Preparation And Characterization Of Rare Earth Doped Borate Transparent Glass-ceramics Materials

This text expatiates the optical transparency principles and the forming conditions of glass-ceramics. The factors affected the optical transmittances of glass-ceramics were discussed in the terms of compositions, structure, performance and processes. The origin and development, synthetic methods and applications of glass-ceramics were outlined, and the developing trend was forecasted as well.B2O3-Al2O3-SiO2(BAS) system transparent glass-ceramics were synthesized by the melting method and crystallization technique. The crystallization heat-treated schedules were based on DSCA results. The compositions and structure of crystal phases were determined on the base of XRD results. The transparent BAS glass s-ceramics with main crystal phase-2Al2O3·B2O3and minor crystal phase-(3-SiO2solid solutions, Al2O3·B2O3and9Al2O3·2SiO2were obtained, It was shown that the little change to the compositions influenced the crystal phases unmarkedly. The short-range structure of the transparent glass-ceramics was researched by XPS. The optical transmittances of the BAS glass-ceramics were measured by spectrophotometer. The influences of crystallization heat-treated schedules to the optical transmittance were discussed. The microstructure of the transparent BAS glass-ceramics was characterized by SEM, and the microstructure parameters were obtained by means of automatic image analysis technique.The microstructure was studied by stereology principles and method, and the relationship between the microstructure and the optical properties was explored. Transparent ZnO-B2O3-Al2O3-SiO2(ZBAS) system glass-ceramics were synthesized by the melting method and annealing technique. The crystallization heat-treated schedules were based on DSC results. The compositions and structure of crystal phases were determined on the base of XRD results. The transparent ZBAS glass-ceramics with main crystal phase-cubic gahnite ZnAl2O4at the same time, gahnite became to the minor crystal phase. The influences of crystallization heat-treated schedules to the optical transmittance were discussed. The microstructure of the transparent ZBAS system glass-ceramics was characterized by SEM, and the microstructure parameters were obtained by means of automatic image analysis technique. The microstructure was studied by stereology principles and method, and the relationship between the microstructure and the optical properties was explored. The optical transmittance decreased with the increasing of the three dimensional sphere diameters and the mean specific area of grains per volume. The optical transmittance increased with the enhancing of the mean three-dimensional free distance of grain boundaries and the mean specific area of single grain.BaO-B2O3-O2-Al2O3-SiO2system transparent glass-ceramics were synthesized by the melting method and annealing technique. The crystallization heat-treated schedules were based on DSC results. The compositions and structure of crystal phases were determined on the base of XRD results. The transparent glass-ceramics doped Nd3+with main crystal phase.Three main fluorescence bands centering at about890nm,1065nm and1330nm were observed, which were correspondent to the transitions of4F3/2â†'4I9/2,4F3/2â†'4I11/2and4F3/2â†'4I13/2, respectively. The fluorescent intensity increased markedly.which grain size was approaching to the wavelength of the visual light. Quenching disappeared after the precipitation of the B-spodumene.The precipitation of crystal phases from glass phase includes the nucleus forming and crystal growing dynamic processes. The mechanism of the crystal phase precipitation and growth in transparent glass-ceramics system was studied, and it was submitted to the function. The kinetics of crystal phase growth controlled by the diffusion in fractal structure was analyzed by fractal spectrum dimension. It was presented that the difference between the fractal kinetics and traditional kinetics, and the relationship between the reaction kinetics and fractal structure as well. The fractal spectrum dimension ds is1.2688calculated by fitting curve of experimental data.