Additional file 1: Figure S1. of (La0.97RE0.01Yb0.02)2O2S Nanophosphors Converted from Layered Hydroxyl Sulfate and Investigation of Upconversion Photoluminescence (RE=Ho, Er)

Configuration of laser pumping and UC measurement in JASCO FP-6500 sample chamber. Figure S2. UC luminescence comparison of (La,RE,Yb)2O2S and (La,RE)2O2S under the excitation of 978-nm laser. Table S1. CIE chromaticity coordinates of the (La0.97Ho0.01Yb0.02)2O2S UC phosphor under different excitation power. Figure S3. CIE chromaticity diagram for the UC emissions of (La0.97Ho0.01Yb0.02)2O2S (a) and (La0.97Er0.01Yb0.02)2O2S (b). Table S2. CIE chromaticity coordinates of the (La0.97Er0.01Yb0.02)2O2S UC phosphor under different excitation power. Table S3. Excitation power dependence of the I549/I668 and I527/I668 intensity ratios for the (La0.97Er0.01Yb0.02)2O2S UC phosphor. (DOC 2407 kb

Facile hydrothermal crystallization of NaLn(WO₄)₂ (Ln=La-Lu, and Y), phase/morphology evolution, and photoluminescence

<p>Hydrothermal reaction of Ln nitrate and Na₂WO₄ at pH=8 and 200 °C for 24 hours, in the absence of any additive, has directly produced the scheelite-type sodium lanthanide tungstate of NaLn(WO₄)₂ for the larger Ln³⁺ of Ln=La-Dy (including Y, Group I) and an unknown compound that can be transformed into NaLn(WO₄)₂ by calcination at the low temperature of 600 °C for the smaller Ln³⁺ of Ln=Ho-Lu (Group II). With the successful synthesis of NaLn(WO₄)₂ for the full spectrum of Ln, the effects of lanthanide contraction on the structural features, crystal morphology, and IR responses of the compounds were clarified. The temperature- and time-course phase/morphology evolutions and the phase conversion upon calcination were thoroughly studied for the Group I and Group II compounds with Ln=La and Lu for example, respectively. Unknown intermediates were characterized by elemental analysis, IR absorption, thermogravimetry, and differential scanning calorimetry to better understand their chemical composition and coordination. The photoluminescence properties of NaEu(WO₄)₂ and NaTb(WO₄)₂, including excitation, emission, fluorescence decay, and quantum efficiency of luminescence, were also comparatively studied for the as-synthesized and calcination products.</p

EDTA-assisted phase conversion synthesis of (Gd_0.95RE_0.05)PO₄ nanowires (RE = Eu, Tb) and investigation of photoluminescence

<p>Hexagonal (Gd_0.95RE_0.05)PO₄·<i>n</i>H₂O nanowires ~300 nm in length and ~10 nm in diameter have been converted from (Gd_0.95RE_0.05)₂(OH)₅NO₃·<i>n</i>H₂O nanosheets (RE = Eu, Tb) in the presence of monoammonium phosphate (NH₄H₂PO₄) and ethylene diamine tetraacetic acid (EDTA). They were characterized by X-ray diffraction, thermogravimetry, electron microscopy, and Fourier transform infrared and photoluminescence spectroscopies. It is shown that EDTA played an essential role in the morphology development of the nanowires. The hydrothermal products obtained up to 180 °C are of a pure hexagonal phase, while monoclinic phosphate evolved as an impurity at 200 °C. The nanowires undergo hexagonal→monoclinic phase transformation upon calcination at ≥600 °C to yield a pure monoclinic phase at ~900 °C. The effects of calcination on morphology, excitation/emission, and fluorescence decay kinetics were investigated in detail with (Gd_0.95Eu_0.05)PO₄ as example. The abnormally strong ⁵D₀→⁷F₄ electric dipole Eu³⁺ emission in the hexagonal phosphates was ascribed to site distortion. The process of energy migration was also discussed for the optically active Gd³⁺ and Eu³⁺/Tb³⁺ ions.</p