The growth and thermal, electrical properties characterization of Ba2TiSi2O8 piezoelectric crystal

• Raw material ratio was optimized by using the efficient segregation coefficient of different components in the BTS crystal.
• The thermal properties of the BTS crystal were systematically studied at elevated temperature.
• The resistivity of the BTS crystal was higher than those of langasite-type crystals.

Ba2TiSi2O8 (BTS) crystals were successfully grown by the Czochralski method. The raw material ratio was optimized according to the effective segregation coefficient keff of different components in the BTS crystal. The thermal properties of the BTS crystal were systematically studied at elevated temperature, including thermal expansion, specific heat, thermal diffusivity and thermal conductivity. The variations of the thermal expansion coefficients αα33 and αα11 in the temperature range of 25–185 °C were small, whereas those in the temperature range of 185–1000 °C were 17.14×10−6/°C and 4.73×10−6/°C, respectively. A strong anisotropic characteristic in the thermal expansion ratio is associated with the lamellar structure of the BTS crystal. The thermal conductivity increased slowly as the temperature rises. The piezoelectric strain constant d33 of the BTS crystal was determined to be 4.5 pC/N at room temperature using a quasi-static d33 meter. The electrical resistivity of the BTS crystal was investigated at temperatures up to 900 °C, the resistivity ρrρr of the BTS Z-cut sample was 2.06×109 Ω cm at 800 °C, which is three orders of magnitude higher than that of a Ca3TaGa3Si2O14 (langasite-type crystal) X-cut sample (7.15×106 Ω cm) at the same temperature. Thermal and electrical properties have shown that BTS crystal is a potential alternative material for the high temperature piezoelectric sensors.