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Abstract
The AC electrical data, measured in the frequency range 0.1 Hz-5 MHz, were used to study the electrical response of lithium barium titanium alumino borosilicate glass-ceramics containing strontium or magnesium. Complex plane plot from these electrical data for various glass ceramic samples reveal contributions from simultaneously operating polarization mechanisms to overall dielectric behaviour. The SrO/BaO or MgO/Al^sub 2^O^sub 3^ replacements resulted in the increase of the conductivity and dielectric constant of the corresponding glass-ceramic materials. The relationships between the crystalline phases formed and dielectric values of studied glass-ceramics are complicated. The complex impedance of the crystalline materials generally decreases with the addition of SrO instead of BaO and with increase of MgO at the expense of Al^sub 2^O^sub 3^. The obtained data were correlated to the internal microstructure, crystalline phases formed, glassy matrix and glass to crystal interface region. β-Spodumene together with varieties of Ba-containing phases [e. g. orthorhombic celsian--BaAl^sub 2^Si^sub 2^O^sub 8^, fresnoite--Ba^sub 2^(TiO)Si^sub 2^O^sub 7^], barium silicate Ba^sub 2^Si^sub 3^O^sub 8^, lithium borate--Li^sub 6^B^sub 4^O^sub 9^, lithium metasilicate--Li^sub 2^SiO^sub 3^ strontium titanate--SrTiO^sub 3^, and magnesium borate--MgB^sub 4^O^sub 7^ phases were mostly developed in the crystallized glasses. The microhardness characteristics of the crystalline glasses have been investigated by Knoop microhardness. The SrO/BaO or MgO/Al^sub 2^O^sub 3^ replacements resulted into decreasing the microhardness values. The obtained data of the glass-ceramic specimens were explained in relation to the crystalline phases, microstructure formed and the glassy matrix.[PUBLICATION ABSTRACT]