Crystallization Ability Of Glass Research Articles

Crystallization ability of glasses based on slags from the joint smelting of silicate nickel and copper pyrite ores

Crystallization ability of glasses based on slags from the joint smelting of silicate nickel and copper pyrite ores

Crystallization behavior and properties of quartz glass-ceramics synthesized from desert sand

Quartz glass-ceramics were synthesized with desert sand as the main raw material. The effects of pretreatment technology of desert sand and various cations on the glass stability (GS) parameters (KH, KLL,KW, KZW, KLX), crystallization kinetic parameters (crystallization activation energy (Ec), reaction rate (k), the effective frequency factor(ν) and the Avrami parameter (n)), phase transition, microstructure and properties of glass-ceramics were investigated. The results show that the chemical composition of desert sand is greatly changed by sieving and magnetic separation, and the glass stability, phase transition and crystallization ability of glass are controlled by the mixed mobile ion effect (MMIE), in which the ionic field intensity determined by ionic valence and radius plays a major role. Finally, the crystallization of glass is dominated by the surface crystallization mechanism, and the obtained glass-ceramics mainly consist of α-quartz, β-cristobalite and glass phases, which have excellent comprehensive properties.

ZrO2-doped transparent glass-ceramics embedding ZnO nano-crystalline with enhanced defect emission for potential yellow-light emitter applications

ZrO 2 -doped transparent silicate glasses and glass-ceramics embedding ZnO nano-crystallines were synthesized. The effects of ZrO 2 addition on the structure and optical properties of glass-ceramics were studied by DSC, XRD, SEM, IR, and PL spectra. The DSC results show that the crystallization ability of glass enhances with the addition of ZrO 2 . All the glass-ceramics after being heat-treated at 730 °C for 8 min can maintain a high transmittance in the visible range (>80%). With the increase of ZrO 2 content, the grain size of ZnO nano-crystallines shows a tendency of decline, while the bandgap and the defect-related emission (580 nm) intensity attributed to ZnO is enhanced. When the ZrO 2 -doping content is 2.5 mol%, the yellow emission (580 nm) intensity of ZnO crystals reaches the highest under excitation at 345 nm, which is 21 folds higher than that of ZrO 2 -free glass-ceramics. These results imply that the glass-ceramics embedding ZnO nano-crystallines doped with ZrO 2 would be a prospective candidate for yellow-light emitters.

Composition and synthesis development of building glass on the basis of non-standard raw materials

Colorless building glass on the basis of non-standard raw materials with the use of discolourers-cerium oxide and potassium nitrate-was synthesized. The regularities of the cerium oxide addition effect on the light transmittance of the glasses are shown when the proportion of Na2O is replaced by K2O. The results of ORP and iron oxide equilibrium investigation in glasses, improvement of light transmission by means of correction of ORP glass are presented. The physical and chemical properties of glasses are measured: thermal coefficient of linear expansion (TCLE), water resistance and crystallization ability of glasses. The recommended composition of a building glass on the basis of non-standard raw materials is presented.

Structure of glass near eutectics of phase diagrams on the example of the barium-borate system according to the DTA data

For the quantitative estimation of the crystallization ability of glass according to the thermal analysis data, the coefficient of the tendency to crystallization has been introduced Kcr, where the drawbacks of the well-known Hruby’s coefficient were eliminated. The opportunities of Kcr were demonstrated on the example of the glasses of system BaO-B2O3 in the composition range of 16–37 mol % BaO and the concentration dependence of Kcr has been plotted individually for powders and monoliths. It has been shown that the crystallization ability of the glass powders weakly depends on their composition, while for the monolithic glasses with a flame-polished surface it is exceptionally sensitive to the proximity of special points in phase diagrams, namely, stoichiometries and eutectics.

Synthesis and investigation of Ag-Cs-X (X = I, Br, Cl) glasses doped with Er3+

The glass formation and crystallization of ErI3-doped melts in the Ag-Cs-Pb-X (X = I, Br, Cl) are investigated in the section corresponding to the cation ratio Ag: Cs: Pb = 59: 39: 2 with ErI3 contents of 0.2–7.5 mol %. The glass transition, crystallization, and melting temperatures are determined for a number of compositions. The primary crystalline phases that precipitate from melts upon crystallization are identified. It is demonstrated that the iodide, bromide, and chloride glasses containing up to 0.5 mol % ErI3 have the lowest crystallization ability. An increase in the ErI3 content leads to the precipitation of unidentified erbium-containing phases from melts upon cooling and to an increase in the crystallization ability of glasses. The spectral and luminescence properties of the glass of the composition 52Ag · 17AgCl · 39CsBr · 2PbCl2 + 0.5 mol % ErI3 are studied in the range of the 4 I 13/2 → 4 I 15/2 transition of the Er3+ ion. It is found that the lifetime of the 4 I 13/2 → 4 I 15/2 level of the Er3+ ion is equal to 10 ms.

Influence of the composition of high-lead phosphate glasses on the location of the UV transmission edge and technological quality

This paper reports on the results of an investigation into the influence of the purity of the initial materials used for preparing vitreous lead metaphosphate, the acidity of the phosphate matrix, and the contents of additives of Group I–III and V elements and the second glass-former on the location of the UV transmission edge of simple binary and ternary lead phosphate glasses. It is shown that, even for a binary glass of the composition (mol %) 50PbO · 50P2O5, the location of the UV transmission edge can be shifted by ∼50 nm on the wavelength scale depending on the purity of the initial reactants. The shift of the UV transmission edge toward the UV spectral range for ternary glasses containing no variable-valence elements other than lead is considerably larger than that for the high-lead phosphate glass of the previously proposed composition involving antimony, niobium, and cerium oxides. It is established that the addition of niobium oxide Nb2O5 to lead phosphate glasses brings about a red shift of the UV transmission edge and a change in the crystallization ability of the glasses. Niobium oxide at a content up to 1.5 mol % increases the crystallization ability of the glass, whereas a change in the niobium oxide content from 1.5 to 3.1 mol % results in a decrease in the crystallization ability. It is demonstrated that the crystallization ability of high-lead phosphate glasses increases at a boron oxide content higher than 5 mol %.

Thermal analysis of mechanochemically activated glass

Thermal analysis (TG, DTG, DTA, DSC) has been used to study the influence of mechanochemical activation of glass making batch on its melting and obtained glass crystallization. It revealed, that long time (12 h) mechanical treatment accelerates the glass batch melting and also improving network homogeneity influence the internal structure of the obtained glass. Refinement of the glass, at the beginning reduces temperature and increases degree of crystallization as a result of nucleating action of the increasing surface area of grains. However long time activation lowers the crystallization ability of glass and increases crystallization temperature. This is attributed to the deformation of the structure surface layer and surface energy increase, hampering the crystals nuclei formation.