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.
