Porous optical composites

Abstract

ABSTRACT Previous studies have shown that sol-gel matrices are excellent low temperature hosts forvarious optically-active materials, both organic and inorganic. Optical properties of thesecomposites depend upon such factors as the structure of the matrix and size, shape, and degreeof dispersion of the optically-active phase. We discuss factors that control the shrinkage andclarity of silicate aerogel host matrices and report on novel composites in which the opticalproperties are controlled by solid-vapor and/or solid-liquid reactions within the host matrix.1. INTRODUCTIONThe radioluminescent light (RL) program at Sandia National Laboratories and E.G.& G. MoundApplied Technologies is conducting research to improve radioactively-powered light sources andto develop power supplies based on this technology. Current studies have focused on developinga volumetric light source powered by radiation. The volumetric light is intended to improvelight output over current technology while enhancing safety. We report on the results of anoptically active aerogel/phosphor composite in which light output is controlled by aerogelproperties, concentration and dispersion of the phosphor, and source of excitation radiation.Aerogel/phosphor composites are prepared by suspending a commercial phosphor powder in aso!. After gelation, aging, and supercritical solvent extraction, a beta source is placed inproximity to the phosphor grains through the aerogel pores. The beta particles excite thephosphor and cause it to luminesce. This light source should have a higher light output thanconventional surface RL lights because light is emitted not only from the aerogel surface butalso from within some portion of the aerogel volume. Thus, it should have some of theintensity-additive properties of a true volumetric light source.Uses for self-powered radioluminescent lights include emergency lighting for aircraft,submarines, and ships, instrumentation panel and docking lights for space applications, lightingwhere electrical power is difficult or impossible such as remote runway lighting, and low energyradiation detection (e.g., T2 detector).This work is supported by the US DOE under contracts #DE-ACO4-76DP00789 and #DE-