X-ray diffraction pattern indicated that xBST-(1‒x)BFRO ceramics showed a structural transition from rhombohedral to cubic phase. The average grain size was observed to be decreased with increasing BST content. The value of dielectric constant ( / ) was found increasing whereas dielectric loss decreasing significantly with increasing BST content. The xBa0.95Sr0.05TiO3- (1‒x)BiFe0.9Gd0.1O3 [xBST-(1‒x)BFGO] ceramics had higher value of  / than those of xBa0.95Sr0.05TiO3-(1‒x)BiFe0.9Dy0.1O3 [xBST-(1‒x)BFDO] and xBa0.95Sr0.05TiO3- (1‒x)BiFe0.9Sm0.1O3 [xBST-(1‒x)BFSO] ceramics. Temperature dependent dielectric properties showed a transition between 255 and 360; 225 and 355; 200 and 300 °C for xBST- (1‒x)BFGO, xBST-(1‒x)BFDO and xBST-(1‒x)BFSO ceramics, respectively. Temperature dependent AC conductivity measurements showed semiconducting behavior. Value of grain resistance was determined from impedance spectroscopy studies and it showed decreasing trend with increasing temperature which indicated the characteristics of the negative temperature coefficient of resistance. The maximum values of remnant magnetization determined from M-H hysteresis loops were found to be 0.080, 0.086 and 0.034 emu/g for xBST-(1‒x)BFGO, xBST-(1‒x)BFDO and xBST-(1‒x)BFSO ceramics, respectively. The enhanced magnetization was found due to the modification of crystal structure when BST was added in rare earth doped BiFeO3. The complex initial permeability was improved with increasing BST concentration because of reduced oxygen vacancies which helped to move the domain wall easily. An enhanced ME coupling was also observed in the studied samples and the highest values of ME coefficient were found 1.67, 1.20 and 0.66 mV.cm-1.Oe-1 for xBST-(1‒x)BFGO, xBST-(1‒x)BFDO and xBST-(1‒x)BFSO ceramics, respectively.