摘要
Low-loss tungsten–bronze microwave dielectric ceramics are dielectric materials with potential application value for miniaturized dielectric filters and antennas in the fifth-generation(5G)communication technology.In this work,a novel Al/Nd co-doping method of Ba_(4)Nd_(9.33)Ti_(18)O_(54)(BNT)ceramics with a chemical formula of Ba_(4)Nd_(9.33+z/3)Ti_(18−z)Al_(z)O_(54)(BNT–AN,0≤z≤2)was proposed to improve the dielectric properties through structural and defect modulation.Together with Al-doped ceramics(Ba_(4)Nd_(9.33)Ti_(18−z)Al_(4z/3)O_(54),BNT–A,0≤z≤2)for comparison,the ceramics were prepared by a solid state method.It is found that Al/Nd co-doping method has a significant effect on improving the dielectric properties compared with Al doping.As the doping amount z increased,the relative dielectric constant(εr)and the temperature coefficient of resonant frequency(τf)of the ceramics decreased,and the Q×f values of the ceramics obviously increased when z≤1.5.Excellent microwave dielectric properties ofεr=72.2,Q×f=16,480 GHz,andτf=+14.3 ppm/℃were achieved in BNT–AN ceramics with z=1.25.Raman spectroscopy and thermally stimulated depolarization current(TSDC)technique were firstly combined to analyze the structures and defects in microwave dielectric ceramics.It is shown that the improvement on Q×f values was originated from the decrease in the strength of the A-site cation vibration and the concentration of oxygen vacancies(VO××),demonstrating the effect and mechanism underlying for structural and defect modulation on the performance improvement of microwave dielectric ceramics.
基金
This work was supported by the National Key R&D Program of China(No.2017YFB0406301)
the Key-Area Research and Development Program of Guangdong Province(No.2020B010176001)
the National Natural Science Foundation of China(No.51872160).
