Of Mn And Mo On The Microwave Dielectric Ceramics 0.24znnb <sub> 2 </ Sub> O <sub> 6 </ Sub>-0.76zrti <sub> 2 </ Sub> O <sub> 6 </ Sub> Performance The Impact

Microwave dielectric ceramics xZnNb₂O₆-(1-x)ZrTi₂O₆ (x=0.24) exhibited good dielectric properties:ε_r= 45, Q×f= 27660 GHz andτ_f= 0.2 ppm/℃.The effects of Mn and Mo additives on the microstructure and microwave dielectric properties in 0.24ZnNb₂O₆ - 0.76ZrTi₂O₆ (0.24ZN-0.76ZT) composition were investigated.Different atmospheres, air and oxygen, were used in the sintering process for each composition with varying additive content up to 0.5 wt%. The sintering temperature and time were 1280℃and 4 hours respectively. The microstructure, defect structure and sintering behaviour were investigated as a function of additive content. X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Wavelength Dispersive Spectroscopy (WDS) were employed in the process. In Mn doped samples, the density, average grain size, relative permittivity and temperature coefficient of frequency were not sensitive to the additive content. The Q×f value, however, was significantly dependent on additive content. Doping with low-level additive and sintering in oxygen atmosphere showed excellent dielectric properties, due to the prevention from reduction of titanium caused by the valence state change of Mn.In contrast with Mn doped samples, the density, average grain size and relative permittivity decreased with increasing Mo contents. An oxygen atmosphere had a detrimental effect on both microstructure and dielectric properties. The relative permittivity and Q×f value of air-sintered samples were both higher than those sintered in oxygen, possibly due to the formation of oxide film during the sintering process to degrade the sintering behaviour.Mn addition improved the microwave dielectric properties of 0.24ZN-0.76ZT ceramic effectively: the results ofε_r～46, Q×f～40800 GHz andτ_f～0.2 ppm/℃were obtained with 0.1 wt% Mn doping for samples sintered in oxygen.