Yb3+-Ho3+ co-doped germanium-phosphate glasses have been prepared and characterized for its optical properties through measuring photoluminescence and Raman spectra. UV-visible up-conversion emission of holmium ion in Yb3+-Ho3+ co-doped germanium-phosphate glasses has been observed on 980nm excitation. As phosphate was substituted for germanium the red emission Red I decreased at first and then increased later while the green emission Green I decreased and the ratio of Red I to Green I increased. Interestingly, the value of ultraviolet emission intensity was larger than that of the blue and green emission intensity in phosphate glass sample. We believe that Yb3+-Ho3+ co-doped germanium-phosphate glasses might be a potential host material for developing ultraviolet all–solid compact lasers. The possible excitation mechanisms involved in these emissions were discussed, too.

Uniform and well-crystallized octahedral NaGd(MoO4)2:Eu3+ microcrystals have been successfully synthesized by a facile one-step hydrothermal synthesis method without involving any templates. The prepared samples were systematically characterized by powder X-ray diffraction, field-emission-scanning electron microscopy, photoluminescence (PL), and photoluminescent excitation spectra. The starting pH value played an important role in the pure-phase formation and uniform morphology of octahedral microcrystals. Detailed proofs indicated that the growth process of NaGd(MoO4)2:Eu3+ microcrystals was dominated by a nucleation–crystallization-oriented attachment mechanism. Furthermore, the luminescent properties of the as-synthesized NaGd(MoO4)2:Eu3+ microcrystals were investigated, demonstrating that the PL intensity was influenced by the different morphologies, and the bipyramidal octahedra NaGd(MoO4)2:Eu3+ luminescent microcrystals might be applied as an excellent red component for near-UV white light emitting diodes.

CaSnO 3 :Eu 3+ microcrystals with controlled morphology were prepared by a hydrothermal method followed by further calcining treatment without any template or capping reagents. Reactant concentration and reaction time showed strong effects on the phase formation and morphology of the products. The prepared samples were systematically characterized by powder X-ray diffraction, field-emission scanning electron microscopy, photoluminescence ͑PL͒, and photoluminescent excitation spectra. The possible formation mechanism was proposed. Furthermore, PL characterization of CaSnO 3 :Eu 3+ microcrystals was performed and discussed in detail.Nanometer-sized inorganic low dimensional systems exhibit a wide range of optical and electric properties 1 that greatly depend on the crystal shapes due to the association between surface atomic arrangement and material stabilities. 2 Nowadays, research interests have been expanded into controlling the shape of materials and understanding the correlations between the materials properties and their microstructure and morphology. 3-5 However, attempts to prepare inorganic materials with uniform shape and size in large quantities still remain a challenge. 6-11 Considerable strategies have been developed for the growth of inorganic materials with different morphologies, such as flowerlike, 12 star-shaped, 13 and doughnutlike morphology products from inorganic precursors. 14 A further investigation on the parameters that controlled crystal growth was necessary to extend the obtainable inorganic materials with uniform shapes and sizes.Recently, considerable interest in the optical and electrical properties of doped nanoparticles has emerged. Alternative classes of these materials that exhibit unique optical properties are those based on oxide-doped rare-earth ions. 15,16 The perovskite-type alkalineearth stannates ͑MSnO 3 , M = Ca, Sr, and Ba͒ have been extensively studied during the past century, especially on their very interesting application for display phosphor matrix, ceramic materials, thermally stable capacitors in electronic industries, and gas sensor host. 17-19 SnO 4 2− anions are reported to be optically inert and could be a candidate as a host material. 20 At present, many efforts have been devoted to the synthesis of CaSnO 3 microcrystals with various shapes by different methods. 21,22 CaSnO 3 microcubes can be prepared by a hydrothermal method with the assistance of polyvinylpyrrolidone surfactant. 21 Eight-horn or cubic CaSnO 3 microcrystals can be obtained by a precipitation method by the addition of a desired amount of NaOH or HCl solution to the Na 2 SnO 3 aqueous solution. 22 However, little attention has been paid to the luminescence properties of alkaline-earth stannate phosphors. 23-27 Most of the preparation processes employ high calcination temperatures ͑800-1600°C 28 ͒ or the products usually consist of particles with irregular shapes and wide size distributions. The methods mentioned in the literature required high temperature, special conditions, or tedious proced...

Natural radiative lifetimes of nine odd-parity highly excited levels in Eu I and eleven even-parity levels in Eu II have been measured by time-resolved laser-induced fluorescence technique in laser-produced plasma. The lifetime values measured in this paper are in the range from 7.1 to 1520 ns. When they are compared with the previous measurements, good agreement was achieved.