Lattice strain driven dielectric insulation response of Sr1−xCa_xBi₂Nb₂O₉ ceramics

Abstract

In this paper, effects of lattice strain on dielectric properties of Sr 1Àx Ca x Bi 2 Nb 2 O 9 (x ¼ 0:0-0.5 in steps of 0.1) ceramics are reported. High frequency dipolar polarization is observed to increase for 10% calcium addition and suppresses thereafter on higher calcium concentrations. The dielectric loss values for all doped samples were lower compared to undoped one at frequencies beyond 1 kHz. The sample with x ¼ 0:1 shows room temperature dielectric constant in the range (130 AE 12) over a wide frequency range from 50 Hz to 1 MHz also minimum dielectric loss among all other sample for the same frequeny range. Remarkable increase in Curie temperature (T c ) by 50 C is recorded in the present work by increasing 10% calcium content in SBN compostion. All higher doped samples indicate increase in T c by further higher amount. In addition, dc conductivity of all samples is measured for all samples and increase in calcium content is observed to generate more insulating compositions compared to undoped SBN with higher intrinsic activation energies.

Influence of calcium doping on microstructure, dielectric and electric properties of BaBi2Nb2O9 ceramics

“…Since the calcium-oxygen bond is probably weaker the loss of bismuth oxide is expected to increase with increase in the calcium content. Such scenario implies a large number of negative charge carriers connected with the unsaturated oxygen ions [21]. The assumption opened the way to the following investigations, in particular the detailed impedance spectroscopy.…”