Significant increase of Curie temperature and large piezoelectric coefficient in Ba(Ti0.80Zr0.20)O3-0.5(Ba0.70Ca0.30)TiO3 nanofibers

Ba(Ti0.80Zr0.20)O-3-0.5(Ba0.7Ca0.3)TiO3 (abbreviated as BTZ-0.5BCT) is a piezoelectric ceramic with a high piezoelectric coefficient d(33) (similar to 620 pC N-1) and has been regarded as one of the most promising candidates to replace PZT-based materials (200-710 pC N-1). However, its Curie temperature T-C is relatively low (93 degrees C) limiting its application. In this letter, we found a temperature dependent Raman spectrum in BTZ-0.5BCT nanofibers (NFs), demonstrating a diffused tetragonal-to-cubic phase transition at 300 degrees C. This means that the T-C of the NFs is nearly 207 degrees C higher than that of the normal bulk material. The increased T-C is considered to be associated with the size effect of BTZ-0.5BCT nanoceramic subunits and the nanoporous nature of the fiber, resulting in discontinuous physical properties. The variation of the ferro/piezoelectricity over the fiber surface is attributed to the polycrystalline structure. The d(33) (173.32 pm V-1) is improved in terms of the decreased Q factor result in an increase in d(33) of 236.54 pm V-1 after polarization. With a high T-C and a very large d(33), BTZ-0.5BCT NFs are capable of providing electromechanical behavior used in moderate temperatures. (C) 2015 AIP Publishing LLC.