摘要
Electrocaloric effect （ECE） is much promising to realize high efficiency and environment friendly solution in solid cooling devices. Relaxor ferroelectrics are good candidates for the materials with high elec-trocaloric cooling power. In this paper, relaxor ferroelectric Ba（ZrxTil_x）O3 （BZT, x = 0.2, 0.21, 0.22, 0.23） ceramics were prepared with their temperature change （AT） induced by the ECE and electrocaloric strength （AT/E） measured within broad temperature range. It is found that the BZT21 （x = 0.21) exhibits the largest ATof-4.67 K and a high AT/E value of-0.46 km/MV at 9.9 MV/m and 25℃. BZT21 also exhi-bits apparent relaxor ferroelectric response, showing a very broad EC peak in the temperature interval between 15℃ and 50℃. Moreover, the relationship between EC properties and relaxor features was analyzed by piezoresponse force microscopy test. The results reveal that more dispersed phase structures induce additional configurational entropy, which is in favor for the enhanced EC performance. The inter-play and compromise between the kinetic and thermodynamic mechanisms of domain switching deter-mines the optimal composition for the EC performances of the BZT ceramics.
Electrocaloric effect(ECE) is much promising to realize high efficiency and environment friendly solution in solid cooling devices. Relaxor ferroelectrics are good candidates for the materials with high electrocaloric cooling power. In this paper, relaxor ferroelectric Ba(Zr_xTi_(1–x))O_3(BZT, x = 0.2, 0.21, 0.22, 0.23)ceramics were prepared with their temperature change(DT) induced by the ECE and electrocaloric strength(DT/E) measured within broad temperature range. It is found that the BZT21(x = 0.21) exhibits the largest DT of $4.67 K and a high DT/E value of $0.46 km/MV at 9.9 MV/m and 25 °C. BZT21 also exhibits apparent relaxor ferroelectric response, showing a very broad EC peak in the temperature interval between 15 °C and 50 °C. Moreover, the relationship between EC properties and relaxor features was analyzed by piezoresponse force microscopy test. The results reveal that more dispersed phase structures induce additional configurational entropy, which is in favor for the enhanced EC performance. The interplay and compromise between the kinetic and thermodynamic mechanisms of domain switching determines the optimal composition for the EC performances of the BZT ceramics.
基金
supported by the National Natural Science Foundation of China (51625202,51532003,and 51572141)
the National Basic Research Program of China (2015CB654603)
National Key Research & Development Program of China (2017YFB0701603)
