Papers by Author: An Xian Lu

Abstract: The present investigation aims at elucidating the photoluminescence (PL) behaviour of Tb³⁺ doped SiO₂–M₂O₃ (M=Al, Ga)–LiF–CaF₂ optical glasses. The absorption spectra of these glasses have revealed the absorption bands due to ⁷F₆ → (⁵L₈, ⁵G₃, ⁵L₉, ⁵G₄, ⁵D₂, ⁵G₅), ⁵L₁₀, (⁵G₆, ⁵D₃) and ⁵D₄ transitions. The Tb³⁺ excitation bands are assigned to the electronic transitions of 4f⁸ → 4f⁷5d¹ and 4f⁸ → 4f⁸. The PL spectra with the excitation wavelength 378 nm recorded at room temperature of these glasses have exhibited the following emission transitions: ⁵D₄ → ⁷F_J (J = 6, 5, 4, 3). An attempt has also been made to throw some light on the relationship between the structural modifications and luminescence efficiencies of both the two glasses. And found the fluorescence intensity of 543 nm emission in SGLCT is 46% higher than that in SALCT due to the different metal oxides viz., Ga₂O₃ and Al₂O₃.

Abstract: The Yb3+-doped silicate and phosphate laser glasses were prepared by using of traditional melt quenching technology, and the physical and spectral properties were investigated. The results show that the stimulated emission cross section and the fluorescence lifetime are 0.67×10-20cm2 and 1200μs for the silicate glass, and 0.75×10-20cm2 and 1000μs for the phosphate glass respectively. And silicate glass’s mechanical and thermal properties were better than that of phosphate glass. But Yb3+-doped phosphate glass has lower nonlinear refraction index n2. Both Yb3+-doped silicate and phosphate glasses are possible to be used as laser medium.

Abstract: The Li2O-ZnO-Al2O3-SiO2 system glasses with varying content of K2O were prepared. Crystallization processes of these glasses were investigated using X-ray diffraction (XRD) and differential scanning calorimetry (DSC). Microstructure of the glass-ceramics was studied using scanning electron microscopy (SEM). The sequence of crystallization of Li2O-ZnO-Al2O3-SiO2 glasses can be divided into three stages such as crystallization of β1-Li2ZnSiO4, crystallization of Li2Al2Si3O10 and conversion of β1-Li2ZnSiO4 to γ0-Li2ZnSiO4. The K2O content doesn’t vary the crystallization sequence but enhances the crystallization of β1-Li2ZnSiO4. At the same time the introducing of K2O in Li2O-ZnO-Al2O3-SiO2 system hinders the crystallization of Li2Al2Si3O10 and the transformation of β1-Li2ZnSiO4 to the more stable phase γ0- Li2ZnSiO4.

Abstract: The R2O-MO- Al2O3-SiO2 system glasses were prepared by conventional melt quenching technology. The composition mass fraction range of the glass is SiO2 (55%∼65%), MgO (0%∼15.2%), CaO (0%∼15.2%), SrO (0%∼15.2%), BaO (0%∼15.2%), Na2O (0%∼15.6%), K2O (0%∼15.6%). The relationship between the composition and the thermal expansion coefficient of the glass was investigated by comparing the thermal expansion coefficients of the glasses with different chemical composition. The results show that the thermal expansion coefficient of the glass increases sharply with the increase of alkali-metal oxide content and when K+, Na+ and Li+ exist simultaneously in the structure of the glass, the complex “mixed alkali effect” can be observed from the composition–thermal expansion coefficient curve. When introducing different kind but same quantity alkaline-earth metal oxide, the thermal expansion coefficient of the glasses increased obviously with the rising of the radius of alkaline-earth metal ions but the “mixed alkali effects” can also be observed for the glasses containing a few kinds of alkaline-earth metal oxides.

Abstract: Glasses in the Bi2O3-B2O3-BaO-ZnO system were prepared using the normal melt quenching technology. The structure of the glasses was analyzed by using of the infrared spectra within the range 2000∼400cm-1. The relation among the properties such as density (D), thermal expansion coefficient (α) and transition temperature (Tg), Bi2O3 introducing content and structure of the glass have been discussed.

Abstract: Based on the results in glass scientific research fields such as the National Natural Science Foundation project—forming and structure of heavy metal oxide glass, national defense new material projects and various other research projects, the new achievement and the present progress on the investigation in non-crystalline science exploration and the development for new kinds of glass materials in the school of Materials Science and Engineering of Central South University are briefly introduced in this paper.