White-light emission in Yb3+/Er3+/Tm3+- and Yb3+/Er3+/Tm3+/Ho3+-dopedα-NiMoO4nanoparticles

Yb³⁺/Er³⁺/Tm³⁺- and Yb³⁺/Er³⁺/Tm³⁺/Ho³⁺-dopedα-NiMoO₄nanoparticles were synthesized using a microwave hydrothermal method and studied for white-light emission under 980 nm laser diode excitation. White upconversion (UC) light was successfully obtained with the appropriate control of blue, green, and red emissions by successfully tuning the Er³⁺and Ho³⁺concentrations in Yb³⁺/Er³⁺/Tm³⁺- and Yb³⁺/Er³⁺/Tm³⁺/Ho³⁺-dopedα-NiMoO₄, respectively. In addition, the white color emission was shown by the CIE chromaticity coordinates of samples. The energy transfer mechanisms are explained in detail based on the emission spectra and pump power density-dependent UC luminescence intensity in rare earth (Yb³⁺/Er³⁺/Tm³⁺and Yb³⁺/Er³⁺/Tm³⁺/Ho³⁺)-dopedα-NiMoO₄nanoparticles. The results indicate that Yb³⁺/Er³⁺/Tm³⁺- and Yb³⁺/Er³⁺/Tm³⁺/Ho³⁺-dopedα-NiMoO₄nanoparticles can be good candidates for white-light devices.

Improvement of Ultrafiltration for Treatment of Phosphorus-Containing Water by a Lanthanum-Modified Aminated Polyacrylonitrile Membrane

Phosphorus contamination in fresh water has posed a great risk to aquatic ecosystems and human health due to extensive eutrophication. In this paper, we are reporting a lanthanum (La)-modified aminated polyacrylonitrile (PAN) adsorptive membrane for effective decontamination of phosphorus from the simulated water. The PAN membrane was first aminated to introduce the amine group as an active site for La and then followed by the in situ precipitation of La particles. The kinetics study showed that the rapid adsorption occurred within the initial 4 h with the equilibrium established at 8 h. The membrane worked well in the acidic pH region, with optimal pH 4 and 5 without and with the pH control, respectively. The maximum adsorption capacities were 50 and 44.64 mg/g at pH 5 and 7, respectively. The adsorption of phosphorus was not affected by the existence of commonly existing anions except fluorides in water. In the filtration study, it was observed that the removal of phosphorus remained the optimum, although the operating pressure was increased from 1 to 3 bar. The modified membrane was able to treat 0.32 L of a 10 mg/L phosphate solution to meet the maximum allowable limit of 0.15 mg/L for the trade effluent. The mechanism study revealed that the removal was primarily associated with the ion exchange between a phosphorus ion and a hydroxyl group from the La particles.

Upconversion based near white light emission, intrinsic optical bistability and temperature sensing in Er3+/Tm3+/Yb3+/Li+:NaZnPO4 phosphors

NaZnPO₄:Er³⁺/Tm³⁺/Yb³⁺/Li⁺ phosphors have been prepared which show UC based near white light emission, intrinsic optical bistability and temperature-dependent population re-distribution ability.