Enhanced electrocaloric effect at room temperature in Mn2+ doped lead-free (BaSr)TiO3 ceramics via a direct measurement

Xiang Niu,Tao Tao,Wei Liang,Sheng-Guo Lu,Bo Liang,Xianyi Chen,Haoxuan Li,Xiaodong Jian,Yingbang Yao

doi:10.1007/s40145-020-0450-1

Abstract

(Ba1−xSrx)(MnyTi1−y)O3 (BSMT) ceramics with x = 35, 40 mol% and y = 0, 0.1, 0.2, 0.3, 0.4, 0.5 mol% were prepared using a conventional solid-state reaction approach. The dielectric and ferroelectric properties were characterized using impedance analysis and polarization-electric field (P–E) hysteresis loop measurements, respectively. The adiabatic temperature drop was directly measured using a thermocouple when the applied electric field was removed. The results indicate that high permittivity and low dielectric losses were obtained by doping 0.1–0.4 mol% of manganese ions in (BaSr)TiO3 (BST) specimens. A maximum electrocaloric effect (ECE) of 2.75 K in temperature change with electrocaloric strength of 0.55 K·(MV/m)−1 was directly obtained at ∼21 °C and 50 kV/cm in Ba0.6Sr0.4Mn0.001Ti0.999O3 sample, offering a promising ECE material for practical refrigeration devices working at room temperature.

Highlights

With the fast increasing numbers of transistors in modern integrated circuits entry, thermal accumulation has become one of the crucial factors for chip damage, which causes the high electrical consumption, and the thermal impact on the stability of the electronic components [1,2]
Much effort has been devoted to electrocaloric effect (ECE) recently since the giant ECE responses have been reported for Pb(ZrTi)O3 thin films in 2006 [7] and poly(vinylidene fluoride-trifluoroethylene) [P(VDF–TrFE)] copolymers and poly(vinylidene fluoride–trifluoroethylene–chlorofluoroethylene) [P(VDF–TrFE–CFE)] terpolymers in 2008 [8]
X-ray diffraction (XRD) patterns procured at room temperature for BSMT ceramics with x = 35, 40 mol% and y = 0, 0.1, 0.2, 0.3, 0.4, 0.5 mol% are presented in Figs. 1(a) and 1(b), which show that a pure perovskite structure without any impurity peaks detected, meaning no secondary phases are introduced by the incorporation of manganese ions in the (BaSr)TiO3 (BST) ceramics

Summary

Introduction

With the fast increasing numbers of transistors in modern integrated circuits entry, thermal accumulation has become one of the crucial factors for chip damage, which causes the high electrical consumption, and the thermal impact on the stability of the electronic components [1,2]. Compared with two options above, bulk ceramics, e.g., in 2011, Rožič et al [10] reported a large ΔT ≈ 2 K for PLZT (8/65/35 mol%) bulk ceramics at ~410 K, and a ΔT > 2.5 K for 0.7Pb(Mg1/3Nb2/3)O3–0.3PbTiO3 (PMN–0.3PT) bulk ceramics at ~410 K with 88 and 90 kV/cm of external fields, respectively, and other numerous ferroelectric bulk materials with good electrocaloric properties have been reported [11,12,13] Taking both the environmental friendliness characteristic and large ECE response into consideration, lead-free BaTiO3 (BTO)-based ferroelectric ceramics with a perovskite structure is a promising ECE candidate, due to their first-order phase transition as well. Since the oxygen vacancies are attracted by the Mn2+ ions, the movable oxygen vacancies will be greatly mitigated, the loss tangent will be declined [25]

Experimental

Results and discussion

Conclusions