Probing diffusive phase transition in Ba(Ti_0.80 Zr_0.20)O₃-0.5(Ba_0.70 Ca_0.30)TiO₃ nanofibers by temperature-dependent piezoelectric force microscopy

¹ Key Laboratory of Low Dimensional Materials and Application Technology of Ministry of Education, and School of Materials Science and Engineering - Xiangtan University, Xiangtan, Hunan 411105, China
² Shenzhen Key Laboratory of Nanobiomechanics, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences - Shenzhen, Guangdong 518055, China

^(b) bi.fu@siat.ac.cn
^(c) gk.zhong@siat.ac.cn
^(d) shxie@xtu.edu.cn

Received: 29 September 2019
Accepted: 26 November 2019

Abstract

Ba(Ti_0.80 Zr_0.20)O₃-0.5(Ba_0.70 Ca_0.30)TiO₃ (BTZ-0.5BCT) nanofibers (NFs) demonstrated diffusive phase transition, resulting in an enhanced Curie temperature T_C. As a result, it is scientific significant to probe the variation of ferro/piezoelectricity during such diffusive phase transition region. In this letter, the ferro/piezoelectricity of BTZ-0.5BCT NF was probed by piezoelectric force microscopy (PFM) under a series of temperatures revealing the piezoresponse of BTZ-0.5BCT NF increased with temperatures as the temperature is less than 180°C. The result shows that the first harmonic piezoresponse initially increased with temperatures, yet two singularities appeared at 120 and 180°C, and subsequently rapidly decreased to less than room temperature, demonstrating the corresponding ferroelectric transition process was a diffusive phase transition. Such a diffusive phase transition is caused by the discontinuous internal nanostructure of the NF and the size effect of ferro/piezoelectricity originated from the nano-ceramics. More importantly, the principal ferroelectric phase transition of nano-ceramics during such diffusive phase transition region was further quantified by principal component analysis (PCA) study. This indicates that the principal T_C of BTZ-0.5BCT nano-ceramics is around 180°C, representing the T_C of the whole BTZ-0.5BCT NF. Such a vivid description of the variated ferro/piezoelectricity with temperatures allows to provide a scientific method to quantify diffusive phase transition by PCA study.