Piezoelectric Property of a Tetragonal (Ba,Ca)(Zr,Ti)O3 Single Crystal and Its Fine-Domain Structure.

A tetragonal (Ba,Ca)(Zr,Ti)O3 (BCZT) single crystal was grown by a flux method, and the piezoelectric coefficient ( d33) was characterized. The piezoelectric response was proved to be associated with polarization extension, which was successfully used to explain the variation in d33*. From the intrinsic aspect, the compositional effect on Landau free-energy profiles was discussed, showing an "extender" nature of the as-grown crystal and the increasing tendency of structural instability toward the morphotropic phase boundary. From the extrinsic aspect, the evolution of domain structure under various external fields (electric and temperature) was studied, revealing that the fine-domain structure of the as-grown BCZT single crystal was stable to E-field and temperature. The results manifest possibilities of further improving the piezoelectric property of the BCZT single crystal, which requires optimization of the crystal growth technique in future work.