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

alpha-TeO2 is widely used in acousto-optic devices due to its excellent physical properties. Conventionally, alpha-TeO2 single crystals were grown using melt methods. Here, we report for the first time the growth of alpha-TeO2 single crystals using an aqueous solution method below 100 degrees C. The solubility curve of alpha-TeO2 was measured, and then single crystals with dimensions of 3.5 x 3.5 x 2.5 mm(3) were successfully grown using seed crystals that were synthesized from spontaneous nucleation. The as-grown single crystals belong to the P4(1)2(1)2 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.