•Structure change of Sr2SnO4:RE3+ (RE = Sm, Eu) is observed with the increasing of Sm3+ (Eu3+).•Sm3+ and Eu3+ doped Sr2SnO4 shows the nonlinear emission.•The red emission of Sr2SnO4:Eu3+ is improved with the increasing of Eu3+.Sr2-x/2Sn1-x/2O4:xSm3+ (0 ≤ x ≤ 0.23) and Sr2-y/2Sn1-y/2O4:yEu3+ (0 ≤ y ≤ 0.17) are prepared by the solid-state reaction. The structural properties, absorption, excitation and emission spectra are measured for the obtained powders. The XRD results indicate a small structure change of Sr2-x/2Sn1-x/2O4:xSm3+ and Sr2-y/2Sn1-y/2O4:yEu3+ due to Sm3+ and Eu3+ content increase. As shown by the absorption spectroscopy, Sr2SnO4 can efficiently absorb the energy in the region of 200–350 nm. The emission spectra indicate that the variation of the emission intensity of Sr2-x/2Sn1-x/2O4:xSm3+ and Sr2-y/2Sn1-y/2O4:yEu3+ is nonlinear. The emission intensity of Sr2-x/2Sn1-x/2O4:xSm3+ increases when x < 0.01, then decreases when 0.01 < x < 0.07, and increases again x > 0.07. Two emission maxima are observed when x = 0.01 and 0.19. The change curve of the emission intensity for Sr2-y/2Sn1-y/2O4:yEu3+ (0 ≤ y ≤ 0.17) is similar to that of Sr2-x/2Sn1-x/2O4:xSm3+ (0 ≤ x ≤ 0.23). The Eu3+ emission reaches the maximum when y = 0.03 and 0.11. We call this phenomenon as two quenching concentrations. This phenomenon is exotic in phosphors.Change curve of the relative emission intensity of Sr2-y/2Sn1-y/2O4:yEu3+ under 394 nm excitation; the insert table is the 5D0→7F2/5D0→7F1 emission intensity ratios.Download high-res image (84KB)Download full-size image

•5D0 → 7F2 integrated emission intensity of LaPO4:Eu3+ was higher than 5D0 → 7F1 transition.•VUV luminescent intensities of LaPO4:Eu3+ nanowires were maintained in a certain value.•Self-purification phenomenon is observed in LaPO4:Eu3+ nanowires.A series of different concentrations of LaPO4:Eu3+ phosphors with the morphology of nanowires were successfully prepared by a precipitation method. It was observed that the integrated intensity of 5D0 → 7F2 transition of Eu3+ was higher than its 5D0 → 7F1 transition when the sintering temperature was at 600 °C. The most interesting phenomenon was that the doping concentrations of LaPO4:Eu3+ nanowires were changed in a large range (5–15%), the photoluminescence intensities were maintained in a certain value. This phenomenon was not observed in the bulk LaPO4:Eu3+ phosphors. A detailed explanation to this phenomenon was given.

Hexagonal prism (La, Ce, Tb)PO4 green phosphors have been successfully prepared via a precipitation method route at ambient pressure from aqueous solution. The precipitation was obtained from lanthanide-nitrate complexes and (NH4)2HPO4 with citric acid as a structural modifier. The prism length diameter ratio and size can be tailored by varying the content of citric acid and the acidity of the solution, respectively. The mechanism of how the citric acid and acidity affect morphology has also been studied. Scanning electron microscopy, transmission electron microscopy, high-resolution transmission electron microscopy, X-ray diffraction, and differential thermal analysis-thermogravimetry were used to characterize the morphology of the products and investigate the possible mechanism of formation and growth of the hexagonal prism. Furthermore, photoluminescence (PL) properties of (La, Ce, Tb)PO4 products were also carried out and compared with those of commercial phosphors.

The photoluminescence properties of Y1−x(PO3)3:xEu3+ (0