| 초록 |
Electrocaloric effect (ECE) has been of a recent interest to the ferroelectric community as a promising solid-state cooling technique. Originally, the name, ECE, refers to the enthalpy change during a reversible electric-field-induced order and disorder phase transition, representatively, between ferroelectric and paraelectric phase. The presence of this effect was first reported in a BaTiO3 single crystal by Merz [Phys. Rev. 91, 513 (1953)]. However, not much attention was paid to the effect for any potential application, because the magnitude of the effect was determined to be too small at no more than 1.0 K. It was not until an ECE involving ΔT of about 12 K was reported by Mischenko et al. [Science 311, 1270 (2006)] that attention has been drawn to the topic with respect not just to theoretical interests but also to potentially available cooling technology alternative to the widely adopted gas-based one. Nevertheless, there always exist controversies over any reported cooling power such as 12 K by Mischenko et al.’s due to such high level of complexity in monitoring temperature change directly and undefined entropic contribution from structural variations. As an effort to quantify the correlation between ECE and the degree of entropy change, we prepared Pb(Sc1/2Ta1/2)O3 (PST) ceramic, where one can intentionally adjust the degree of disorderliness. For samples with a different degree of disorderliness, we determined ΔT directly using infrared camera. In this presentation, we will discuss the correlation between ECE and the degree of disorderliness quantitatively. |
