Microwave This comprehensive review provides an in-depth exploration of the pivotal role played by microwave dielectric ceramics in the ever-evolving landscape of 5G communication technology. With the advent of 5G, characterized by ultra-high frequency, extensive bandwidth, and low latency, microwave dielectric ceramics have become indispensable components, providing essential support for high-speed data transmission. Their applications extend across critical components such as antennas, filters, and Radio Frequency (RF) front-end modules within microwave communication systems.

As 5G technology advances and communication frequencies escalate, new challenges and heightened technical requirements have surfaced, necessitating continuous research and innovation in the field. This paper delves into key aspects of ongoing research, placing particular emphasis on the imperative to enhance the frequency response range, minimize material loss, and improve quality factors. These advancements are crucial to meeting the demands of high-speed data transmission inherent in 5G communication technology.

The paper categorizes microwave dielectric ceramics into low, medium, and high dielectric constant types, underscoring their irreplaceable roles in 5G communication devices. Applications in 5G antennas, filters, and RF front-end modules are detailed, providing a comprehensive understanding of the diverse and crucial functions these materials perform to enable advanced communication capabilities.

A thorough analysis of key technical requirements follows, with a focus on optimizing high-frequency characteristics, achieving low loss, and attaining high-quality factors. The review then explores the latest advancements in microwave dielectric ceramic materials, presenting developments in low, medium, and high dielectric constant ceramics. Innovations in these areas not only enhance the performance of existing 5G communication systems but also pave the way for the potential development of future-generation communication technologies.

Looking towards the future, the paper outlines essential directions for the field, recognizing the need to develop novel microwave dielectric ceramic materials to meet the evolving requirements of 5G and beyond. Emphasis is placed on optimizing environmentally friendly low-temperature sintering processes, which are integral for sustainable and energy-efficient production. Additionally, the integration of microwave dielectric ceramics with 5G communication devices is highlighted as a crucial area for further exploration.

As 5G progresses and the prospect of 6G looms, the material's frequency stability, high-temperature stability, and environmental temperature reliability become increasingly critical. This necessitates ongoing research and development efforts to ensure the continued success and widespread application of 5G technology.

In conclusion, this extensive review provides valuable insights into the current state, challenges, and future prospects of microwave dielectric ceramics in 5G communication. Addressing these challenges and pursuing the outlined research directions will undoubtedly contribute significantly to the continued innovation and success of 5G technology, ensuring its widespread application and furthering the evolution of communication systems.

Yttria-stabilized zirconia (YSZ) has been used as a thermal barrier coating (TBC) material in gas turbines for several decades. Although continuous efforts have been made to develop novel TBC materials that can work at a higher temperature, no single material other than YSZ has all the desired attributes for the TBCs. In this paper, we report the in-situ synthesis of quasi-binary GdNbO₄/Gd₃NbO₇ composites based on the simple Gd₂O₃–Nb₂O₅ binary phase diagram. The fracture toughness of these quasi-binary composites is remarkably enhanced compared with the value predicted by the rule of mixtures because the ferroelastic domain switching is more activated due to the residual stress in the quasi-binary composites, which triggers more crack defections due to the enlarged process zone. Additionally, the Gd₃NbO₇ phase provides a low thermal conductivity due to the substantial chemical inhomogeneity, which diffuses phonons. Gd₃NbO₇/GdNbO₄ exhibits a balanced thermal conductivity of 1.6 W/(m·K) at 1073 K and a toughness value of 2.76 MPa·m^0.5, and these values are among the best comprehensive properties that have been obtained for new TBC materials. The work demonstrates a feasible approach of designing a new TBC material with balanced properties and can be easily fabricated.