• Journal of Korean Ophthalmic Optics Society
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• v.7 no.2
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• pp.27-31
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• 2002

Quarternary $Li_2O-B_2O_3-Al_2O_3-SiO_2$ glasses were fabricated by the function of $R({\equiv}Li_2Omole%/B_2O_3mole%)$ and $K({\equiv}(Al_2O_3mole%+SiO_2mole%/B_2O_3mole%)$. The structures of these glasses were investigated through refractive index and Vicker's hardness. The refractive index increased as the increase of the polarizability in the glass network. In the region of low $Li_2O$ content, the refractive index increased due to the increase of the polarizability in the glass network but, in the region of high $Li_2O$ content, the rate of increase of the refractive index decreased due to the increase of the molar volume caused by the formation of $BO_3{^-}$ units with relatively high molar volume. And, the refractive index decreased as the increase of $Al_2O_3+SiO_2$ content with the molar volume in the glass network. The increase and decrease of vicker's hardness values for those glasses depended on the fraction of tetrahedral $BO_4$ units and it of triangle $BO_3{^-}$ units with non-bridging oxygen, respectively.

• Journal of Ceramic Processing Research
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• v.20 no.1
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• pp.63-68
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• 2019

We investigated the effects of Al2O3 addition on (1-x)Li2B4O7-xAl2O3 (LBAO; x = 0, 0.005, 0.01, 0.05, 0.07, and 0.1) glasses. The glasses were synthesized by a conventional melt-quench method. Structural transformations of the LBAO glasses were assessed via X-ray diffraction analysis. Estimations of ΔT, KGS = (Tc-Tg)/(Tm-Tc), activation energy, and the Avrami parameter were performed using differential thermal analysis and differential scanning calorimetry. An interpretation of non-isothermal kinetics of the crystallization process is presented using the modified Ozawa equation. The activation energy E increased from 3.3 to 3.5 eV for the LBAO (x < 0.01) glasses whereas those of the LBAO (x > 0.05) glasses slightly increased from 3.75 to 4.05 eV. The exponent n was estimated to be 3.9 ± 0.1 for the LBAO (x < 0.01) glasses and 3.2 ± 0.02 for the LBAO (x > 0.05) glasses. Microstructural characterization of the glassy and crystalline phases using atomic force microscopy was investigated. The effects of Al2O3 on the LBAO glasses include a decreased nucleation rate in the crystallization process and a significantly reduced crystal size.

• Journal of the Korean Chemical Society
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• v.34 no.1
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• pp.63-68
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• 1990

The chemical ingredients such as $SiO_2,\;Al_2O_3,\;MgO,\;Fe_2O_3,\;CaO$ and $TiO_2$in silica minerals were determined by X-ray fluorescence spectrometry using a matrix correction method. The synthesized standards mixed with reagent grade oxides and the sample were diluted by fusing with 16 times $Li_2B_4O_7$. The matrix effects correlated among the ingredients were corrected by the empirical coefficient method based on the Lucas-Tooth and Pyne model. The analytical results showed relatively good agreement between the different sets of coefficients but were improved with increasing the number of standard. The accuracy of this method was also examined with the standard reference material of NIST.

• Analytical Science and Technology
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• v.9 no.4
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• pp.382-391
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• 1996

In this study, 12 different chemical species of fine ceramic($BaTiO_3$) were synthesized as the standard materials for the fast and accurate measurements of X-ray fluorescence spectrometry. Samples were diluted to sixteen times with the filling compound ($Li_2B_4O_7+LiBO_2$) in order to remove the matrix effect, and to get the convenient storage and homogeneity of ingredients. The matrix effects among the ingredients were corrected by the empirical coefficient method based on the Lucas-Tooth and Price model. The standard curve on 12 standard materials containing 15 elements were obtained by using X-ray fluorescence spectrometry at three different laboratories. The correlation factors of BaO, PbO, SrO, $Fe_2O_3$, $La_2O_3$, $SnO_2$, ZnO, $ZrO_2$, CaO indicated the relati vely good agreement over 0.995 among the three different laboratories. $SiO_2$ and $Al_2O_3$ showed the poor linearity because of their low fluorescence intensities.