Piezoelectric properties and structural evolution in La- and Al-modified K0.5Bi0.5TiO3 ceramics

The present study reports the effects of La3+ and Al3+ substitution on the structural, dielectric, and piezo-electric properties of (1-x)(K0.5Bi0.5)TiO3-xLaAlO3 (named as KBT-LAO) (x = 0-0.03) ceramics. Rietveld re-finement of room temperature synchrotron X-ray diffraction (SXRD) data showed a decrement in tetragonal distortion and an increase in cubic symmetry with the increase in LAO content. An additional dielectric anomaly was noticed in poled x = 0.03 LAO sample. A diffuse dielectric curve with an improved relaxor behavior was observed in temperature-dependent dielectric measurements with LAO incorporation in KBT. The enhancement in activation energy values (from 0.95 +/- 0.01 eV to 1.24 +/- 0.01 eV) signified the sup-pression of oxygen vacancies with LAO doping. The current-voltage (I-V) plot suggested an improvement in room temperature DC resistivity in KBT-LAO solid solution. An increasing trend was noticed in the piezo-electric charge coefficient value and was found to be maximum (d33 -80 pC/N) for the 3 % LAO-doped sample. The improved piezoelectric voltage coefficient (g33 -24 x 10-3 V m/N) was observed for the x = 0.03 LAO doped sample, which is a 60 % improvement over the pure KBT sample (g33 -14 x 10-3 V m/N). Additionally, an energy harvesting experiment was performed on a piezo device prepared using poled 3 % LAO-doped ceramic. The peak-to-peak voltage & current of -0.420 V & -0.18 uA under normal finger tapping.(c) 2023 Elsevier B.V. All rights reserved.