Kinds Of Glass Ceramics Research Articles

Optical temperature sensing behavior of Dy3+-doped transparent alkaline earth fluoride glass ceramics

Dy3+-doped transparent BaF2, CaF2, and SrF2 glass ceramics were fabricated, respectively, by a melt-quenching method, and their structures of resulting alkaline earth fluoride glass ceramics are studied by the X-ray diffraction and transmission electron microscopy. Temperature-dependent spectra, thermal quenching ratios, sensitivity are studied systematically in three kinds of glass ceramics. Using fluorescence intensity ratio method, the 4I15/2 and 4F9/2 of Dy3+ ions are verified as thermally coupled energy levels. A new fitting method to establish the relation between fluorescence intensity ratios and temperature has been developed to reduce the error value of sensitivity. It is found that the values of sensor sensitivity SR are dependent on host types, and the maximum SR = 0.00032 K−1 is obtained at T = 576.5 K in Dy3+-doped transparent SrF2 glass ceramics.

Infrared-to-Visible Up-conversion in Er-Pr-Yb Triply Doped Oxyfluoride Glass Ceramics

We synthesized Er3+-Yb3+, Pr3+-Yb3+, and Er3+-Pr3+-Yb3+-doped oxyfluoride glass ceramics containing CaF2 nanocrystals by proper thermal treatments. Spectral characteristics of down- and up-converted emissions in three kinds of glass ceramics under 365-nm and 980-nm excitations were compared and explained by cross relaxations, excited-state absorptions, and energy-transfer processes between different ions. The huge reduction of up-conversion emission in the triply doped glass ceramics under 980-nm excitation compared to the Er3+-Yb3+ codoped one was explained by the split pump power and the direct energy transfer from Er3+ to Pr3+ ions. Increasing Yb3+ concentration from 2% to 10% in the triply doped glass ceramics showed more than quadratic enhancement of the absorbed power, and we explained it by the enhanced energy-transfer efficiency from Yb3+ to Er3+ ions. We also observed enhanced up-converted emissions of Er3+ and Pr3+ ions in three kinds of glass ceramics under simultaneous excitation at 980 nm and 1550 nm, and suggested detailed up-conversion mechanisms.

The crystallization and microstructure evolution of lithium disilicate-based glass-ceramic

In this work, transformation of crystalline phases and development of microstructure of two kinds of glass-ceramics, SiO2–Li2O–P2O5 and SiO2–Li2O–K2O–Al2O3–ZrO2–P2O5, have been studied by X-ray diffraction and scanning electron microscopy analysis.In the former glass, a small amount of spherical Li2Si2O5 crystals precipitated at the usual nucleation temperature, which changed little in size and packing density with the increase of the temperature. These spherical Li2Si2O5 also have no effect on the volume crystallization of residual glass or the morphology of subsequently formed plate-like Li2Si2O5 crystals. In the latter glass, Li2SiO3 crystallized first and then decomposed at higher temperature, forming two kinds of Li2Si2O5 crystals with different morphologies. The interlocked rod-like shaped Li2Si2O5 crystals were resulted from interaction of Li+ ions and SiO2-rich glassy phase and oriented crystal bundles of Li2Si2O5 were formed from rearrangement of a silicate framework in Li2SiO3.

Evaluation of Subcritical Crack Growth in Glass Ceramics. Examination by Double Torsion Technique.

The lifetime prediction of ceramics has been discussed on the basis of the relationship between the stress intensity facter (K1) and crack velocity (V). In the present work, the effect of environment on this relationship was studied for two kinds of glass ceramics with different grain sizes. The load relaxation method and controlled load method, which are double torsion (DT) techniques, were used for the determination of the K1-V characteristics under different environments of air and ionexchanged water. The controlled load method, which is simple and reliable, has been proposed by the authors. We also examined the possibility of failure prediction using acoustic emission (AE). As a result, it was found that at high K1, V is enhanced by diffusion of corrosive species to crack tips and is also dependent on the amount of water. Crack growth resistance significantly increases with increasing grain size. Also, the AE event rate is quantitatively related to V.

Effect of MgO Addition on the Bondability and Interfacial Reaction between Dielectric and Glass-Ceramics for the Fabrication of Multi-Component Ceramic Substrates

Abstract Bondability and interfacial reaction between dielectric and insulator layers have been examined to obtain a basic understanding of bonding mechanisms. Lead-containing complex perovskite was used as a dielectric material. Two kinds of glass-ceramics were used as insulator material; lead borosilicate glass containing Al2O 3 (insulator A) and the same containing Al2O3 and MgO (insulator B). Dielectric and insulator layers did not bond when insulator A was used. When insulator B was used, however, strong bonding was achieved between the two layers by firing the powder compacts at temperatures between 800° and 1000°C. Addition of MgO to lead borosilicate glass increased the thermal expansion coefficient to that of the dielectric and enhanced the formation of reaction layers, resulting in good bonding. Two reaction layers were identified. The main reaction products were enstatite and bredigite for one layer contacting the dielectric, and enstatite and a compound with the same diffraction pattern as tha...