Advanced piezoelectric crystal Ca<inf>3</inf>TaGa<inf>3</inf>Si<inf>2</inf>O<inf>14</inf>: Growth, crystal structure perfection, piezoelectric and acoustic properties

Abstract

A five-component crystal of lanthanum-gallium silicate family Ca ₃ TaGa ₃ Si ₂ O14 (CTGS) was grown by the Czochralski method. The CTGS crystal, like langasite crystals La ₃ Ga ₅ SiO14, possesses unique temperature properties and the fewer number of the Ga atoms in the unit cell makes the density much lower and, consequently, increases the velocity of acoustic wave propagation. The unit cell parameters were determined by the powder diffraction technique. The defects in the CTGS crystal structure were studied by X-ray topography which enables the visualization of growth banding characteristics of crystal grown by Czochralski method. Surface acoustic wave (SAW) propagation in the CTGS crystal was investigated by the high-resolution X-ray diffraction method. The velocities of propagation and power flow angles of SAW in the Yand X-cuts of the CTGS crystal were determined from the X-ray diffraction spectra.