Electrocaloric effect in Ba0.2Ca0.8Ti0.95Ge0.05O3 determined by a new pyroelectric method

The present letter explores the electrocaloric effect (ECE) in the lead-free oxide Ba0.8Ca0.2Ti0.95Ge0.05O3 ceramics (BCTG). The electrocaloric responsivity xi = (dT/dE) was determined by two different methods using the Maxwell relationship xi alpha (partial derivative P/partial derivative T)(E). In a first well-known indirect method, P-E hysteresis loops were measured in a wide temperature range from which the pyroelectric coefficient pE = (partial derivative P/partial derivative T)(E) and thus. were determined by derivation of P(T, E) data. In the second novel method the pyroelectric coefficient pE and consequently the electrocaloric responsivity. were determined by direct measurements of the pyroelectric currents under different applied electric fields. Within the experimental error, good agreement was obtained between two methods with xi = 0.18 +/- 0.05.10(-6) K.m.V-1 at about 410 K. Copyright (C) EPLA, 2015