Growth and piezoelectric properties of Sr<inf>3</inf>Ta(Al<inf>0.5</inf>Ga<inf>0.5</inf>)<inf>3</inf>Si<inf>2</inf>O<inf>14</inf> crystals with langasite structure

Abstract

New piezoelectric crystal Sr ₃ Ta(Al _0.5 Ga _0.5 ) ₃ Si ₂ O ₁₄ (STAGS) with ordered langasite structure was successfully grown by Czochralski method. The lattice parameters of STAGS were a = 8.269 Å, c = 5.036 Å. The rocking curve evident the crystal quality declined and the diffraction peak shift slightly from top to bottom. Element analysis revealed the Al ³⁺ was not easy to occupy the C site as Ga ³⁺ in crystal. The piezoelectric coefficients d ₁₁ of STAGS was found to be 5.1pC/N and the resistivity was high up to 4.94×10 ⁶ Ω·m for top part and 7.08×10 ⁶ Ω·cm for bottom part at 700°C, respectively.