Significant increase of Curie temperature and large piezoelectric coefficient in Ba(Ti_(0.80)Zr_(0.20))O_3-0.5(Ba_(0.70)Ca_(0.30))TiO_3 nanofibers

摘要

Ba(Ti_(0.80)Zr_(0.20))O_3-0.5(Ba_(0.7)Ca_(0.3))TiO_3 (abbreviated as BTZ-0.5BCT) is a piezoelectric ceramic with a high piezoelectric coefficient d_(33) (～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 ℃) 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 ℃. This means that the T_C of the NFs is nearly 207 ℃ 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.