"Structure, defects, and microwave dielectric properties of Al-doped an" by Weijia GUO, Zhiyu MA et al.

Article Title

Structure, defects, and microwave dielectric properties of Al-doped and Al/Nd co-doped Ba₄Nd_9.33Ti₁₈O₅₄ ceramics

Authors

Weijia GUO, State Key Laboratory of New Ceramics and Fine Processing, School of Materials Science and Engineering, Tsinghua University, Beijing 100084, China
Zhiyu MA, State Key Laboratory of New Ceramics and Fine Processing, School of Materials Science and Engineering, Tsinghua University, Beijing 100084, China
Yu LUO, State Key Laboratory of New Ceramics and Fine Processing, School of Materials Science and Engineering, Tsinghua University, Beijing 100084, China
Yugu CHEN, State Key Laboratory of New Ceramics and Fine Processing, School of Materials Science and Engineering, Tsinghua University, Beijing 100084, China
Zhenxing YUE, State Key Laboratory of New Ceramics and Fine Processing, School of Materials Science and Engineering, Tsinghua University, Beijing 100084, China
Longtu LI, State Key Laboratory of New Ceramics and Fine Processing, School of Materials Science and Engineering, Tsinghua University, Beijing 100084, China

Keywords

microwave dielectric ceramics, Ba4Nd9.33Ti18O54 (BNT), Al and Al/Nd doping, structural and defect modulation

Abstract

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 Ba₄Nd_9.33Ti₁₈O₅₄ (BNT) ceramics with a chemical formula of Ba₄Nd_9.33+z/3Ti_18-zAl_zO₅₄ (BNT-AN, 0 ≤ z ≤ 2) was proposed to improve the dielectric properties through structural and defect modulation. Together with Al-doped ceramics (Ba₄Nd_9.33Ti_18-zAl_4z/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 amount z increased, the relative dielectric constant (ε_r) and the temperature coefficient of resonant frequency (τ_f) of the ceramics decreased, and the Q×f values of the ceramics obviously increased when z ≤ 1.5. Excellent microwave dielectric properties of ε_r = 72.2, Q×f = 16,480 GHz, and τ_f = +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.

Recommended Citation

GUO, Weijia; MA, Zhiyu; LUO, Yu; CHEN, Yugu; YUE, Zhenxing; and LI, Longtu (2022) "Structure, defects, and microwave dielectric properties of Al-doped and Al/Nd co-doped Ba₄Nd_9.33Ti₁₈O₅₄ ceramics," Journal of Advanced Ceramics: Vol. 11: Iss. 4, Article 11.
DOI: https://doi.org/10.1007/s40145-021-0564-0
Available at: https://dc.tsinghuajournals.com/journal-of-advanced-ceramics/vol11/iss4/11

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