Dielectric resonators with complex crystal structures in the La2O3–Al2O3–TiO2 system for microwave applications

Abstract

LaTi 2 Al 9 O 19 and La 3 Ti 5 Al 15 O 37 ceramics in the La 2 O 3 -Al 2 O 3 -TiO 2 system have been prepared by conventional solid state ceramic route. The structure and microstructure of the compositions have been studied using powder X-ray diffraction and scanning electron microscopic techniques. Laser Raman studies have been employed to understand the complex crystal structure of these compositions in molecular level. The microwave dielectric properties of the sintered ceramic compacts were measured by Hakki and Colemann post resonator and TE 01d cavity techniques using a vector network analyzer. LaTi 2 Al 9 O 19 and La 3 Ti 5 Al 15 O 37 ceramics possess excellent microwave dielectric properties such as relatively high unloaded quality factors 7,762 and 7,415, low dielectric constant 15.7 and 22.1 and low temperature coefficient of resonant frequency values -22 and ?18.9 ppm/°C, respectively.

Plasma fluorination modified CaTiO3 for dielectric properties of PTFE-based composites

“…With the rapid development of microelectronic techniques for integration and functionalization, microwave dielectric materials are more urgently needed [1] . Polymeric ceramic composites not only combine the lightness, flexibility, and processability of the polymer with the dielectric characteristics of the ceramics but also achieve functional composite material with adjustable properties at a relatively lower cost [2] . However, the surface properties of ceramics and polymers are very different, which makes ceramic particles difficult to disperse in the polymer and easy to aggregate, resulting in poor compatibility between the two phases [3,4] .…”