Low-temperature aqueous solution growth of the acousto-optic TeO2 single crystals

Abstract

α-TeO₂ is widely used in acousto-optic devices due to its excellent physical properties. Conventionally, α-TeO₂ single crystals were grown using melt methods. Here, we report for the first time the growth of α-TeO₂ single crystals using an aqueous solution method below 100 °C. The solubility curve of α-TeO₂ was measured, and then single crystals with dimensions of 3.5 × 3.5 × 2.5 mm³ were successfully grown using seed crystals that were synthesized from spontaneous nucleation. The as-grown single crystals belong to the P4₁2₁2 space group, evidenced by single crystal X-ray diffraction and Rietveld refinement on powder diffraction. Rocking curve measurements show that the as-grown crystals exhibit high crystallinity with a full-width at half maximum (FWHM) of 57.2′′. Ultraviolet-visible absorption spectroscopy indicates that the absorption edge is 336 nm and the band gap is estimated to be 3.69 eV. The density and Vickers hardness of the as-grown single crystals are measured to be 6.042 g cm⁻³ and 404 kg mm⁻², respectively. Our findings provide an easy-to-access and energy-saving method for growing single crystals of inorganic compounds.