Simultaneous Realization of High Dielectric Constant and Ultrahigh Quality Factor in SrTiO 3 via a Tunable Grain Growth Strategy

作者：Yuhang Zhang, Guoxiang Zhou, Yanzhao Zhang, Meiling Yang, Kunpeng Lin, Zhe Zhao, Yunpeng He, Ning Xie, Zhihua Yang, Dechang Jia, Yu Zhou · 发表于：ACS Applied Materials & Interfaces · 年份：2025 · DOI：10.1021/acsami.5c11750 · 被引用次数：6 · 研究领域：Ferroelectric and Piezoelectric Materials、Microwave Dielectric Ceramics Synthesis、Electronic and Structural Properties of Oxides

In high-performance dielectric ceramics, grain boundaries are the primary reason attributed to microwave dielectric losses; therefore, increasing grain size to reduce their density effectively enhances dielectric properties. Although ion doping shows promising modification effects, how to control the grain size by ion codoping has been barely investigated due to the unclear nucleation and growth mechanism. Previous ion doping did not precisely control the grain size of the dielectric ceramic owing to its high nucleation density and low grain boundary mobility, typically resulting in sub-20 μm grains. In this study, combining the effect of Al/Ta codoped SrTiO 3 (ST- x AT, x = 0–0.1) microwave dielectric ceramics, anomalous crystal nucleation and growth were observed. To confirm the grain size effect on optimizing the dielectric properties, the prolonged sintering process was implemented to further increase the grain size of the Al/Ta codoped ceramics, which other doping strategies fail to replicate. Consequently, the average grain size of the obtained Al/Ta codoped SrTiO 3 is 4 times greater than existing cases. When ST-0.02AT was sintered at 1550 °C for 8 h, the outstanding dielectric properties of Q × f ∼ 10,681 GHz (at 3.3 GHz) were achieved, representing a 268% improvement compared to the undoped sample ( Q × f ∼ 2901 GHz) while maintaining a high dielectric constant ε r ∼ 258.01. Meanwhile, the intrinsic factors and growth mechanism of dielectric properties were explained...