Morphology and photoluminescence of PbMoO₄ powders on the influence of polyvinyl alcohol (PVA)

Full text: Molybdates and tungstate-based oxides constitute an important class of materials that exhibit various functional properties; in particular, metal molybdates have received special attention due to their novel and intriguing properties for widespread technological applications. Molybdates of relatively large bivalent cations (ionic radius >0.99 Å: Ca, Ba, Pb, Sr) usually exist in the so-called scheelite structure form and have attracted considerable interest due to their promising technological importance in a broad range of applications such as photoluminescence, scintillator materials, humidity sensors, and catalysis. As an important member of this family, lead molybdate (PbMoO₄ ) has gained increasing interest due to its use in a wide range of technological and theoretical fields, and experimental studies on the optical properties of lead molybdate have been published by different research groups [1]. For this study, lead molybdate (PbMoO₄ ) microcrystals were prepared by the coprecipitation method and processed using a conventional hydrothermal method at 120 °C for 10 min with polyvinyl alcohol (PVA) as the capping agent. Characterized by X-ray diffraction, micro-Raman spectroscopy, and their morphology was investigated by field-emission gun scanning electron microscopy (FEG-SEM). The optical properties were analyzed by ultraviolet-visible (UV-vis) absorption spectroscopy and photoluminescence (PL) measurements. XRD patterns and MR spectrum indicate that the PbMoO₄ microcrystals have a scheelite-type tetragonal structure. FE-SEM images reveal that the PVA promotes the aggregation of several octahedrons and the formation of large porous stake-like PbMoO₄ microcrystals. [1] M.R.D. Bomio, R.L. Tranquilin, F.V. Motta, C.A. Paskocimas, R. M. Nascimento, L. Gracia, et al., J. Phys. Chem. C 117 (2013) 21382–21395. (author)