Chenggang Zuo

Luminescent properties of Tb3+ and Gd3+ ions doped aluminosilicate oxyfluoride glasses.

Tb(3+) and Gd(3+) ions doped lithium-barium-aluminosilicate oxyfluoride glasses have been prepared. The transmission, emission and excitation spectra were measured. It has been found that those Tb(3+)-doped lithium-barium-aluminosilicate oxyfluoride glasses exhibit good UV-excited luminescence. The luminescence intensity of Tb(3+) ion increases for those (Tb(3+), Gd(3+))-codoped glasses. Energy transfer process from Gd(3+) ion to Tb(3+) ion is indicated.

Structure and property of multicomponent germanate glass containing Y2O3

Abstract CaO–BaO–Al2O3–SiO2–GeO2 glasses doped with 0·00–16·67 wt-% Y2O3 have been prepared by conventional melt quenching method. The influence of Y2O3 addition on the properties and structure of the glasses has been investigated. The results show that, with the introducing of Y2O3, the density, glass transition temperature and thermal expansion coefficient of the glass increase but the chemical durability declines. In addition, compared with the glass without Y2O3, the bend strength of the glass including 4·76 wt-% Y2O3 increased from 54 to 110 Mpa. The possible mechanism is that yttria acts as a network former in the structure and makes the island shape network unit repolymerisation by forming Ge–O–Y bond. The absorption strength caused by hydroxyl vibration decreased up to completely disappearance as the Y2O3 content increased continuously. The introducing of yttria in the composition causes the conversion from four coordination to higher coordination germanium, which decreases non-bridge oxygen (NBO) and weakens hydroxyl characteristic absorption.

Luminescence properties of Tb3+-doped borosilicate scintillating glass under UV excitation

Transparent Li₂O-BaO-La₂O₃-Al₂O₃-B₂O₃-SiO₂ glasses doped with Tb(3+) ion were prepared by high temperature melting method. Luminescence properties of Tb(3+)-doped borosilicate glasses have been investigated by transmission, excitation, emission and luminescence decay measurements. The transmission spectrum shows the glass has good transmittance in the visible region. Under the 236 nm UV excitation the intense green emission from (5)D₄ level is observed in Tb(3+)-doped borosilicate glass, comparable in intensity to the violet-blue emission starting from the (5)D₃ level. The green emission intensity of Tb(3+) ion firstly increases and then decreases with the decreasing B₂O₃/SiO₂ ratio in glass matrix. (5)D₄→(7)FJ (J=6, 5, 4 and 3) transitions of Tb(3+) ion in borosilicate glass are greatly enhanced with increasing concentration of Tb(3+) through the cross relaxation [Tb(3+) ((5)D₃)+Tb(3+) ((7)F6)→Tb(3+) ((5)D₄)+Tb(3+) ((7)F₀)] between two Tb(3+) ions. Luminescence decay time of 2.13 ms is obtained for the emission transitions starting from (5)D₄ level in 2.5Li₂O-20BaO-20La₂O₃-2.5Al₂O₃-20B₂O₃-35SiO₂-0.5Tb₄O₇ glass. The results show that Tb(3+)-doped borosilicate glasses would be potential candidates for scintillating material for static X-ray imaging.

Fabrication of three-dimensional porous cobalt network-supported cobalt oxides nanoflake arrays for electrochemical energy storage

Smart combination of porous metal with metal oxides is important for the construction of high-performance electrochemical devices. Herein, we report three-dimensional Co network-supported Co3O4 nanoflake arrays by a facile electrodeposition and following hydrothermal process. 3D Co networks with porous branches and interconnected pores are well formed and used as the skeleton for the growth of porous Co3O4 nanoflake arrays. High porosity and integrated growth are combined in the composite electrode. As an anode material for lithium ion batteries, the Co network-supported Co3O4 nanoflake array electrode exhibits a high first discharge capacity (1164 mAh g−1 at 0.5 A g−1), good cycling stability (714 mAh g−1 after 100 cycles) and enhanced rate capability. The proposed method is useful for the construction of other porous metal/metal oxide composite films for application in electrochemical energy storage and catalysis.

Research on Zr50Al15Ni10Cu25 bulk amorphous alloys prepared by mechanical alloying and low pressure sintering

Abstract Amorphous Zr50Al15Ni10Cu25 alloy powders were fabricated by mechanical alloying technique with commercially pure element powders. The effects of small amount of C, Si3N4 and SiC powders addition on the thermal stability and crystallisation behaviour of the Zr50Al15Ni10Cu25 amorphous alloy were investigated. The blended powders were compacted into bars by oil hydraulic press, and were sintered in argon atmosphere at different temperatures and pressures. The samples before and after sintering were characterised by X-ray diffraction, scanning electron microscopy, differential scanning calorimetry and electron tensile testing machine. The results demonstrated that a proper addition of Si3N4 powders to the amorphous matrix can improve the thermal stability of the matrix. Suitable additives can help to improve the density and mechanical properties of the matrix in sintering process.

Luminescence and energy transfer of Tb3 +–doped BaO–Gd2O3–Al2O3–B2O3–SiO2 glasses

Transparent Tb3+-doped BaO-Gd2O3-Al2O3-B2O3-SiO2 glasses with the greater than 4g/cm3 were prepared by high temperature melting method and its luminescent properties have been investigated by measured UV-vis transmission, excitation, emission and luminescence decay spectra. The transmission spectrum shows there are three weak absorption bands locate at about 312, 378 and 484nm in the glasses and it has good transmittance in the visible spectrum region. Intense green emission can be observed under UV excitation. The effective energy transfer from Gd3+ ion to Tb3+ ion could occur and sensitize the luminescence of Tb3+ ion. The green emission intensity of Tb3+ ion could change with the increasing SiO2/B2O3 ratio in the borosilicate glass matrix. With the increasing concentration of Tb3+ ion, 5D4→7FJ transitions could be enhanced through the cross relaxation between the two nearby Tb3+ ions. Luminescence decay time of 2.12ms from 546nm emission is obtained. The results indicate that Tb3+-doped BaO-Gd2O3-Al2O3-B2O3-SiO2 glasses would be potential scintillating material for applications in X-ray imaging.