The escalating pollution of aquatic systems by synthetic dyes, demands the development of eco-friendly and high-performance photocatalytic materials for environmental remediation. In this study, Na, Al co-doped titanium dioxide (SAT) nanoparticles are synthesized via a hydrothermal route, followed by calcination at 400, 500, and 600 ℃ to modulate their structural, dielectric, and photocatalytic properties. Comprehensive characterization of SAT samples confirmed the effective incorporation of Na and Al into the TiO2 lattice using X-ray diffraction (XRD), Raman spectroscopy, Photoluminescence (PL), and X-ray photoelectron spectroscopy (XPS). Scanning electron microscopy of SAT samples revealed a homogeneous spherical morphology of particles. A significant enhancement in the dielectric constant is observed particularly of SAT 500 even at high frequency due to optimized polarization, achieved at 500 ℃ calcination temperature. SAT 500 also showed the highest photocatalytic activity with 98.7
Magnetic ferrite is an important material active in the field of photocatalysis. In this work, three morphologies of BiFeO3 (microcubes, microplates, and nanoparticles) were prepared via hydrothermal and sol-gel methods, respectively. A comprehensive characterization was performed to evaluate phase structure, morphology, optical absorption, surface photovoltaic response, catalytic performance, and magnetic property. The results indicated that a pure-phase BiFeO3 microcube could be obtained under strongly alkaline hydrothermal conditions, whereas BiFeO3 microplates were obtained by introducing the surfactant CTAB. The BiFeO3 nanoparticles synthesized by the sol-gel method exhibited an enhanced photogenerated charge separation efficiency due to the nanometer effect. The photocatalytic performance of BiFeO3 was dictated primarily by grain-size-controlled charge separation. BiFeO3 microcubes possessed the narrowest band gap (1.26 eV) and even a nearly full-spectrum solar response, yet their 10 μm grains imposed long carrier-diffusion paths and a low density of surface active sites, resulting in the weakest surface photovoltage response and only 8.9
Bi2O3 was crystallized in the glass system of 40Bi2O3-40B2O3-20TiO2 (in mol%) using the melt-quench technique. The structure, phase, and chemical composition were evaluated using X-ray diffraction, Raman Spectroscopy, Transmission electron microscopy, and X-ray photoelectron spectroscopy. Methylene blue dye was utilized as a model contaminant to measure the degradation performance of Bi2O3 catalyst. The catalytic dye degradation performance was examined under sonocatalysis, visible light photocatalysis, and a combined sono-photocatalysis system. Among these, the highest degradation rate of 0.00276 min- 1 was achieved in the sono-photocatalysis process. Furthermore, the degradation efficiency dropped to 17% in the presence of p-benzoquinone (pBQ), indicating that superoxide radicals are likely the predominant reactive oxygen species contributing to dye degradation. Additionally, the photocatalytic activity was also evaluated under natural sunlight, exhibiting a degradation performance of 86% after 5 h of direct solar irradiation.
In this study, bismuth tungsten oxide powders were synthesized via a scalable solid-state reaction method at three different temperatures: 400 degrees C, 600 degrees C, and 800 degrees C. The effects of calcination temperature on structural, morphological and gamma-ray shielding properties were systematically investigated compared to the mixture sample of bismuth oxide and tungsten oxide. X-ray diffraction analysis confirmed the formation of a well-defined orthorhombic phase at 800 degrees C, with increasing crystallinity compared to lower temperatures. SEM analysis revealed that increasing the treatment temperature from 400 degrees C to 800 degrees C leads to particle growth and morphological evolution in Bi2WO6, supporting the structural changes observed in XRD. Additionally, smaller particles at lower temperatures form a more uniform composite with CMC by effectively filling interstitial gaps. The gamma-ray shielding performance was first determined through experimental measurements, and then complementary Phy-X/PSD calculations and GAMOS simulations were performed to extend the analysis across a broader energy range of 122 keV to 1408 MeV. At 1275 keV, the sample synthesized at 800 degrees C exhibited the highest mass attenuation coefficient of 0.060 cm2/g, the lowest half-value layer of 4.752 cm, and the shortest mean free path of 6.855 cm, indicating a trend of enhanced attenuation compared to samples synthesized at lower temperatures. In contrast, as the synthesis temperature decreases, the probability of photons interacting with electrons increases due to the coexistence of many structures in different phases and morphological irregularities, resulting in improved gamma ray shielding performance at low energies. These quantitative improvements demonstrate that thermally optimized bismuth tungsten oxide samples are promising non-toxic, lead-free candidates for efficient gamma-ray shielding applications.
Terbium zirconates, Tb2Zr2-xO7-2x (x = 0-1, step = 0.125), were prepared by a co-precipitation route and sintered at 1400 degrees C. The bulk structures were characterized by powder X-ray, neutron and electron diffractions while the vibrational modes and electronic structures were investigated using Raman and diffuse reflectance spectroscopies. The results showed that all materials possess fluorite structures under various compositional stoichiometries, with a linear cell expansion upon increasing x from 0 to 1. Despite the high structural symmetry and simplicity, the fluorite-structured materials can accommodate atomic disorders and oxygen vacancies without losing crystallinity, making them essential for materials applications in severe conditions, especially for high temperature, harsh chemical, and extreme radiation environments.
