| The majority of traditional transparent glass-ceramics have nano-size crystals and small to moderate crystallized volume fraction, usually between 3% and 70%, which results in obvious different physic-chemical properties between the glass-ceramics and the crystals or the transparent ceramics. In this paper, preparation method of rare earth ions doped transparent glass-ceramics with high crystallinity and the relationship between crystal type, crystal content, grain size, glass phase and luminescent properties were studied. The aim is to explore the possibility of highly crystalline transparent glass-ceramics substituting for crystals or transparent ceramics. Obviously, there are very important research value and actual significance.In this paper, the transparent Nd2O3 doped Na2O-CaO-SiO2 (NCS) glass-ceramics with high crystallinity were prepared by conventional melt-quenching method and optimized heat treating regime. Nucleation and crystallization conditions of precursor glass were determined by DSC The crystal phase, crystallite size, morphology and transparency were examined by XRD, IR, and SEM. The results show that the compositions of the crystals were close to Na6Ca3Si6O18.when NCS glass was heat-treated under different conditions. The spherical crystals with grain size of about 1～2μm were obtained by nucleation at 630℃for 10 h and crystallization at 800℃for 1 h. The crystallinity reached up to 79.86% and the transmittance was 68.8% atλ=710nm for 3mm thick sample. By prolonging the thermal treatment time, the crystallization was almost complete with grain size of about 250μm, and the transmittance of 3mm thick sample still remained 65.5% atλ=710nm. A continuous variation of chemical compositions in both glass and crystal compositions was observed during crystallization. The optical absorption and emission intensities of Nd3+-doped transparent glass-ceramics with high crystallinity in NCS system were studied. Judd-Ofelt theory is performed to evaluate the radiative transition probability as well as quality factor, branching ratio and emission cross section. The maximum values ofΩ2 and emission cross section (4F3/2â†'4I11/2) of NCS are obtained after nucleating at 630℃for 10 h. The quality factor increases with increasing crystallinity, while branching ratio for 4F3/2â†'4I11/2 is opposite. The results show that transparent glass-ceramic with high crystallinity is a potential laser host for 1.06μm emission.The transparent glass Gd2SiO5(GSO) system was successfully prepared, which mainly contains Gd2O3-SiO2-B2O3 compound, and the weight percentage of Gd2O3 up to 75.88%. The Ce3+ ions were successlly added in glass GSO system, color of glass deepened after increasing Ce2O3 content, which changes from light-yellow, lemon to amber colour, and the color of glass reduced with the increase of the amount of ultrafine Sb2O3 added. In this paper, crystallization heat treating technology of GSO glass made explored, sample became translucent but no crystals appeared when was heated at 950℃after nucleating at 800℃for 10 h, and the glass was total devitrification when the temperature rose continually to 975℃. The precipitated crystals were close to Gd4.67(SiO4)3O which belongs to hexagonal crystal system, the cell parameters obtained by Rietveld refinement of X-ray diffraction data are a=b=0.927nm, c=0.685, showing the size of grain become smaller. Consistent with the requirement of precipitated micro-crystal and Gd2SiO5 crystal chemical composition should be similar or identical. |
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