A and B sites doped CaAl12O19: Phase component, energy band, color and photoluminescence tuning, color performance prediction and application for pigments

The polyacrylamide gel method was used to fabricate the Ca1-xCoxAl12O19, Ca1-xNixAl12O19, CaAl12-xInxO19 and CaAl12-xWxO19 (x = 0-0.5) pigments. The phase compositions, energy bands, color and photoluminescence properties of the pigments can be controlled by adjusting the type and content of doping ions. The color of CaAl12O19 changed from white to blue with the Co2+ ion doping, from white to gray green with the Ni2+ ion doping, and from white to bright white with the In3+ and W6+ ions doping. The genetic algorithm optimized back propagation neural network can predict the color properties of CaAl12O19 based pigments. The application of the pigments shows that they can be used in painting, coating and other fields. The Co2+ and Ni2+ doped CaAl12O19 exhibits high blue emission, while In3+ and W6+ doped CaAl12O19 shows strong green emission and the luminescence is highly dependent on the type and content of dopant ion, phase composition and energy transfer.

Strategies for ameliorating the photodegradation efficiency of Mn-doped CdAl2O4 nanoparticles for the toxic dyes under visible light illumination

Worldwide environmental issues have been escalating with the growth of the global economy and become a vital problem. To solve the problems, we require an eco-friendly and sustainable binary catalyst for the degradation of Azo dye pollutants. In this work, magnetically reusable, multifunctional novel Mn-doped CdAl₂O₄ nanoparticles were effectively fabricated by the co-precipitation approach. It was utilized for the degradation of two Azo dyes, exhibiting 96 and 98% Mn (0.050 M)-doped CdAl₂O₄ removal rates under visible light illumination, and presenting improved photocatalytic capability than that of pure and other dopants. More notably, the Mn (0.050 M)-doped CdAl₂O₄ catalyst was recycled using centrifuges without major loss and displays almost similar photodegradation behaviors for six successive runs. According to the ESR measurements, outcome and quenching tests affirmed that ^.OH^- and h⁺ radicals were better reactive species responsible for Azo dyes removal. A possible photodegradation reaction mechanism underlying the elimination of Azo dyes by Mn (0.050 M)-doped CdAl₂O₄ catalyst is also proposed. Elaborated analyzes by variable reaction parameters such as the role of reactive species and catalyst dosage, pH, COD and irradiation time in the degradation route was also discussed. We assume that our outcomes will provide novel insights into using a highly effectual Mn (0.050 M)-doped CdAl₂O₄ catalyst, with possible applications in the treatment of both industrial and domestic wastewater.

Effect of Microstructure on Photo-Induced Current Characteristics of Eu2+-Doped SrAl2O4

Research interest is active in Eu2+/Dy3-doped SrAl2O4 phosphors, and the photocurrent characteristics of Eu2+-doped SrAl2O4 without Dy3+ was investigated extensively. However, it exhibits a low photocurrent of ~1 μA owing to high resistance. In this study, the changes in a photo-induced current with grain size were examined. The effect of the processing methods on the microstructure and photocurrent characteristics of Eu2+-doped SrAl2O4 phosphors was investigated. (Sr0.99Eu0.01)Al2O4 powders were synthesized using a conventional solid-state method and calcined at 1350 °C under a 3% H2/(Ar + H2) reducing gas atmosphere. Sample pellets were fabricated as conventional and hot-press-sintered bodies at 1400 °C. A thin film of the sample was deposited on an alumina substrate by radio-frequency magnetron sputtering. Scanning electron microscopy revealed that the hot-press-sintered body has larger grains than the conventionally sintered body. The photo-induced current of the hot-press-sintered body at 400 lx was ~100 and ~1000 times higher than those of the conventionally sintered body and thin film, respectively. Impedance analysis confirmed that this dramatic increase in the photo-induced current is closely related to the increase in the grain size and crystallinity of the sample. This study verifies the applicability of Eu2+-doped SrAl2O4 as both a phosphor and photosensor.