Authors: Weijia Guo, Zhiyu Ma, Yu Luo, Yugu Chen, Zhenxing Yue, Longtu Li
Published: 2022-02-27
DOI: 10.1007/s40145-021-0564-0
Source: Full article
AbstractLow-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 Ba4Nd9.33Ti18O54(BNT) ceramics with a chemical formula of Ba4Nd9.33+z/3Ti18−zAlzO54(BNT-AN, 0 ⩽z⩽ 2) was proposed to improve the dielectric properties through structural and defect modulation. Together with Al-doped ceramics (Ba4Nd9.33Ti18−zAl4z/3O54, 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 amountzincreased, the relative dielectric constant (εr) and the temperature coefficient of resonant frequency (τf) of the ceramics decreased, and theQ×fvalues of the ceramics obviously increased whenz⩽ 1.5. Excellent microwave dielectric properties ofεr= 72.2,Q×f= 16,480 GHz, andτf= +14.3 ppm/°C were achieved in BNT-AN ceramics withz= 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 onQ×fvalues was originated from the decrease in the strength of the A-site cation vibration and the concentration of oxygen vacancies ($${\rm{V}}_{\rm{O}}^{ \cdot \cdot }$$VO⋅⋅), demonstrating the effect and mechanism underlying for structural and defect modulation on the performance improvement of microwave dielectric ceramics.