Optoacoustic properties of thallium phosphorous selenide, Tl3PSe4

Abstract
A new material, Tl3PSe4, has been grown as a single crystal and studied for its optical and optoacoustic properties. It is transparent over the range 0.85–17 μm and has an optoacoustic figure of merit (relative to fused silica) of 1370 (at 1.15 μm). The slow shear wave acoustic velocity is 5.1×104 cm/sec, the lowest recorded in the literature for a solid or a liquid. The low velocity and high refractive index (n ≈ 3) lead to the high figure of merit.