新型稀土钙硼酸盐高温压电晶体的生长与性质表征

Rare-earth calcium oxyborate crystals ReCa4O(BO3) (ReCOB, Re: rare-earth elements) are promising high temperature piezoelectric crystals. In this work, new oxyborate crystals TmCOB, [YxSm(1-x)]Ca4O(BO3)3 (YSmCOB), [YxGd(1-x)]Ca4O(BO3)3 (YGdCOB) and [GdxLa(1-x)]Ca4O(BO3)3 (GdLaCOB) were grown by using the Czochralski pulling method for high temperatrue piezoelectric investigations. Dielectric, elastic and piezoelectric peroperties were studied taking advantage of the impedance method, where the piezoelectric coefficients were determined to be on the order of d12=3.5-3.8 pC/N, and d26=6.8-8.0 pC/N at room temperature. In addition, the temperature dependent behaviours of electro-elastic constants for these crystals were studied from room temperature to 900oC, where YGdCOB crystals were found to show high temperatrue stability of piezoelectric coefficient d26, with vairaiton lower than -3% over the test temperature range, promising for high temperature piezoelectric applications.