Electrocaloric effect in Ba(0.2)Ca(0.8)Ti(0.95)Ge(0.05)O(3) determined by a new pyroelectric method

TL;DR

This study introduces a new pyroelectric method to accurately measure the electrocaloric effect in lead-free Ba0.8Ca0.2Ti0.95Ge0.05O3 ceramics, demonstrating good agreement with traditional methods and identifying a significant electrocaloric responsivity near 410 K.

Contribution

A novel direct measurement technique for the electrocaloric effect in lead-free ceramics, validated against established indirect methods.

Findings

Electrocaloric responsivity of 0.18 +/- 0.05 x 10^-6 K.m.V^-1 at 410 K.

Good agreement between the new direct method and traditional indirect measurements.

Potential for improved characterization of electrocaloric materials.

Abstract

The present letter explores the electrocaloric effect (ECE) in the lead free oxide Ba0.8Ca0.2Ti0.95Ge0.05O3 ceramics (BCTG). The electrocaloric responsivity (dT/dE) was determined by two different methods using the Maxwell relationship (dT/dE)~(dP/dT)_E. In a first well-known indirect method, P-E hysteresis loops were measured in a wide temperature range from which the pyroelectric coefficient p_E=(dP/dT)_E and thus (dT/dE) were determined by derivation of P(T,E) data. In the second novel method the pyroelectric coefficient p_E and consequently the electrocaloric responsivity was 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 an electrocaloric responsivity equal to 0.18 +/- 0.05 10-6 K.m.V-1 was obtained at about 410 K