Design considerations of the lead-based glass composition was broadened beyond the two known criteria of matched index of refraction and thermal coefficient of expansion to include previous studies of thick film materials. Five criteria for the glass-design composition were used: matched index of refraction and thermal coefficient of expansion, components (MgO and Al₂O₃) to slow down dissolution of spinel (MgAl₂O₄) into the glass, non-crystallizing glass in a broad temperature range and glass with good chemical durability. Synthesis and characterization of glass, glass paste preparation and its application to spinel substrates to form coating and bonding and optical characterizations in the UV, VIS and IR of coated, uncoated, and bonded spinel substrates of two commercial sources are described. Enhancement of transmittance exceeding the theoretical value of polished spinel was found for the first time when glass coating was applied to a ground face of semi-polished spinel.

Barium silicates have been investigated as high-expansion components of solid oxide fuel cells (SOFCs) and, therefore, their synthesis and expansion have been the subject of intensive research in recent years. In this article, we briefly present a new process to make glass–crystalline composites, as well as two novel findings related to a synthesis route of sanbornite (BaSi₂O₅) and the fast in situ formation of a high-expansion sanbornite composite from a Pyrex-type glass powder. The low-temperature synthesis, composition, and expansion of one type of novel glass composite are described. The composites are made by the reaction of BaCO₃ and Pyrex-type powders at 850–950 °C for a short time of one hour. The composites are well sintered and hard, and their linear coefficient of thermal expansion is about 12.3 × 10⁻⁶ C⁻¹. The crystalline-phase formation, dilatometer measurements, SEM data, and possible applications of the composites are presented and discussed.

A mixture of barium carbonate and Pyrex-type powders was heat treated at 500°C-950°C temperature range, for 2 hours at each temperature. The course of the reaction was studied by XRD and weight loss analysis. Reaction of barium carbonate with the Pyrex-type glass was detected at 600°C by weight loss analysis. XRD shows formation of various barium silicates starting at 650°C. At high temperature ,850-950°C, only one crystalline phase, sanbornite, was detected. Silica phase related to quartz starts to separate from the Pyrex-type glass at 650-800°C. Another phase of silica, cristobalite, was detected at 750°C only. The separated silica phase is very reactive with barium carbonate, yielding various silicates well below the decomposition temperature of barium carbonate.