Articles written in Bulletin of Materials Science
Volume 8 Issue 5 December 1986 pp 557-565
Glass ceramics prepared by controlled crystallization of glasses produce fine dispersion of crystallites in a glassy matrix. Glasses containing a mjor portion of constituents of a ferroelectric phase produce crystallites of ferroelectric phase in glass through a suitable heat treatment. The amount of network former in the initial glass has a profound influence on its crystallization behaviour and microstructure of the resulting ferroelectric glass ceramics. The value of dielectric constant and the nature of ferroelectric to paraelectric transition depend on the crystallite size and volume fraction of the ferroelectric phase. These glass ceramics are transparent for crystallite size less than 0·1
Volume 18 Issue 5 September 1995 pp 563-576
Complex immittance spectra of model equivalent circuits involving resistive and capacitive elements are calculated. A comparison of experimentally obtained complex immittance plots with these diagrams greatly facilitates the search for the most appropriate equivalent circuit representing the electrical properties of electronic ceramics.
Volume 18 Issue 5 September 1995 pp 577-585
65(SrO·TiO2)−35(2SiO2·B2O3) wt% glass was synthesized. Differential thermal analysis study shows one exothermic peak which shifts towards higher temperature with increasing heating rate. Glass ceramics prepared by controlled crystallization of strontium titanate borosilicate glass produce uniform distribution of crystallites in a glassy matrix. Attempt was made to crystallize strontium titanate phase in this glass ceramic. Different phases precipitated out during ceramization have been identified by X-ray diffraction. It appears that due to high reactivity of SrO with B2O3, strontium borate crystallizes as principal phase followed by TiO2 (rutile) and Sr3Ti2O7 phases. Dielectric constant of these glass ceramics was observed to be more or less temperature independent over wide range of temperatures with low values of dielectric constant and dissipation factor.
Volume 19 Issue 2 April 1996 pp 393-404
Glass of the nominal composition 64 wt%(SrO·TiO2)·35 wt%(2SiO2·B2O3)-1 wt%(CoO) was prepared. The glass samples were subjected to heat treatment at 900 and 950 C. The phase progression in these glass ceramics from X-ray diffraction studies shows the formation of Sr2B2O5 as primary crystalline phase followed by rutile (TiO2), Sr3Ti2O7, SrB2Si2O8 and Sr3B2SiO8 as secondary phases. The first DTA exothermic peak of glass corresponds to the crystallization of Sr2B2O5, rutile and Sr3Ti2O7 phase while second crystallization peak may be assigned to the formation of SrB2Si2O8 and Sr3B2SiO8 phases. From microstructure studies we find that strontium borate grows with larger grain size whereas the other phases like Sr3Ti2O7, TiO2 appear smaller in size. Cobalt oxide content in the strontium titanate borosilicate glass ceramic gives the thermal stability to dielectric behaviour and decreases the dielectric loss.
Volume 20 Issue 1 February 1997 pp 67-77
Glasses in the system (65 −
Volume 20 Issue 7 October 1997 pp 933-947
The electrical behaviour of valence-compensated ceramic system Ba1−
Volume 42 | Issue 5
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