Development of temperature-stable thick-film dielectrics. III. Role of glass on the microstructure evolution of a thick-film dielectric

For pt.I see ibid., vol.12, p.798-808 (1989). Glass phase plays an important role in the characteristics of thick-film microelectronics. A dielectric system in BaTiO/sub 3/ and SrTiO/sub 3/ containing PbO, B/sub 2/O/sub 3/, SiO/sub 2/, and Al/sub 2/O/sub 3/ glass constituents is investigated. Microstructure evolution and phase distribution after thermal aging are studied with the aid of electron microscope and X-ray diffractometer. It is observed that the phases in 40 vol.% BaTiO/sub 3/-25 vol.% SrTiO/sub 3/-35 vol.% glass thick-film dielectric are not altered after 500 degrees C aging for 480 h. The variation in surface morphology after aging is attributed to the precipitation of heavy metal component from the glass which acts as a diffusion species and then dissolves the crystalline phase during firing. The presence of glass in the dielectric enhances the formation of solid solution (Ba/sub /xSr/sub 1-/x)TiO/sub 3/ and results in the broadening of the Curie peak.>