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CaWO₄ crystals were prepared by hydrothermal method assisting with phenol-formaldehyde polymer. The morphology can be controlled by polymer, and X-ray diffraction patterns results present a scheelite-type tetragonal structure, characteristic infrared active modes for O–W–O in the range from 500 cm${}^{-1}$ to 4000 cm${}^{-1}$ by Fourier transform infrared spectroscopic techniques. Raman results indicate that the crystals possess seven Raman active modes in the range from 100 cm${}^{-1}$ to 1000 cm${}^{-1}$. A scanning electron microscopy study reveals that the particles exhibit uniform morphology. Luminescent properties were investigated by photoluminescence measurements, multicolor phosphors were obtained when Ca${}^{2+}$ was substituted partly by lanthanide ions.

In this research, rod-like undoped and Zn doped h-MoO₃ thin films were grown on top of MoO₃ seed layers, using hydrothermal technique without adding any surfactant. Seed layers of MoO₃ were coated on top of glass substrates using spray pyrolysis technique. Structural, morphological and optical properties of thin films were examined. XRD pattern analysis showed that the seed layer has orthorhombic crystal structure. Also, it confirms the formation of hexagonal structure for thin films grown by hydrothermal. FESEM images show the formation of long, well-shaped hexagonal rod-likes. UV-Vis spectroscopy reveals band gap increasing from 3.2 eV to 3.54 eV, by increasing Zn.

In this study, transition metal dichalcogenide (TMD) material WS₂ and Au nanoparticles were combined with TiO₂ to enhance the photocatalytic performance under visible light. The WS₂ nanosheets were synthesized from bulk WS₂ via ultrasonic process, and the Au nanoparticles were prepared through the reduction reaction from HAuCl₄. The composite photocatalysts of WS₂/TiO₂/Au, TiO₂/Au, and WS₂/TiO₂ were synthesized by a one-step hydrothermal process. The light absorption property of the composites was determined by ultraviolet-visible (UV-vis) photospectroscopy. Surface analysis of WS₂ nanosheet, TiO₂ nanoparticles, and Au nanoparticles was performed by scanning electron microscopy (SEM). The chemical structure of composites and thickness of WS₂ nanosheets were analyzed by Raman spectra. The photocatalytic activity was measured by methylene blue degradation reaction under visible light. These results revealed the photocatalytic behavior of WS₂/TiO₂/Au, TiO₂/Au, and WS₂/TiO₂ composites, as well as WS₂ nanosheets. The WS₂/TiO₂/Au composite showed improved photocatalytic behavior among all samples. It is believed that the WS₂ nanosheet and Au nanoparticle extend the light absorption range from UV region to the visible region, as well as the WS₂/TiO₂/Au composite reduces the recombination of electrons. This study shows that the enhanced photocatalytic behavior of WS₂/TiO₂/Au composite can be used as photocatalytic applications in the future.

Thin film technology is significant in technological progress and modern research because it allows for the production of optoelectronic devices with improved characteristics. Because of its superior chromatic efficiency, tungsten oxide (WO₃) is one of the best candidates for energy-saving applications. In this study, undoped and tin (Sn)-doped WO₃ films were grown on top of WO₃ seed layers directly by a facile hydrothermal route at a temperature as low as 110^∘C for 24h. The seed layers were also deposited on top of glass substrates using spray pyrolysis. The results of tin doping on the structural, optical, and morphological characteristics of the WO₃:Sn films were studied. X-ray diffraction patterns show that peak intensities increase significantly by adding Sn and the films’ crystallinity was improved by rising Sn content. In the visible region, the average optical transmittance is around 13% and the optical bandgap changes from 2.61eV to 2.81eV, by increasing the dopant amount. Finally, the room temperature photoluminescence of samples shows intense green light emissions. The results of this research can be beneficial for the fabrication and performance optimization of electrical and optical devices such as gas sensors, electrochromic devices, and photosensors.