Characterization of Neodymium Calcium Oxyborate Piezoelectric Crystal with Monoclinic Phase

Abstract

Piezoelectric crystals of neodymium calcium oxyborate, NdCa4O(BO3)3 (NdCOB), were grown by the Czochralski technique. The density was measured using the Archimedes method and found to be 3.63 g/cm3, in good agreement with the theoretical value. The thermal properties of NdCOB have been investigated, with the specific heat being on the order of 0.550 J/(g °C). The four thermal expansion coefficients were measured and found to be α11 = 8.12, α13 = 0.680, α22 = 5.96, and α33 = 10.3 (10−6/°C), respectively. The relative dielectric permittivities were determined to be e11T/e0 = 9.90, e22T/e0 = 15.5, e33T/e0 = 10.2, and e13T/e0 = −1.60, respectively, with corresponding low dielectric loss at 100 kHz, being on the order of <0.1%. The complete set of dielectric, elastic, and piezoelectric constants for NdCOB single crystals were determined by the resonance method and compared to other oxyborate crystals ReCa4O(BO3)3 (Re = rare earth), where NdCOB exhibited relatively higher piezoelectric properties with d13 = −4....