Adjustable negative electrocaloric effect in Pb1+xZrO3 thin films

• Published in: Journal of materials science. Materials in electronics 2021-07, Vol.32 (14), p.19446-19454
• Main Authors: Ye, Yi, Huang, Fengzhen, Lei, Lin, Liu, Lin, Yan, Shuo, Hu, Xueli, Yang, Wenjin, Lu, Xiaomei, Zhu, Jinsong
• Format: Article
• Language: English
• Subjects: Characterization and Evaluation of Materials; Chemistry and Materials Science; Cooling; Electric fields; Electronic devices; Ferroelectric materials; Ferroelectricity; Lead; Materials Science; Optical and Electronic Materials; Room temperature; Silicon dioxide; Silicon substrates; Thin films; Titanium
• ISSN: 0957-4522; 1573-482X
• DOI: 10.1007/s10854-021-06462-9

Electrocaloric effect (ECE) driven by electric field is suitable for implementation of built-in cooling in electronic devices. However, most of the known electrocaloric materials show low adiabatic temperature change (∆T) near room temperature and usually require high electric field. Here, the investigation of ECE in Pb 1+ x ZrO 3 ( x  = 0, 0.1, 0.15) thin films, which were prepared on Pt/Ti/SiO 2 /Si substrates by metal organic deposition method, reveals that both the magnitude and the appearance temperature range of ∆T can be controlled by Pb concentration. Decreased lead vacancies and enhanced interface layer are induced with the increase of Pb concentration. This can postpone the transition from AFEs to ferroelectrics of PbZrO 3 films under a given electric field ( E ) and thus control the temperature range of negative ECE. As a result, large isothermal entropy change (∆S) and ∆T are observed in the temperature range from 260 to 494 K, depending on the applied electric field and Pb concentration. Large ECE Δ T ∼ - 24.9 K , Δ T / Δ E ∼ 0.054 K cm/kV at room temperature (303 K) is obtained in Pb 1.1 ZrO 3 films under 460 kV/cm. This result provides a convenient method for modulating ECE of PbZrO 3 -based materials and will benefit its applications in cooling devices.