Materials Chemistry and Physics, Vol.223, 583-590, 2019
Synthesis of high crystalline hierarchical self-assembled MMoO4 (M = Ca, Sr and Ba) super structures: Having hydrophilic surfaces and obvious redshifted photoluminescence behavior
Three-dimensional (3D) hydrophilic surfaced MMoO4 (M = Ca, Sr and Ba) superstructures were successfully synthesized using a surfactant-assisted hydrothermal route. This green chemistry method by use of inexpensive reagents makes procedure simple and highly reproducible. The prepared materials were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), emission/excitation spectra analyses, and Fourier transform infrared (FT-IR), Raman, and ultraviolet-visible (UV-Vis) spectroscopies. The scanning electron microscope (SEM) studies demonstrated that the optimized material can be synthesized at pH 6 and 180 degrees C for CaMoO4 and pH 5 and 220 degrees C for SrMoO4. Prepared materials displayed good dispersion of small-sized gold and the product consisted of a large number of doughnut and sphere-like superstructures for CaMoO4 and SrMoO4, respectively. The result showed that the mean diameters of doughnut and sphere-like particles were about 2.5-5 mu m and 2.5 mu m, respectively and the as-synthesized self-assembled superstructures were composed of nanosheets with the thickness of about 20-50 nm. Also, the SEM micrographs demonstrate that the morphology of the optimized materials for BaMoO4, synthesised at 200 degrees C and pH 5, were particles with hierarchical self-assembled architecture that composed of very long central stems with an average length of about 20-40 mu m in which perpendicular branches was seen. The luminescence properties of the optimized samples with various morphologies have also been investigated and photoluminescence spectra of the samples showed very obvious red-shifted PL emission without using rare earth ions-doped luminescent materials and the energy transfer process from host to rare earth ions.