Structural and Optical Properties of Ca0.9Cu0.01WO4 Solid Solution Synthesized by Sonochemistry Method at Room Temperature

Precise Sn-Doping Modulation for Optimizing CdWO4 Nanorod Photoluminescence

The cadmium tungstate rods have been given much attention due to their potential for usage in numerous luminescent applications. We have prepared single crystalline Sn-doped Cd_1-xSn_xWO₄ (where x = 0, 1, 3, and 5%) nanorods (NRDs) and characterized them using refined X-ray diffraction and TEM analysis, revealing a monoclinic phase and a crystallite size that decreased from 62 to 38 nm as Sn concentration increased. Precise Sn doping modulation in CdWO₄ NRDs causes surface recombination of electrons and holes, which causes the PL intensity to decrease as the Sn content rises. The chromaticity diagram shows that an increase in the Sn content caused a change in the emission color from sky blue to light green, which was attributed to the increased defect density. The photoluminescence time decay curve of all samples fit well with double-order exponential decay, and the average decay lifetime was found to be 1.11, 0.93, and 1.16 ns for Cd_1-xSn_xWO₄, x = 0, 1, and 5%, respectively. This work provides an understanding of the behavior of Sn-doped CdWO₄ NRDs during electron transitions and the physical nature of emission that could be used in bio-imaging, light sources, displays, and other applications.

Disclosing the Biocide Activity of α-Ag2−2xCuxWO4 (0 ≤ x ≤ 0.16) Solid Solutions

In this work, α-Ag2−2xCuxWO4 (0 ≤ x ≤ 0.16) solid solutions with enhanced antibacterial (against methicillin-resistant Staphylococcus aureus) and antifungal (against Candida albicans) activities are reported. A plethora of techniques (X-ray diffraction with Rietveld refinements, inductively coupled plasma atomic emission spectrometry, micro-Raman spectroscopy, attenuated total reflectance–Fourier transform infrared spectroscopy, field emission scanning electron microscopy, ultraviolet–visible spectroscopy, photoluminescence emissions, and X-ray photoelectron spectroscopy) were employed to characterize the as-synthetized samples and determine the local coordination geometry of Cu2+ cations at the orthorhombic lattice. To find a correlation between morphology and biocide activity, the experimental results were sustained by first-principles calculations at the density functional theory level to decipher the cluster coordinations and electronic properties of the exposed surfaces. Based on the analysis of the under-coordinated Ag and Cu clusters at the (010) and (101) exposed surfaces, we propose a mechanism to explain the biocide activity of these solid solutions.

Rietveld Refinement, Morphology, and Optical and Photoluminescence Properties of a β-Ag1.94Cu0.06MoO4 Solid Solution

Corner-truncated cubic β-Ag_1.94Cu_0.06MoO₄ microcrystals were synthesized using the hydrothermal method. These were investigated by X-ray diffraction, confirming obtention of the spinel structure Fd3̅m. Through Raman spectroscopy are confirmed all modes for the point group of O_h⁷. The E_gap shows a decrease of the band gap from 3.20 to 3.07 eV, with reduction of the conduction band occurring from -0.20 eV (β-Ag₂MoO₄) to -0.13 eV (β-Ag_1.94Cu_0.06MoO₄), suggesting a p-type behavior for the Cu²⁺ ion. The field-emission scanning electron microscopy images confirm the morphological changes for β-Ag₂MoO₄, where potato-like microcrystals were found. Meanwhile, corner-truncated cubic microcrystals for β-Ag_1.94Cu_0.06MoO₄. The photoluminescence (PL) spectrum confirms the increase in the PL emission for β-Ag_1.94Cu_0.06MoO₄, with suppression of the deep defects occurring in the structure caused by oxygen and silver atoms. In contrast, the green region is intensified because of distortions of the Ag-O and Mo-O bonds. Therefore, the β-Ag_1.94Cu_0.06MoO₄ solid solution has PL emission with CCT (4510 K) and CIE coordinates (x = 0.372 and y = 0.433), which could be interesting properties for applications as light-emitting diodes.

Rapid photodegradation and detection of zolpidem over β-SnWO4 and α-SnWO4 nanoparticles: optimization and mechanism

We reported the tin (II) tungstate nanoparticles as the photocatalyst and sensor modifier that were synthesized via chemical precipitation reaction and optimized thru the Taguchi design method. The method predicted the best synthesis conditions that led to smaller particles and desired morphologies. Different techniques were used to characterize the chemical structure, morphology, and purity of the nanoparticles. The photocatalytic behavior of different crystalline forms of the SnWO₄ nanoparticles (α and β) was considered by photodegradation of methylene orange and zolpidem under UV light irradiation, while the average size of β-SnWO₄ and α-SnWO₄ nanoparticles prepared in optimum conditions is about 17 nm and 20 nm, respectively. Efficiencies of degradation of methyl orange and zolpidem on β-SnWO₄, in the presence of UV irradiation, were 93% and 98% and in the presence of α-SnWO₄ were 73% and 82% after 2100 s, respectively. Voltammetric sensing of zolpidem was designed by modification of carbon paste electrode via β-SnWO₄ nanoparticles and investigated for determination of the drug in aqueous solution.