Probing diffusive phase transition in Ba(Ti0.80 Zr0.20)O3-0.5(Ba0.70 Ca0.30)TiO3 nanofibers by temperature-dependent piezoelectric force microscopy

Ba(Ti0.80Zr0.20)O-3-0.5(Ba0.70Ca0.30)TiO3 (BTZ-0.5BCT) nanofibers (NFs) demonstrated diffusive phase transition, resulting in an enhanced Curie temperature TC. 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 degrees C. The result shows that the first harmonic piezoresponse initially increased with temperatures, yet two singularities appeared at 120 and 180 degrees 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 TC of BTZ-0.5BCT nano-ceramics is around 180 degrees C, representing the TC 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. Copyright (C) EPLA, 2020