Temperature dependent behaviors of electro-elastic properties of NdCa4O(BO3)3 crystal with monoclinic symmetry

Abstract

Rare-earth calcium oxyborate crystals (RECa4O(BO3)3, RECOB, RE: rare-earth elements) are a kind of multifunctional crystal materials. In this work, the temperature dependent behaviors of the electro-elastic constants of NdCOB crystal were investigated over the temperature range of –80–200 ℃, and their temperature coefficients were evaluated. It is found that NdCOB crystal possesses minimal variation of relative dielectric permittivities (<3%). The temperature coefficient of frequency for ZY cut with width shear vibration mode is in the order of 0.07 × 10−4/℃. The temperature coefficients of the elastic compliances are obtained to be in the range of −33.0 × 10−4/℃–32.2 × 10−4/℃. Particularly, the s44 and s66 were found to show low temperature coefficients of the elastic compliances, i.e. 1.0 × 10−4/℃ and −0.4 × 10−4/℃, respectively, indicating the existence of zero temperature coefficient of frequency crystal cut. Furthermore, the electromechanical coupling factors and piezoelectric coefficients as a function of temperature were studied. The electromechanical coupling factor k26 and piezoelectric coefficient d26 are determined to be ∼30.8% and ∼15.2 pC/N at room temperature, respectively. The large piezoelectric response and zero temperature coefficient of frequency indicate the potential usage of NdCOB crystal for piezoelectric frequency devices over a wide temperature range.