Enhanced electrocaloric effect in lead-free BaTi1−xSnxO3 ceramics near room temperature

Abstract

The electrocaloric effect in lead-free BaTi1−xSnxO3 (BTSn, x = 0.08, 0.105, and 0.14) ferroelectric ceramics was studied by using an indirect method. It was found that the largest electrocaloric response could be achieved in BTSn with x = xQP = 0.105 near room temperature with an adiabatic temperature change ΔT of 0.61 K and an electrocaloric strength ΔT/ΔE of 0.31 K mm kV−1, under a modest electric field ΔE of 20 kV cm−1, which is comparable with the best values reported in lead-free materials. These enhanced values are attributed to the multiphase (four phases) coexistence at x = xQP corresponding to the quasi-quadruple point composition.

Some strategies for improving caloric responses with ferroelectrics

“…17 Such electrocaloric effect can be further enhanced in thick film form. 45 The phase transition temperature where the maximum electrocaloric response occurs can be tailored by varying the doping level 16,17 without destroying the multiphase coexistence 45 or through solid solutions. 46 Such approach is therefore efficient for tuning the working temperature and improving electrocaloric responses of materials.…”

“…2 In addition to the use of first-order transition materials, other strategies to enhance the caloric properties are possible such as geometrical optimization, [10][11][12][13][14] maximizing the number of close-energy phases near a critical point in the temperature-composition phase diagram, [15][16][17] combining conventional and inverse caloric responses in a single refrigeration cycle, 18,19 introducing extra available degree of freedom like strain via mechanical stress, [20][21][22] and multicaloric effect driven by either single stimulus or multiple stimuli (applied/removed simultaneously or sequentially). 5 There are several excellent review articles and books treating on the electrocaloric effect through its history, related properties, and potential design for cooling applications.…”

Electrocaloric response near room temperature in Zr- and Sn-doped BaTiO 3 systems

“…In addition, the ECE was investigated in Sn-doped BaTiO 3 ceramics using the indirect method, e.g. deducing the ECE from the pyroelectric coefficient using the Maxwell relation [6,[10][11][12]. A significantly higher ECE was observed in samples with compositions at the ICP [10][11][12].…”

Electric-field-induced phase transition and electrocaloric effect in PMN-PT

“…However, T c in many ferroelectric materials is considerably higher than room temperature, which substantially limits their potential application in solid-state cooling devices. In the past decade, considerable efforts have been exerted to achieve high EC effects at room temperature, [13,[18][19][20][21][22][23][24][25][26] such as applying a stress field, [20,21,27] doping, [22] introducing defects, [18,23,27] using the tetragonal-cubic phase transition, [10,12] and taking advantage of the morphotropic phase boundary (MPB) region in solid solutions. [13,24,28] PMN-PT is a solid solution of the relaxor PMN and the ferroelectric PbTiO 3.…”