Bipolar electro-caloric effect in Sr_xBa_(1−x)Nb₂O₆ lead-free ferroelectric single crystal

¹ Crystal Growth Laboratory, Laser Materials Development and Devices Division, Raja Ramanna Centre for Advanced Technology - Indore 452 013, India
² XS&CGS, CMPD, MSG, Indira Gandhi Centre for Atomic Research - Kalpakkam 603 102 India
³ Polar Domain Engineering Group, National Institute for Materials Science - Namiki, Tsukuba, Ibaraki, 305-0044, Japan

^(a) neel@rrcat.gov.in

Received: 21 July 2014
Accepted: 23 July 2014

Abstract

Here we report the anomalous electro-caloric effect (ECE) observed in lead-free Sr_xBa_(1−x)Nb₂O₆ (, 0.61 and 0.75) ferroelectric single crystals. Temperature-dependent hysteresis measurement revealed that the spontaneous polarization of Sr_xBa_(1−x)Nb₂O₆ single crystals with all the compositions under investigation decreases with a decrease in the temperature below the temperature of the dielectric maxima . As a consequence, these crystals exhibited negative electro-caloric effect at lower temperature along with the usual positive ECE above . The EC coefficient obtained near is 0.21, 0.43 and 0.28 K mm/kV for , 0.61 and 0.75 samples, respectively. The maximum values of in the negative ECE region are −1.4, −0.81 and for 50SBN, 61SBN and 75SBN, respectively.