IMF2017

The electrocaloric effect (ECE) in ferroelectric and anti-ferroelectric materials is gaining great attraction in several fields of research due to its potential application in replacing the environmentally harmful conventional refrigeration by realizing solid-state cooling with compact size and high efficiency, which are highly desirable for a broad range of applications. In this work keeping three facts (environmentally friendly material, ECE near room temperature and better entropy change) we have prepared modified BaTiO₃. The samples are prepared by sol-gel synthesis followed by calcination at 800 ^οC and sintering at 1350 ^οC. Phase confirmation is done by X-ray diffraction. Scanning electron microscopy is carried out for microstructure and morphological analysis. Dielectric measurements are done at different temperatures up to 250 ^οC for a frequency range of 100 Hz to 10 MHz. The piezoelectric constant (d₃₃) is measured at room temperature. The piezo voltage constant (g₃₃) is derived from d₃₃ and relative dielectric constant ε₃₃. The Cuire temperature (T_C) is found to be decreased with increasing La concentration, and this is satisfactory with the aim. The ECE is calculated around the T_C by following the indirect method in which hysteresis loops are measured at different temperature and change in entropy is calculated using thermo-dynamical relations including Maxwell’s relation. The observed change in ECE for these modified BaTiO₃ is found to have a good correlation with the amount of La doping. The recoverable energy storage density calculated from the hysteresis loops also shows the similar correlation with La-doping concentration.