Piezoelectric crystals of langasite, langatate and Ca₃TaGa₃Si₂O₁₄ (CTGS) with langasite structure were broadly used in high temperature sensors in recent years. The high content of gallium made these crystals much more expensive compared than quartz. A bulk single crystal Ca₃Ta(Al_0.9Ga_0.1)₃Si₂O₁₄ (CTAGS) of langasite structure in which 90% percent of gallium was replaced by aluminum was successfully grown by Czochralski technique. The as-grown CTAGS crystal has similar growth habits of CTGS with the dimensions of 20 mm in thickness, 70 mm in width and 80 mm in length. The piezoelectric constant d₁₁, the dielectric constant ε₁₁, the electromechanical coupling coefficient k₁₂, the mechanical quality factor Q, the electric resistivity, and dielectric loss of x-cut plate of CTAGS were measured under different temperatures from room temperature up to 900ºC. The d₁₁ rise from 3.99 pC/N to 5.67 pC/N while rise from 13.7% to 15.4%. Compared with reported data, it is found that at temperature below 600ºC, CTAGS crystal has highest resistivity among langasite structure crystals. The advantages of low cost of raw material, easy to grow bulk crystal, combined with the properties of the high resistivity make CTAGS a potential materials for high temperature application.

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