The thermally-stimulated relaxation of defects in La,Al co-substituted (Ba,Sr)La₄Ti₄O₁₅ dielectric ceramics with hexagonal perovskite structure were investigated systematically with the thermally stimulated depolarization current (TSDC) measurements. The ion substitution decreased the lattice parameters and the bond lengths of the cations and O²⁻. TSDC spectra indicated the main extrinsic defects in the ceramics were oxygen vacancies and the concentration of oxygen vacancies decreased with the increasing ion substitutions, which was derived from the decrease in the lattice parameters. The terahertz time-domain spectra indicated the damping factor of lattice vibration was reduced with the decline of the concentration of oxygen vacancies, which decreased the microwave/terahertz dielectric loss. High-performance (Ba_0.2Sr_0.8)_0.75La_4.25Ti_3.75Al_0.25O₁₅ (ε_r = 43.9, Q × f = 84300 GHz, τ_f = -18.0 ppm/°C) ceramics were obtained. The correlations between crystal structures, defect behaviors and dielectric properties discussed in this work could provide guidance for the modification of microwave dielectric ceramics.

通过热激去极化电流 (TSDC) 测量系统地研究了具有六方钙钛矿结构的La,Al 共取代 (Ba,Sr)La ₄ Ti ₄ O ₁₅介电陶瓷中缺陷的热激弛豫。离子取代降低了晶格参数以及阳离子和 O ^2-的键长. TSDC 谱表明陶瓷中的主要外在缺陷是氧空位，氧空位的浓度随着离子取代度的增加而降低，这是由于晶格参数的降低。太赫兹时域光谱表明，随着氧空位浓度的降低，晶格振动的阻尼因子减小，从而降低了微波/太赫兹介电损耗。高性能 (Ba _0.2 Sr _0.8 ) _0.75 La _4.25 Ti _3.75 Al _0.25 O ₁₅ ( ε _r = 43.9, Q × f = 84300 GHz, τ _f= -18.0 ppm/°C) 陶瓷。本工作中讨论的晶体结构、缺陷行为和介电性能之间的相关性可以为微波介电陶瓷的改性提供指导。