Influence of growth conditions on the optical, electrical resistivity and piezoelectric properties of Ca₃TaGa₃Si₂O₁₄ single crystals

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Piezoelectric Ca₃TaGa₃Si₂O₁₄ (CTGS) single crystals are grown by the Czochralski technique and investigated in detail for high temperature sensor applications. The influence of the oxygen partial pressure during the growth on material properties is investigated by the use of Ir crucibles, as well as Pt ones. Colorless crystals are obtained, indicating that the typical yellowish coloration of CTGS crystals is related with the use of Ir-crucibles. Colored crystals present three absorption bands at 340, 450 and 1790 nm, however, related crystal defects do not affect the electrical properties of grown crystals. Dielectric and piezoelectric properties do not vary significantly with the growth conditions. Instead, it is found that the electrical resistivity depends on the oxygen partial pressure and it is higher for CTGS crystals grown under oxygen-less atmosphere.