Size- and shape-tailored hydrothermal synthesis of YVO4 crystals in ultra-wide pH range conditions

Abstract

Yttrium orthovanadate (YVO₄) crystals have been prepared hydrothermally in both strongly acidic and basic media. The effects of vanadium source, acid, addition of sodium hydroxide, chelating reagent, and even solvent on the crystalline size and shape were explored using X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Models for the generation of YVO₄ crystals in both acidic and basic media are proposed from the experimental results. The influence of alkaline concentration on the sizes and shapes of YVO₄ crystals has been investigated, and it has been found that the addition of sodium hydroxide can reduce the crystal sizes of YVO₄. Well-defined YVO₄ microcrystals with clear facets have been prepared, and dispersed YVO₄ nanograins and nanoflakes with dimensions of 5–50 nm have been obtained. Both the size and shape of YVO₄ crystals can be tailored by changing the reaction conditions even though YVO₄ crystals generally show a tetragonal growth habit due to its tetragonal crystallographic symmetry.