Low‐Temperature Sintering and Microwave Dielectric Properties of Zinc Metatitanate‐Rutile Mixtures Using Boron

Abstract

Mixtures of zinc metatitanate and rutile (ZnTiO 3 + x TiO 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.