Ni Yaru

Hydrogenation of TiO2 nanosheets with exposed {001} facets for enhanced photocatalytc activity

Hydrogenated {001}-facets-dominated anatase TiO2 nanosheets have O–H bonds and O− on their surface. The high reactive {001} facets were maintained by the formation of Ti–H bonds. A large number of Ti3+ ions and oxygen vacancies were produced by hydrogenation, resulting in improved light absorption and enhanced photocatalytic activity.

Study on Optical Properties and Structure of Sm2O3 Doped Boron-Aluminosilicate Glass

Abstract Sm3+ doped B2O3-Al2O3-SiO2 glasses were prepared by high temperature solid-state method. The absorption spectrum, excitation spectrum, emission spectrum and the effect on concentrations of Sm3+ were investigated at room temperature. The results indicated that, under the excitation of 472 nm, the glass gane visible (VIS) and near infra-red (NIR) emissions at 596, 641, 561, 1075, 1118 and 1177 nm, respectively. The optimum concentration of Sm3+ was determined to be 1.0 mol%. On the other hand, magic angle spin nuclear magnetic resonance (MAS NMR) and infrared (IR) spectra were utilized to characterize the the network structures of Sm2O3 doped boron aluminosilicate glasses. The results showed that network units, namely, [SiO4], [BO3], [BO4], [AlO4] existed in Sm3+ doped B2O3-Al2O3-SiO2 glasses, and Sm3+ existed as network modifier. The higher Sm3+ concentration was, the more units of [BO3] would transit to [BO4].

Optical Properties of Dy3+ Doped in Boroaluminasilicate Glass

Abstract Dy 3+ doped boroaluminasilicate glasses were synthesized in air atmosphere with conventional high temperature process. Optical absorption, emission and excitation spectra of the glasses were measured. Effect of concentration quenching on the lifetime and fluorescence yield was discussed. The pilot study on the changes in emission spectra of Dy 3+ /Tb 3+ , Dy 3+ /Pr 3+ co-doped glasses was carried out. 451 nm was found to be the ideal wavelength among five excitation wavelength in the UV-Vis region from excitation spectra. The fluorescence spectrum of the sample had three major emission bands at 482, 575 and 662 nm, respectively. The strongest emission band peak was at 575 nm. With an increase in Dy 3+ concentration beyond a particular value (1%), the concentration quenching phenomenon occurred. The lifetime of 4 F 9/2 level reduced from 0.9 ms to 0.5 ms when Dy 3+ concentration increased from 0.2% to 4%. The energy transfer from Dy 3+ to Tb 3+ and from Pr 3+ to Dy 3+ were detected in the co-doped glasses.

Synthesis of monodisperse erbium aluminum garnet (EAG) nanoparticles via a microwave method

Abstract Uniform Er3Al5O12 spheres are of great value for fabricating optical ceramics. The highly monodisperse and size-controllable erbium aluminum garnet (EAG) precursors for transparent ceramics were successfully synthesized through a new microwave process. The precursors constituted of ultrafine particles joining together by a hydroxyls formed compact network structure in the absence of SO42−, however, the morphologies of the precursors exhibited spheres with trace amount of SO42−. With manipulated programming of microwave irradiation parameters, narrow distributed particles of 40–50 nm were finally obtained by a separation of nucleation and nanocrystal growth. The mechanism behind the influence of microwave irradiation parameters on the growth of EAG precursors was preliminarily analysed. Easily dispersible and pure phase EAG were obtained at 950 °C. The as-prepared EAG powders were used to fabricate transparent ceramics and transparent polycrystalline EAG ceramics were obtained under hydrogen furnace at 1750 °C for 8 h.

Effects of oxygen defects on structure and properties of Sm0.5Sr0.5CoO3-δ annealed in different atmospheres

Abstract Samples of Sm0.5Sr0.5CoO3–δ were annealed in different atmospheres (Ar, N2, and O2) and temperatures (400–1200 °C), and changes in their masses, structures, surface transport properties, optical properties, and oxygen nonstoichiometries were investigated using thermogravimetric (TG) analyses, X-ray diffraction (XRD) analyses, electrical conductivity measurements, re?ection spectra measurements, and X-ray photoelectron spectroscopy, respectively. The TG analyses, performed in air and an N2 atmosphere, allowed us to determine the changes in the masses of the samples. The results of the XRD analyses elucidated the changes in the structure of the samples under different conditions. The XPS spectra and simulation data indicated that the number of oxygen defects generated in the samples depended on the temperature and atmosphere. At high temperatures, the surface conductivities and full-spectrum reflectivities of the samples decreased with an increase in the number of oxygen vacancies. In an oxidative atmosphere, the samples exhibited outstanding visible and near-infrared light absorption. Furthermore, the samples were highly sensitive to a reducing atmosphere at various temperatures. On the basis of the fact that the properties of Sm0.5Sr0.5CoO3–δ vary with the environment, it has potential use in high-temperature applications such as weather sensors.

Effect of Heat-treatment Temperature on Upconversion Luminescence of β-NaYF 4 :Yb 3+ ,Er 3+ Nano/Microparticles: Effect of Heat-treatment Temperature on Upconversion Luminescence of β-NaYF 4 :Yb 3+ ,Er 3+ Nano/Microparticles

采用溶剂热法和热分解法分别制备纳/微米的β-NaYF 4 :20%Yb 3+ ,2%Er 3+ 晶体. 根据两种不同粒径颗粒的TG-DTA测试分析, 对其进行不同温度的热处理。通过XRD、SEM、FT-IR以及PL等手段研究不同热处理温度对两种粒径的颗粒的尺寸、形貌以及上转换发光性能的影响. 研究结果表明, 随着热处理温度的升高, 纳/微米颗粒的发光性能主要呈现出先升高后下降的趋势。与未作热处理样品对比发现, 适当的热处理(580℃)可以提高纳米颗粒的发光强度, 却不利于改善微米颗粒发光性能。分析认为, 结晶质量的提高、缺陷浓度的降低以及有机配体的去除, 导致了纳/微米颗粒的发光性能的逐步提高。而过高处理温度(>580℃)引起的相转变(β→α)和表面Na 2 CO 3 的生成又大大降低了稀土离子的发光效率。热处理过程中颗粒之间的不同团聚程度是造成纳/微米颗粒发光性能差异变化的主要原因。

Hydrothermal synthesis, structure study and luminescent properties of YbPO4:Tb3+ nanoparticles

Abstract YbPO4:Tb3+ were synthesized by mild hydrothermal method. The luminescent properties, morphologies and structure of the obtained powders were characterized by photoluminescence (PL) spectra, FESEM, X-ray diffractometer (XRD) and FTIR. The results showed that the prepared YbPO4:Tb3+ nanoparticles were pure tetragonal phase and the average grain size varied with increasing of Tb3+ concentration. Hydrothermal temperature was revealed to be the key factor to enhance the emission intensity of YbPO4:Tb3+ phosphors. The spherical nanoparticles could be effectively excited by near UV (369 nm) light and exhibited green performance at 543 nm (5D4→7F5), 489 nm (5D4→7F6) and 586 nm (5D4→7F4). The CIE chromaticity was calculated to be x=0.298, y=0.560. The YbPO4:Tb3+ nanoparticles exhibited potential to act as UV absorber for solar cells to enhance the conversion efficiency.

Synthesis and Characteristic Study on Complexes of Europium(III) and Maleic Acid Doped with Non-Fluorescent Ions

Abstract Complex of europium (III) with maleic acid, and binuclear complexes of europium(III)with maleic acid doped with non-fluorescent ions gadolinium, lanthanum and yttrium, were synthesized. The compositions and structures of complexes were characterized with elemental analysis, single crystal X-ray diffraction, IR and DSC-TG. Fluorescent properties were studied with fluorescence spectrum. The results indicated that the strongest fluorescent complexes were obtained when the ratio of europium and non-fluorescent ion was 8:2. The order of Eu3+ fluorescence strengthened by three doped rare earths was Gd3+ > La3+ > Y3+.

Preparation and laser induced damage properties of rare earth doped BAS glass

Abstract Rare earth doped B2O3-Al2O3-SiO2 glass (RExBAS, x=5, 10, 20; RE=La, Sm) were prepared by solid state reaction method. Optical transmission spectra of such glass were characterized by ultraviolet spectrometers, and 1064 nm laser induced damage performance was investigated through the method of “1-on-1”. The results indicated that there was a strong absorptive peak near 1064 nm in SmxBAS glass, the peak was enhanced with increasing x. While LaxBAS glass was transparent to 1064 nm laser, at the same time, the results of laser induced damage showed that the anti-laser induced damage performance of such glass was strengthened with the addition of rare earth oxide. Furthermore, the laser induced damage threshold (LIDT) of SmxBAS glass was significantly higher than that of LaxBAS glass. Consequently, Sm3+ doping was favor in the improvement of anti-laser induced damage performance for BAS glass.