The coexisting negative and positive electrocaloric effect in (Pb0.97La0.02)(Zr, Sn, Ti)O3 antiferroelectric thick films optimized via phase transition procedure
Pb0.97La0.02(Zr1 − x−ySnxTiy)O3 (PLZST, x = 0.37, 0.25 and 0.05; corresponding y = 0.08, 0.05 and 0.03) anti-ferroelectric (AFE) thick films with different phase structure were prepared by a sol–gel method. It is found that the PLZST thick films possess coexistence of the negative and positive electrocaloric effect (ECE). The negative ECE is caused by the transition from AFE to ferroelectric phase (FE) and enhanced as the AFE–FE switching field increases. The PLZST thick films for x = 0.37, 0.25 and 0.05 have the maximum negative temperature change ΔT of − 1.0, − 2.0 and − 4.1 °C near room temperature, respectively. Moreover, the maximum positive temperature change ΔT is 1.0, 5.4 and 6.1 °C near the Curie temperature in PLZST thick films (x = 0.37, 0.25 and 0.05), respectively, which is associated with the transition from induced FE to paraelectric state. The results indicate that the coexisting negative and positive ECE could be optimized by properly controlling the phase switching properties of AFEs.
The authors would like to acknowledge the financial support by the National Natural Science Foundation of China (51462027), the Ministry of Sciences and Technology of China through 973-Project (2014CB660811), the Program for Innovative Research Team in Universities of Inner Mongolia Autonomous Region (NMGIRT-A1605), the Natural Science Foundation of Inner Mongolia (2015JQ04, 2016MS0208, 2017MS0541), the Research Fund for Higher Education of Inner Mongolia (NJZY16161), the Grassland Talent Plan of Inner Mongolia Autonomous Region and the Innovation Fund of Inner Mongolia University of Science and Technology (2014QNGG01), the Innovation Guide Fund for Science and Technology of Inner Mongolia Autonomous Region (KCBJ2018034).