https://www.ostphotonics.com/products/saw-optical-grade-lithium-tantalate-wafers/
Lithium tantalate (LiTaO3 or LT) crystals can be used to make surface acoustic wave devices, thermoelectric detectors and electro-optical modulators. Lithium tantalate and lithium niobate crystals are multifunctional crystal materials with piezoelectric, ferroelectric, pyroelectric, acousto-optic and electro-optic properties. They are widely used in surface sound wave (SAW) devices, optical communications, laser and electronics industry.