Thermal stress analysis and growth of high quality La3Ga5SiO14 crystals

Langasite (La₃Ga₅SiO₁₄, LGS) crystals have garnered significant attention due to their excellent piezoelectric and photoelectric properties. However, the issue of cracking during the crystal growth process has long remained a persistent challenge in this field. This work numerically simulates the stress distribution of crystals prone to cracking during the Czochralski growth process. The results demonstrate that the thermal stress at the shoulder of the crystal is relatively high, often resulting in surface cracking in this region. By optimizing the temperature field structure, 2-inch crack-free LGS crystals with high macroscopic quality were grown in air. The crystal shows high crystallographic uniformity, with an average rocking curve full width at half maximum (FWHM) of approximately 32.02″ for a 2-inch wafer. The crystal demonstrates excellent optical transmittance (∼80%) and stability after annealed at high-temperature in various atmospheres. These findings provide valuable guidance for achieving large-sized, high-quality LGS crystals.