A green-emitting phosphor, Eu2+-activated NaCaPO4, was synthesized by the conventional solid-state reaction. The photoluminescence excitation and emission spectra, and the temperature dependence of luminescence intensity of the phosphor were investigated. The results showed that NaCaPO4 : Eu2+ could be efficiently excited by incident light of 280–420 nm, which matched well with the emission wavelengths of near-UV LED chips. NaCaPO4 : Eu2+ has a higher quenching temperature. With an increase in the temperature, the emission bands of NaCaPO4 : Eu2+ show an abnormal blue-shift with broadening bandwidth and decreasing emission intensity. The phosphor has a promising potential for white-light-emitting diodes pumped by ultraviolet chips. The CIE coordinates and luminescence decay (lifetimes) of Eu2+ ions in this monophosphate were discussed in order to further investigate the potential applications.

This study investigated the photoluminescent properties of Tb(3+)-Yb(3+)-, Ce(3+)-Tb(3+)-Yb(3+)-, and Eu(2+)-Yb(3+)-doped KSrPO4. The samples were prepared by a solid-state reaction with various doping concentrations. Emission at near-infrared range was focused on the application of luminescent solar concentrator for solar cells. Quantum cutting (QC) energy transfer was confirmed by the lifetimes of the donor. Near-infrared QC involved emission of Yb(3+) ions was achieved by excitation of Ce(3+), Tb(3+), and Eu(2+) ions, where the energy transfer processes occurred from Ce(3+) to Tb(3+) to Yb(3+), Tb(3+) to Yb(3+), and Eu(2+) to Yb(3+), respectively. In addition, the concentration quenching effect of Yb(3+) ions was avoided by low doping concentrations. The overall quantum efficiencies were calculated, and the maximum efficiency reaches 139%. The energy diagrams for divalent and trivalent rare-earth ions in KSrPO4 host lattice were analyzed. Results of this study demonstrate that heat-stable phosphate phosphors are promising candidates for increasing the efficiency of silicon-based solar cells.

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Bi3TiNbO9 nanoparticles with an acceptor dopant of Ni2+ ion were prepared by the conventional Pechini sol–gel synthesis. The X‐ray polycrystalline diffraction measurements (XRD) and the Rietveld refinements of Bi3TiNbO9 samples were completed. The surface property of Bi3TiNbO9 nanoparticles was investigated by transmission electron microscope, scanning electron microscope), and N2 adsorption–desorption isotherms. Bi3TiNbO9 nanoparticles showed an optical band gap with energy of 3.1 eV in the UV region. While the Ni2+‐doping could greatly reduce the band energy of Bi3TiNbO9:xNi2+ nanoparticles to 2.79 eV (x = 0.05) and 2.61 eV (x = 0.1). This indicates that the Ni‐doped samples could be excited by UV–visible light. The photocatalytic abilities were tested by the photodegradation on methylene blue solution (MB) and phenol solutions excited by visible light. Accordingly, the photocatalytic activity was improved by the Ni‐doping in B‐sites in this Aurivillius‐type structure. The results concluded that Bi3TiNbO9:Ni2+ would be a possible candidate as a visible light‐driven photocatalyst. The effective photocatalysis was discussed on the structure characteristic and experiment such as polarized Aurivillius (Bi2O2)2+ layers, luminescence, and decay lifetimes, etc.

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