A Novel Approach for Monodisperse Samarium Orthovanadate Nanocrystals: Controlled Synthesis and Characterization

A new solvothermal approach has been developed for the synthesis of monodisperse and well-crystallized SmVO 4 nanocrystals with different morphologies from the reaction of Sm(OA) 3 and VO 4 (TOA) 3 complexes in toluene in the presence of surfactant (oleylamine or oleic acid) through a solvothermal pathway. The present solvothermal approach is simple and reproducible and employs a relatively mild reaction temperature. The obtained SmVO 4 nanocrystals were characterized by means of transmission electron microscopy, selected area electronic diffraction (SAED), X-ray diffraction (XRD), Elemental dispersive spectrum, X-ray photoelectron spectra (XPS), UV−visible, thermogravimetric differential thermal analysis TGA−DTA, FTIR, and N 2 adsorption/desorption isotherms (BET) techniques. The SAED and XRD patterns confirmed that the structure of the synthized SmVO 4 nanocrystals is single-crystalline tetragonal. The size, shape, and aspect ratio of products can be readily controlled by adjusting the reaction parameters, such as the nature and amount of surfactant, and the concentration of the metal complex precursors. The SmVO 4 nanocrystals with spherical and hexagonal shapes were obtained by using oleylamine or oleic acid as a nonselective and selective surfactant, respectively, under the same synthesis conditions. Furthermore, the average particle size is tunable from 30 to 3 nm by increasing the oleylamine concentration from 0.025 to 0.43 M in the synthesis solution. The shape evolution from nanocores to nanowires can also be obtained by increasing the metal complex precursor concentration; it is associated with the increase in the chemical potential in the reaction solution. The XPS results revealed only one oxidation state for Sm 3+ and V 5+ on the SmVO 4 nanocrystal surface, even after calcinations compared two oxidation states (e.g., Sm 2+ /Sm 3+ and V 4+ /V 5+ ) of the single samarium oxide and vanadium oxide NPs, respectively. Our synthetic approach can be further extended to the synthesis of other uniform rare earth orthovanadate, molybdate, and tungstate nanocrystals.