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

Abstract

Yttrium orthovanadate (YVO 4 ) 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 YVO 4 crystals in both acidic and basic media are proposed from the experimental results. The influence of alkaline concentration on the sizes and shapes of YVO 4 crystals has been investigated, and it has been found that the addition of sodium hydroxide can reduce the crystal sizes of YVO 4 . Well-defined YVO 4 microcrystals with clear facets have been prepared, and dispersed YVO 4 nanograins and nanoflakes with dimensions of 5-50 nm have been obtained. Both the size and shape of YVO 4 crystals can be tailored by changing the reaction conditions even though YVO 4 crystals generally show a tetragonal growth habit due to its tetragonal crystallographic symmetry.

Methanol–Water System for Solvothermal Synthesis of YVO4:Eu with High Photoluminescent Intensity

“…According to SEM observations, the powder consisted of aggregated flakes, which included B10 nm spherical particles. A very similar morphology was described by H. Wu,11 when acetic acid was used as an additive in the hydrothermal synthesis of YVO 4 . The change from flake-like to raspberry-like shape became pronounced when the solution temperature exceeded the critical temperature of methanol.…”

“…Hydrothermal systems offer higher diffusivity and lower viscosity, which facilitates mass transport, while the solvents possess higher dissolving power. 10 Recently, the hydrothermal method was applied to the synthesis of YVO 4 by H. Wu et al, 11 who synthesized welldefined YVO 4 microcrystals with clear facets in strongly acidic media as well as nanoflakes with dimensions of 5-50 nm in basic media. X. Wu et al 12 reported the synthesis of YVO 4 nanorods and microtubes by the hydrothermal method using (NH 4 ) 0.5 V 2 O 5 nanowires and porous silicon as templates.…”

Rapid synthesis of nanocrystalline CeVO 4 by microwave irradiation

“…The size of sample synthesized at neutral medium (pH ¼ 7) is much smaller than those at acidic and basic media. The dependence of particle size on pH value has been investigated in hydrothermal synthesis of YVO 4 [12,13]. In the basic media, the following reactions would occur:…”

Synthesis of nanocrystalline YVO4:Eu red emission phosphor with high fluorescence intensity by hydrothermal method using original vanadium-peroxo-citrate complex

“…They have studied the influence of various experimental conditions including type of mineralizer, solution pH and process temperature on the growth of YVO4:Nd single crystals for possible laser applications. H. Wu et al 18) demonstrated that hydrothermal method can be used for the synthesis of YVO4 microcrystals as well, and strongly acidic solution favors formation of crystals with well-defined facets, while basic media results in precipitation of flakes of 5-50 nm size. (NH4)0.5V2O5 nanowires and porous silicon as templates allowed X. Wu et al 19) to prepare YVO4 in the form of nanorods and microtubes by the hydrothermal method.…”