Effect of Nd3+ and Sm3+ doping on the crystal structure and dielectric properties of Y2-xAxMgTiO6 ceramics

In the era of rapid technological development, microwave communication technology is advancing rapidly towards higher frequencies, higher speeds, and smaller sizes. With the gradual deployment of 5G/6G communication networks and the continuous expansion of applications in the millimeter-wave and even terahertz frequency bands, extremely stringent requirements are placed on the performance of microwave devices. Microwave dielectric ceramics, as the core materials in microwave devices, directly determine the signal transmission quality and efficiency.In previous studies, Y₂MgTiO₆ (YMT) ceramics have shown certain characteristics in the microwave field, laying a foundation for further research. However, with the increasing demand for low-loss and high-stability microwave dielectric materials in communication technology, it is urgent to further optimize the performance of YMT ceramics.

Against this backdrop, a research team led by Hongcheng Yang from Southwest Petroleum University conducted an in-depth investigation into the effects of ion doping on Y₂MgTiO₆ microwave dielectric ceramics, precisely introducing neodymium (Nd) and samarium (Sm) ions into Y₂MgTiO₆ within its solid-solution range using the solid-state sintering method, accurately analyzing the alterations in phase composition and crystal structure with the Rietveld refinement method, exploring the lattice vibration characteristics with Raman and far-infrared reflection spectroscopy, and systematically elucidating the mechanisms by which Nd and Sm doping affected the material's dielectric properties at various levels to lay a solid theoretical foundation for the rational design and optimization of microwave dielectric materials.

The team published their work in Journal of Advanced Ceramics on April 24, 2025.

Y₂MgTiO₆ ceramics, studied previously by Hongcheng Yang's team, showed some microwave dielectric properties, yet room for enhancement remained. So, they applied ion doping, a common way to optimize ceramic performance.

"With Nd³⁺ and Sm³⁺ doping, YMT ceramics reached a relative density over 95% (up to 98.2%) at the optimal sintering temperature. XRD and Rietveld refinement revealed pure phase Y₂MgTiO₆ solid solutions in all doped samples, with Nd³⁺ and Sm³⁺ replacing Y³⁺ and keeping lattice integrity, which is fundamental for performance tuning," Hongcheng Yang said.

"The rise in the Q×f value, representing improved dielectric properties, results from the combined effect of chemical bond features and lattice energy. For Nd doping (x = 0.1), the Q×f peak hit 74,821 GHz, a 20% boost from undoped samples. For Sm doping (x = 0.05), it reached 67,068 GHz, a 15% increase. Doping ions optimize properties by balancing chemical bond ionicity, bond energy, and lattice stability," Yang added.

"Dielectric loss mainly comes from low - frequency lattice vibrations (<400 cm⁻¹). Nd doping reduces lattice symmetry, creating new peaks in 600-750 cm⁻¹ (lifting phonon degeneracy), with the first five modes contributing 93.87% of the loss. Sm doping makes low frequency Mg-O/Ti-O vibrations dominant, contributing 80.93%. Far infrared and terahertz spectra confirm the key role of low - frequency vibrations. Rare earth doping strengthens lattice rigidity, reduces phonon scattering, and cuts loss," Yang further explained.

"These tunable dielectric properties make YMT-based ceramics great for next generation communication systems, especially 5G/6G low loss components. But more research is needed. Future work can focus on optimizing doping, studying material stability over time and with temperature, and improving performance in complex environments," Yang concluded.

Other contributors include Xier Huang and Jin Zhang from the School of New Energy and Materials, Southwest Petroleum University, Chengdu, China; Enzhu Li from the National Engineering Research Center of Electromagnetic Radiation Control Materials and the Key Laboratory of Multi-Spectral Absorbing Materials and Structures of the Ministry of Education, University of Electronic Science and Technology of China; Enxiang Guan and Ruzhong Zuo from the Anhui Key Laboratory of Low Temperature Co-fired Materials, School of Chemistry and Materials Engineering, Huainan Normal University, Huainan, China.

This work is supported by the National key research and development program (2022YFB2807405); National Natural Science Foundation of China (U2341263); Sichuan Science Technology Program (MZGC20240121); Natural Science Starting Project of SWPU (2022QHZ022).

About Author

Hongcheng Yang is an associate professor in the School of New Energy and Materials at the Southwest Petroleum University, working on fundamental and application research of dielectric ceramics and devices. She received her Ph.D. in 2022 in the University of Electronic Science and Technology of China. Her research interests focus on functional ceramics and devices, including the microwave dielectric ceramics, glass-ceramics and their practical application in microwave devices and package substrates.

About Journal of Advanced Ceramics

Journal of Advanced Ceramics (JAC) is an international academic journal that presents the state-of-the-art results of theoretical and experimental studies on the processing, structure, and properties of advanced ceramics and ceramic-based composites. JAC is Fully Open Access, monthly published by Tsinghua University Press, and exclusively available via SciOpen. JAC’s 2023 IF is 18.6, ranking in Top 1 (1/31, Q1) among all journals in “Materials Science, Ceramics” category, and its 2023 CiteScore is 21.0 (top 5%) in Scopus database. ResearchGate homepage: https://www.researchgate.net/journal/Journal-of-Advanced-Ceramics-2227-8508