Showing papers by "E. J. Friebele published in 1990"
TL;DR: In this article, the limits of glass formation at 1600°C were found to expand as silica is added to calcium aluminate base compositions, keeping the CaO/Al2O3 ratio constant.
Abstract: Calcium aluminosilicate glasses with small percentages of silica have been prepared. The limits of glass formation at 1600°C were found to expand as silica is added to calcium aluminate base compositions. The behavior of such physical properties as glass transition temperature and transition range viscosity has indicated that the structural role of silica changes as its concentrations is increased, keeping the CaO/Al2O3 ratio constant.
99 citations
01 Oct 1990
TL;DR: In this paper, the authors used TEM measurements to characterize the microcrystals using TEM when the heat-treatment conditions are varied, and found that the ratio of Cu2 to Cu'in the glass at various compositions before heat treatment was unknown.
Abstract: Quantum confinement effects of semiconductor microcrystallites (CuC1) embedded in a glassy ( aluminoborosilicate) matrix are of current interest due to their exceptional nonlinear optical properties. Theprecipitation of microcrystals occurs upon heat-treatment of a glass in a supersaturated solution. The timeand/or temperature of heat-treatment and the degree of supersaturation of the solution determines the size ofthe microcrystals. This paper characterizes the microcrystals using TEM when the heat-treatment conditions arevaried. Room temperature ESR measurements were performed in order to determine the ratio of Cu2 to Cu'in the glass at various compositions before heat-treatment. Low temperature optical absorption data werejobtained to study the quantum confinement and the effect of varying the microcrystal size.I. IntroductionWithin the last ten years the optical properties of semiconductor microcrystals embedded in a glassy matrix have attracted considerable interest.19 Much is known about the large nonlinearities of thin film quantum-
4 citations
01 Oct 1990
TL;DR: In this paper, the effect of small silica additions on such properties as viscosity and crystallization tendency has been combined with a study of such optical properties as infrared cut-off and UVVis-NIR spectroscopy.
Abstract: Calcium aluminate glasses are transparent to a longer wavelength than silicate gI asses. However it is well known that they are difficult to form into conventional optics due to their high tendency to crystallize. To increase the understanding of aluminate glasses a study of the effect of small silica additions on such properties as viscosity and crystallization tendency has been combined with a study of such optical properties as infrared cut-off and UVVis-NIR spectroscopy. 1.
4 citations