Dielectric Properties of (1-x)La(Mg_0.5Sn_0.5)O₃-xCa_0.8Sr_0.2TiO₃ Ceramic System at Microwave Frequencies

Abstract

The microwave dielectric properties of (1-x)La(Mg_0.5Sn_0.5)O₃-xCa_0.8Sr_0.2TiO₃ ceramic system were investigated with a view to their exploitation for microwave devices. The diffraction peaks of (1-x)La(Mg_0.5Sn_0.5)O₃-xCa_0.8Sr_0.2TiO₃ ceramic system shifted to higher angles as x increased from 0.4 to 0.7. The X-ray diffraction patterns of the 0.4La(Mg_0.5Sn_0.5)O₃-0.6Ca_0.8Sr_0.2TiO₃ ceramics exhibited no significant variation of phase with sintering temperatures. The average grain size of the (1-x)La(Mg_0.5Sn_0.5)O₃-xCa_0.8Sr_0.2TiO₃ ceramic system decreased from 5.2 to 2.4 μm as x increased from 0.4 to 0.7, sintered at 1550°C for 4 h. The dielectric constant increased from 28.7 to 46.0 and the quality factor (Q × f) decreased from 35,800 to 6,600 GHz as x increased from 0.4 to 0.7, sintered at 1550°C for 4 h. The average value of temperature coefficient of resonant frequency (τ _f ) increased from −66 to +32 ppm/°C as the x increased from 0.4 to 0.7.

Keywords:

• (1-x)La(Mg_0.5Sn_0.5)O₃-xCa_0.8Sr_0.2TiO₃
• dielectric constant
• quality factor
• temperature coefficient of resonant frequency