Authors: T. Toya, Yoshikazu Kameshima, Atsuo Yasumori, Kiyoshi Okada
1843
Authors: Viliam Pavlík, Eugen Jóna, Martina Sapietová, Soňa Šnircová
Abstract: The glasses with composition of Li2O . 2 SiO2 . n ZrO2 . n TiO2 (where n = 0; 0.015;
0.031; 0.050; 0.075; 0.1; 0.15; 0.2) were prepared and the relationship between structural and
selected parameters of thermal stability vs. crystallization has been studied by differential thermal
analysis. Structural analysis was provided by X–ray diffraction. The order of thermal stability vs.
crystallization representing of activation energy of studied glass systems which increase with higher
addition both oxides. The same order was obtained from the values of XRD. On the comparison the
glasses with zero addition titanium dioxide their activation energy was much higher.
399
Authors: Feng Zhou, Ying Qing Fu, Kai Ming Liang
Abstract: The crystallization behavior and microstructure of Li+-doped TiO2 thin films prepared by sol-gel dip coating were investigated by means of differential themal analysis (DTA), X-ray diffraction (XRD) and scanning electron microscopy (SEM). The crystallization apparent activation energy (E) both in the absence and in the presence of Li+ ion was also measured with Kissinger method. As a result the E values of Li+-doped TiO2 thin film were decreased, thus the crystallization of non-crystalline to anatase and antase to rutile was promoted.
750
Authors: Sang Hyeok Im, Nam Jin Kim, Dong Hwan Kim, Jae Young Kweon, Dong Keon Koo, Tae Hee Kim, Seong Hyeon Heo, Duck Ki Yoon, Bong Ki Ryu
Abstract: The study investigated the crystallization and sintering behavior in Li2O-Al2O3-SiO2 (LAS) glass powder. The sintered sample was produced with a glass particle (Φ=44㎛). The relative density and transmittance of the sintered samples showed the highest value at the temperature of 650°C. In the higher temperature than 650°C, the crystal growth occurred to decrease the densification of Li2O-Al2O3-SiO2 (LAS) glass powder. Main crystalline phase was β-spodumene in the glass powder. From the non-isothermal differential thermal analysis, the crystallization of the particles (Φ=44㎛) was observed at 640~684°C with respect to the heating rate. The activation energy of crystallization (EC) and Avrami constant (n) calculated by Kissinger and Ozawa equations indicated that the surface and the bulk crystallization occurred simultaneously in the glass. The optimum sintering condition of this glass powder was 650°C without crystal growth of β-spodumene, although a nucleation or nano-crystal growth occurred.
753
Authors: Shu Jiang Liu, Yan Fei Zhang
Abstract: Transparent phosphosilicate glass-ceramics were prepared by heating the spontaneously crystallized precursor glasses in which crystals have formed during cooling of the melts. And the effects of compositional variation on the crystalline phases, degree of crystallization and transparency were investigated by using X-ray diffraction (XRD), differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). It is found that Mg2+ tends to exist in silicate-rich phase rather than phosphate-rich phase, such MgO is more beneficial to the transparency of phosphosilicate glass-ceremics compared to CaO. In addition, the substitution of P2O5 for SiO2 enhances the tendency of phase separation, and hence the precipitation of Na2MgSiO4 crystals for the precursor glasses as well as glass-ceramics with good transparency.
1096
