The Preparation And Properties Of ZnO-Ni₂₃-TiO₂-Nb₂O₅and BaO-TiO₂-Nb₂O₅Microwave Dielectric Ceramics

The ZnO-Ni2O3-TiO2-Nb2O5and BaO-TiO2-Nb2O5ceramics were synthesizedby the conventional solid-state reaction method. The crystal structure and microwavedielectric properties were investigated by XRD, SEM, XPS and dielectricmeasurements. The micro-structure and microwave dielectric properties wereinvestigated by doping modification and process optimization.To optimize temperature coefficient of resonant frequency, the Ni element wasselected as the substitution for Zn site, and the microwave dielectric properties ofZn1-xNixTiNb2O8samples (x=0,0.1,0.2,0.3,0.4) were investigated. The XRDpatterns of Zn1-xNixTiNb2O8ceramics showed that ZnTiNb2O8phase andNi0.5Ti0.5NbO4phase were obtained, resulting in the increase of dielectric constant andthe decrease of Q×f value. Moreover, the temperature coefficient of resonantfrequency (τf) shifted to a positive value with increasing Ni content. The near-zerotemperature coefficient of resonant frequency were obtained for Zn0.7Ni0.3TiNb2O8ceramics:r=41.36, Q f=31760GHz, τf=-9.2ppm/°C.To improve the dieletric constant, the Zn element was chosen as the substitute forNi site and the microwave dielectric properties of Ni0.5-xZnxTi0.5NbO4(x=0.10,0.15,0.20,0.25) ceramics were investigated. When x was equal to0.10, a single phase wasobtained (Ni0.5Ti0.5NbO4). Considering the similar parameter between the Zn and theNi element, the single phase should be (Ni, Zn)0.5Ti0.5NbO4solid solution. But thenwith the increase of Zn content, the second phase (ZnTiNb2O8) appeared. Thedielectric constant was enhanced for Ni0.5Ti0.5NbO4ceramics by proper Zn doping forNi site, which was relevant to the existence of (Ni, Zn)0.5Ti0.5NbO4solid solution. Theexcellent microwave dielectric properties were obtained for Ni0.5-xZnxTi0.5NbO4ceramics (x=0.20):r=62.54, Q f=13,500GHz, τf=+65ppm/°C.In this paper, the microwave dieletric properties of Ba6TiNb4O18ceramics werestudied. The article explores the effect of synthesised method, synthesised temperature,milling time, holding time and B-site doping on Ba6TiNb4O18system microwavedielectric ceramics. The excellent microwave dielectric properties were obtained forBa6TiNb3.96Mn0.04O17.94ceramics:r=42.36，Q×f=15138GHz.