Thermal properties of calcium aluminate xCaO-(1-x)Al2O3 glasses

Thermal studies of xCaO-(1-x)Al2O3 (x=0·4, 0·45, 0·5, 0·55, 0·632, 0·7, 0·75 and 0·8) glasses have been performed using differential scanning calorimetry (DSC) at different heating rates. Glass transition temperatures and crystallization temperatures were evaluated from DSC scans and are found to increase with heating rate. The glass transition temperature increases with increasing CaO content exhibiting a maximum at around 0·632 CaO mole fraction, which corresponds to the eutectic composition in the phase diagram of the CaO-Al2O3 binary system. Further increases of the modifier content leads to monotonic decrease of Tg for all heating rates. The apparent activation energy for glass transition was calculated using the Kissinger method, while the activation energy for crystallization was calculated using Ozawa and Matusita equations. The results of both methods concerning the activation energy of crystallization were compared and discussed. The Saad-Poulain and Hruby parameters, which reflect the glass stability, are estimated for all compositions studied in the binary glass system. Both parameters fail to explain the glass forming ability of these glasses. The results are correlated to the structural modifications taking place in this compositional range.status: publishe

Photosensitivity in glasses

A photosensitive glass containing a small amount of a photosensitive metal such as Au, Ag, or Cu, and a sensitizer of CeO2, is expressed a function of the redox reaction induced by the irradiation of ultraviolet light. In particular, a photosensitive glass is an indispensable material in the photolithography technique, which is valuable in the microprocessing of glass substrates. Here we aim to discuss the photosensitivity of glass from the perspectives of photochemical, photophysical, and photothermal mechanisms. In particular, from three different points of view (photothermal, photochemical, and photophysical interactions), various intriguing phenomena induced by ultrashort pulse lasers are addressed. Furthermore, a new type of photosensitivity exhibiting nonreciprocal characteristics is also discussed