Y2O2S:Yb/Ho-silica/aminosilane core-shell nanoparticles were prepared by a solid-gas method in combination with polyvinylpyr-rolidone assisted one-step ammoniating method. The core was a single Y2O2S:Yb/Ho with 80 nm in diameter and the shell was silica/aminosilane with around 5 nm in thickness. The results of sedimentation experiment indicated that the nanoparticles could be well-dispersed in ethanol and water to form stable colloids. Since the coating weakened lattice vibration energies of the Y2O2S:Yb/Ho...
yD3+/Tm3+ co-doped and yD3+/Ho3+/Tm3+ tri-doped tellurite glasses were synthesized by fusing the mixture of TeO2, PbF2, AIF3, BaF2, Yb2O3, Tm203 and H0203 in a cortmdum crucible at 850 ℃ for 20 min. The synthesized glasses were characterized by upconversion emission spectra under the excitation of 980 nm laser, and the emission colors were investigated according to the CIE-1931 standards. The results indicated that yD3+/Tm3+ co-doped tellurite glass exhibited blue upconversion emission with favor- able color coordinates of (0.20, 0.07). Yb3+, HO3+ and Tm3+ tri-doped tellurite glasses presented white upconversion luminescence under a single 980 nm laser excitation. Moreover, a very wide range of emission colors could be tuned by altering Ho3+ concentration. Combining the contribution of adjusting Ho3+ concentration and pump power, near equal energy white light was obtained.
Pure γ-Gd2S3 was synthesized by the thermolysis of a single Gd[S2CN(C4H8)]3 phen complex precursor in a flow of argon carrier gas containing sulfur vapor. The complex precursor was decomposed into amorphous Gd2S3 and carbon at about 350 ℃. Crystalline y-Gd2S3 could be achieved at temperature exceeding 600 ℃, and the obtained γ-Gd2S3 presented a very high degree of crystallinity at 800 ℃. Carbon prevented the formation of Gd2O2S impurity in the preparation of y-Gd2S3. However, the carbon blackened the product. At temperature ≥ 1000 ℃, the residual carbon impurity could be efficiently removed by introducing sulfur into the system for the volatile CS2 could be formed in situ via the reaction of sulfur with the deposited carbon. In the meantime, S also promoted the crystallization of γ-Gd2S3 remarkablely.
Monodisperse silica/aminosilane-coated Y 2 O 3:Yb,Ho nanoparticles are prepared via homogenous precipitation combined with a polyvinylpyrrolidone-assisted ammoniation method.The factors that contribute to the success of the coating are examined,and the procedure is optimized.Compared with uncoated nanoparticles,coated nanoparticles exhibit an increased ratio of green to red emission intensity,which can mainly be attributed to the decreased number of surface defects induced by the surface coating.
PANG Tao CAO WangHe XING MingMing LUO XiXian XU ShuJing