β-ZnMoO4 microcrystals synthesized by the surfactant-assisted hydrothermal method: Growth process and photoluminescence properties

In this communication, we investigate the effect of different surfactants: cetyltrimethylammonium bromide (CTAB), sodium dodecyl sulfate (SDS) and polyvinylpyrrolidone (PVP-K40) on the growth process of zinc molybdate (β-ZnMoO4) microcrystals synthesized under hydrothermal conditions at 140 °C for 8 h. These microcrystals were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), and photoluminescence (PL) measurements. XRD patterns proved that these crystals are monophasic and present a wolframite-type monoclinic structure. FE-SEM images revealed that the surfactants modified the crystal shapes, suggesting the occurrence of distinct crystal growth processes. The CTAB cationic surfactant promotes the hindrance of small nuclei that leads to the formation of rectangle-like crystals, SDS anionic surfactant induces a growth of irregular hexagons with several porous due to considerable size effect of counter-ions on the crystal facets, PVP-K40 non-ionic surfactant allows a reduction in size and thickness of plate-like crystals, while without surfactants have the formation of irregular plate-like crystals. Finally, the PL properties of β-ZnMoO4 microcrystals were explained by means of different shape/size, surface defects and order-disorder into lattice.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Monophasic β-ZnMoO4 crystals were synthesized by the hydrothermal method (140 °C/8 h). ► Growth mechanism of β-ZnMoO4 microcrystals prepared with different surfactants. ► Effect of surfactants on the photoluminescence behavior of β-ZnMoO4 microcrystals.