Characterization of electrocaloric properties by indirect estimation and direct measurement of temperature–electric field hysteresis loops

Abstract

The electrocaloric properties of Pb(Zr,Ti)O 3 (PZT)-based and Ba(Zr,Ti)O 3 ceramics and Pb(Mg,Nb)O 3 -PbTiO 3 (PMN-PT) crystals were investigated by the indirect estimation and direct measurement of temperature-electric field (T-E) hysteresis loops. The measured T-E loops showed a similar shape to strain-electric field (s-E) loops. The adiabatic temperature change ΔT due to electrocaloric effects was estimated from the polarization change of these samples. ΔTs of 0.48 and 0.66 K were estimated for the (Pb,La)(Zr,Ti)O 3 (PLZT)(9.1/65/35) ceramics and PMN-PT crystals under a field of 30 kV/cm, respectively. The measured temperature changes ΔTs in these samples upon the release of the electric field from 30 kV/cm to zero were 0.39 and 0.36 K, respectively.

Direct measurement of temperature change due to elastocaloric effect in poled piezoelectric ceramics attached to metal

“…The measurements were performed as described in previous reports. [23][24][25][26][27] When measuring the ferroelectric properties and electric field-induced strain of the piezoelectric ceramics themselves, a sample cut out from a diaphragm into a 2 mm square was used.…”

“…Measurements of the electrocaloric effects were performed as in previous reports. [23][24][25][26][27] To produce electrocaloric effects, an alternating electric field was applied to an electrode from an external power source, and temperature changes due to electrocaloric effect and electric field-induced strain were measured. To measure the elastocaloric effects, the piezoelectric diaphragm was sandwiched between plastic supports so that the section of the diaphragm circle was located 13 mm from the center of the diaphragm.…”

“…The fieldinduced longitudinal strain of the piezoelectric ceramic typically has a butterfly shape, and is similar to what was previously obtained with PZT. 23) Figure 4 depicts the vertical strain of the backside of the diaphragm when an electric field of 17.7 kV cm −1 was applied at 0.1 Hz. The electric field-induced strain curve showed a butterfly shape for the ceramic piezoelectric diaphragm, which was close to the ideal.…”

Electrocaloric Properties of (Pb,La)(Zr,Ti)O3 and BaTiO3 Ceramics

“…BaTiO 3 ceramics were sintered from the commercial powders (Toda Kogyo). The powders were fired at 1225-1275°C for PLZT ceramics at 1300-1400°C for BaTiO 3 ceramics, respectively [20][21][22].…”

“…Concerning direct measurement of temperatureelectric field (T-E) hysteresis loops, the reports have been limited. Detailed measurements of various measurements are required to clarify the insights of the ECE [4,18,19,20].…”