ZrO₂-(Zn_1/3A_2/3)O₂-TiO₂?A=Nb,Sb? Microwave Dielectric Ceramics With Moderate Permittivity And Low Loss

Rapid development of mobile communication industry calls for increasingly high quality of microwave dielectric ceramics.The microwave dielectric ceramics of low loss moderate permittivity is important part of filters,resonators,dielectric antenna and other microwave devices,which indicates the study of microwave dielectric ceramics is significant.As the microwave dielectric ceramics of ZrO₂-TiO₂ system obtains moderate permittivity and high quality factors,it has been extensively researched.However,the extremely high positive temperature coefficient of resonance frequency and a sintering temperature of higher than1600?hinder the practicality of ZrO₂-TiO₂ system,which is more of a theory.Based on the problems above,(Zn_1/3A_2/3)O₂?A=Nb,Sb?is used to optimize the microwave dielectric properties of ZrO₂-TiO₂ system.The relationships among phase composition,microstructure,Raman spectrum,infrared spectrum and microwave dielectric properties.This article first investigates the influences of(Zn_1/3Nb_2/3)O₂ doping on the sintering behavior and microwave dielectric properties of ZrTiO₄ system,and the formula is?1-x?/2ZrO₂-x(Zn_1/3Nb_2/3)O₂-?1-x?/2TiO₂?0.05?x?0.40?.In the case of 0.5wt%CuO dropping,the added(Zn_1/3Nb_2/3)O₂ can be essentially dissolved into ZrTiO₄ lattice.As x increasing from 0.05 to 0.45,the sintering temperature can be decreased greatly,so are the relative permittivity and temperature coefficient of resonance frequency.However,the quality factor exhibits a significant improvement.From the Raman spectra we can find that the distortion of TiO₆ octahedron was enhanced,thus lead to the decrease of?_f value.Through the infrared reflection spectra the intrinsic?_r and Q×f was calculated,and theoretical?_r was in line with experimental value while theoretical Q×f was higher than mearsurement value.The best properties of?1-x?/2ZrO₂-x(Zn_1/3Nb_2/3)O₂-?1-x?/2TiO₂ ceramics appeared at x=0.25:?_r=35.1,Q×f=40341GHz,?_f=-0.6ppm/?.As different ZrO₂-TiO₂ ratio would make great influence on microwave dielectric properties,the forth chapter investigates the effects of(Zn_1/3Nb_2/3)O₂ substitution on ZrTi₂O₆,and the formula is?1-x?/3ZrO₂-x(Zn_1/3Nb_2/3)O₂-2?1-x?/3TiO₂?0.05?x?0.45??With 0.5wt%CuO dropping,TiO₂ second phase occurred at low(Zn_1/3Nb_2/3)O₂ addition area,thus make some influences on microwave dielectric properties.The best properties of?1-x?/3ZrO₂-x(Zn_1/3Nb_2/3)O₂-2?1-x?/3TiO₂?0.05?x?0.45?lies at x=0.25:?_r=42.8,Q×f=41300GHz,?_f=4.5ppm/?.In order to make further performance improvement on the microwave dielectric properties,(Zn_1/3Sb_2/3)O₂ is used in ZrTiO₄ system for the first time,and the formula is?1-x?/2ZrO₂-x(Zn_1/3Sb_2/3)O₂-?1-x?/2TiO₂?0.05?x?0.30?.It can be revealed that the solid solubility of(Zn_1/3Sb_2/3)O₂ in ZrTiO₄ is 0.25,and a small amount of(Zn_1/3Sb_2/3)O₂ can promote Q×f value dramatically.The best property appeared at x=0.15:?_r=38.0,Q×f=42306GHz,?_f=1.27ppm/?.