Synthesis, Characterization and Optical Activity of RE-doped ZnW[O.sub.4] Nanorods and Nanospheres by Hydrothermal Method

This work has investigated the effect of different dopants on structure, morphology and optical property of ZnW[O.sub.4]. Rare-earth doped ZnW[O.sub.4] (ZnW[O.sub.4]:RE, with 0.5, 1, and 2 mol% of [Eu.sup.3+] and [Pr.sup.3+]) were successfully synthesized by coprecipitation method followed by microwave-assisted hydrothermal system at 140[degrees]C for 1 h. XRD indicated that the crystals have a wolframite- type monoclinic structure and with the addition of dopants the crystallite size decreased. HR-TEM images revealed interesting homogenous nanorods for pure ZnW[O.sub.4] crystals with grow along (021) direction. For ZnW[O.sub.4]: RE we have found nanospheres morphologies, in which the decreasing crystal size were dependent on the RE doping concentration. IR spectra confirm the crystals structure. Ultraviolet-Visible diffuse reflectance spectra indicated that the optical band gap varies with increasing replacement of [Zn.sup.2+] by RE ions. [E.sub.gap] was characteristic of semiconductor materials. Keywords: microwave-hydrothermal method; nanomaterials; rare earth; semiconductor