High temperature piezoelectric single crystal ReCa4O(BO3)3 for sensors

Large size and high quality ReCa4O(BO3)3 single crystals were grown by the Czochralski pulling method. In this work, the electrical properties were investigated at room temperature and elevated temperature for YCa4O(BO3)3 (YCOB). The dielectric permittivity, piezoelectric strain coefficient and electromechanical coupling were found to be on the order of 11, 6 pC/N and 12.5%, respectively, with a high piezoelectric voltage coefficient around 0.067 Vm/N. The electrical resistivity of YCOB was found to be 2times108 Ohm.cm at 800degC, with Q values of >4,500 at 950degC. The frequency/temperature coefficient of YCOB was found to be -75 ~ -85 ppm/K in the temperature range of 30-950degC, depending on the crystal orientation. Together with its temperature independent properties, ReCOB crystals are promising candidates for sensing applications at elevated temperatures.