Effect of synthesis and sintering technique on the long-range 1:3 cation ordering and microwave dielectric loss of Li2ZnTi3O8 ceramics

Abstract

This study first reports the synthesis of Li2ZnTi3O8 (LZTO) system by microwave (MW) and conventional (CS) sintering techniques. The effects of both synthesis and sintering technique on the structure, degree of ordering and microwave dielectric properties of LZTO ceramics were investigated. Based on XRD data analysis, a single phase Li2ZnTi3O8 is obtained for both synthesis techniques. However, fully ordered LZTO system can only be obtained by the CS method. All the samples display nearly non-homogenous grain growth with an average grain size of 7 μm (MW sintering) and 38 μm (CS sintering), respectively. The calculated activation energy of the grain growth for LZTO ceramics was reduced from 329 kJ/mol (MW process) to 233 kJ/mol (CS process). The LZTO ceramics finally densified at 1075 °C display dielectric constants of εrCS = 25.26 and εrMW = 25.65, temperature coefficient of resonant frequencies of τfCS = -13.6 ppm/°C and τfMW = -12.0 ppm/°C and Q×f values of 76,000 GHz and 65,000 GHz for CS and MW samples, respectively. It is clear, therefore, that the synthesis and thermodynamics (sintering) can both play an important role in shaping the physical properties of LZTO materials.