Advanced Microwave Processing for Next-Generation Materials.

The next generation of technological innovations demands viable synthesis, processing, and manufacturing techniques. Conventional approaches, relying on traditional heating methods, are often energy-intensive, time-consuming, and costly. Furthermore, they face persistent challenges such as nonuniform heating, processing inefficiency, and limitations in achieving desired structures and properties. The interaction of electromagnetic (EM) fields, such as microwaves, with materials, offers an alternative technique to address these limitations, enabling numerous discoveries in the field of materials science. The term "microwave" refers to alternating EM signals within the frequency range of 300 MHz to 300 GHz, with corresponding wavelengths of 1 m to 1 mm. Unlike conventional heating, which relies on slow surface-to-core heat transfer via convection, radiation, and conduction, microwave energy interacts with materials at the atomic level, heating the entire volume simultaneously through volumetric EM energy absorption. This process is typically rapid and energy-efficient and is dictated by the material's inherent transport properties. In addition, the unique, nonthermal effects of microwaves, including field-induced alloy decomposition, decrystallization, enhanced solid-state reactions, and defect generation, are particularly compelling. These phenomena are thermodynamically nonequilibrium and are essential for developing materials and structures with extraordinary properties. The combination of external microwave electric and magnetic fields can, in fact, result in unique material structures, such as amorphous, amorphous-crystalline, textured, and defective states. This paper reviews the basic concepts of microwave interaction with solid-state materials and recent advancements in emerging materials science fields, including advanced ceramics, batteries, renewable energies, carbonaceous materials, high-entropy alloys, and advanced processes like joining, 3D printing, and recycling. Ultimately, this work introduces advanced microwave processing as a powerful, cleaner, faster, and more effective strategy for the discovery, synthesis, and processing of next-generation materials.