GLASS CERAMICS OF b-SPODUMENE COMPOSITION
WITH CONTROLLED DIELECTRIC CONSTANT
E. I. Suzdal’tsev
Translated from Ogneupory i Tekhnicheskaya Keramika, No. 5, pp. 15 – 17, May, 2002.
A new class of heat-resistant, radio-transparent glass ceramic materials of b-spodumene composition is deve
loped. Modifying Li – aluminosilicate glasses with TiO
addition allows preparation of materials with con
trolled dielectric constant in the range of7–12units.
It has been reported earlier [1 – 5] that ceramic techno
logy for fabrication of glass ceramic has a number of advan-
tages over the traditional glass technology. The traditional
technology requires strict observance of the chemical com-
position of precursor glasses, which, in turn, places limita-
tions on the preparation of glass ceramic materials with a
given dielectric constant. Under modern conditions of the
frequent design modification of components and different re-
quirements placed on radio-engineering characteristics, the
use of traditional technologies becomes less effective in both
technical (development of new compositions, melting, crys-
tallization, etc.) and economical aspects.
It was shown in  that the dielectric constant as a func
tion of the material composition is best described by the
log e = c log e
+(1–c) log e
where e is the dielectric constant of the composite material;
is the dielectric constant of the material of addition; e
the dielectric constant of the material of the matrix; and c is
the volume concentration of the material of addition.
An analysis of TiO
-modified materials has shown that
the dielectric constant of these materials can effectively be
controlled by varying the concentration of TiO
(Fig. 1) on
condition that the material of addition does not react with the
material of the matrix and that the addition is uniformly dis
tributed over the composite’s bulk.
The data in Fig. 1 show that modifying a matrix of glass
ceramic material provides a way toward compositions whose
dielectric constant can be varied over a wide range.
In this work, a glass ceramic of lithium aluminosilicate
composition modified by TiO
in the solid-phase state was
The procedure was as follows. Granulated lithium alumi-
nosilicate glass (SiO
= 65%; Al
= 25%; Li
O = 4%; and
= 6%) was ground in water to yield a high-density sus-
pension (r = 1.97 – 2.05 g/cm
modifier was intro-
duced into the stabilized suspension at a concentration
needed for the required value of dielectric constant. The mix-
ture was thoroughly homogenized and then cast into gypsum
molds to prepare preforms with specified dimensions. The
Refractories and Industrial Ceramics Vol. 43, Nos.5–6, 2002
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Tekhnologiya Federal State Unitary Production and Research En
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TiO concentration, %
Fig. 1. Dielectric constant of ceramic materials plotted as a function
concentration: 1 ) quartz ceramic; 2 ) glass ceramic; 3 ) alu
minum oxide ceramic.