Investigation of the dielectric and piezoelectric properties of ReCa4O(BO3)3 crystals

Piezoelectric ReCa4O(BO3)(3) (ReCOB, Re: rare earth) crystals, including ErCOB, SmCOB, PrCOB and LaCOB, were successfully grown by the Czochralski (Cz) method. The dielectric constants were determined to be epsilon(T)(11)/epsilon(0) = 9.50, epsilon(T)(22)/epsilon(0) = 11.8 and epsilon(T)(33)/epsilon(0) = 9.80 for ErCOB, epsilon(T)(11)/epsilon(0) = 9.70, epsilon(T)(22)/epsilon(0) = 13.9 and epsilon(T)(33)/epsilon(0) = 9.90 for SmCOB, epsilon(T)(11)/epsilon(0) = 9.60, epsilon(T)(22)/epsilon(0) = 15.3 and epsilon(T)(33)/epsilon(0) = 10.0 for PrCOB, epsilon(T)(11)/epsilon(0) = 9.40, epsilon(T)(22)/epsilon(0) = 15.0 and epsilon(T)(33)/epsilon(0) = 9.60 for LaCOB, respectively. The electromechanical coupling factors k(26) and piezoelectric coefficients d(26) were found to be 18.5% (7.6 pCN(-1)), 27.0% (12.7 pCN(-1)), 31.5% (15.8 pCN(-1)) and 25.0% (11.8 pCN(-1)) for ErCOB, SmCOB, PrCOB and LaCOB crystals, respectively. The dielectric and piezoelectric properties as a function of Re3+ ion radius were studied, with maximum values being observed in the PrCOB crystals, due to the similar ion radius of Pr3+ and Ca2+. The relationship between the structure and dielectric/piezoelectric properties of ReCOB crystals was explored, to further optimize the dielectric and piezoelectric properties in ReCOB series crystals.