Mixtures of zinc metatitanate and rutile (ZnTiO 3 + xTiO 2 , where x = 0-0.5) have been prepared via the conventional mixed-oxide method. Centrifugal planetary milling with zirconia beads 1 mm in diameter produced very fine powders (mean particle size of 0.2 µm), which allowed the synthesis of ZnTiO 3 and sintering at temperatures <945°C, which is the decomposition temperature of ZnTiO 3 . Sintering of the mixtures was enhanced further by the addition of B 2 O 3 . Densities of >94% of the theoretical density have been attained for the specimens that were sintered at 875°C for 4 h with B 2 O 3 additions of <1 wt%. Microwave dielectric properties of the aforementioned compositions were as follows: dielectric constant of 29-31, normalized quality factor of 56000-69000 GHz, and a temperature coefficient of resonance frequency between −10 and +10 ppm/°C. Sintering was enhanced by the formation of a ZnO-B 2 O 3 liquid phase, which affected the microwave properties, because of variation in the phase composition.

A dielectric ceramic comprised of (Zn 1−x Mg x )TiO 3 (x = 0 to x = 0.5) with low sintering temperature and promising microwave properties was prepared by applying a semichemical synthesis route and a microbeads milling technique. X-ray diffractometry and thermal analyses results indicated that the phase stability region of the hexagonal (Zn,Mg)TiO 3 extended to higher temperatures as the amount of magnesium increased. The dielectric properties in this system exhibited a significant dependence on the sintering conditions, especially near the phase decomposition temperature. From 950°C, the temperature compensation characteristics occurred as the phase composition changed from hexagonal (Zn,Mg)TiO 3 to two phases: (Zn,Mg) 2 TiO 4 and rutile. The magnesium content for zero temperature coefficient ( f ) was ∼3 mol% at 950°C; however, f increased with the sintering temperatures because of the shift of the decomposition temperature.