This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: Advanced materials power everything from batteries and electronics to clean energy technologies. For years, engineers have known that microwave-assisted synthesis can dramatically accelerate the chemical reactions used to manufacture these materials.
Now, researchers at Carnegie Mellon University have provided new evidence challenging a long-held assumption about why, suggesting that microwaves speed chemical reactions in a fundamentally different way than many scientists believed. The study, led by Reeja Jayan, a professor of mechanical engineering, and CMU alumnus Morgan Chen, challenges the long-held belief that microwaves accelerate chemical reactions by lowering the amount of energy needed for those reactions to occur. Instead, the team found evidence that microwaves increase how often molecules successfully rearrange themselves into new materials.
To reach that conclusion, Jayan and Chen studied the formation of tin oxide nanoparticles, a material used in batteries, catalysts and other electronic devices. Using high-energy X-rays, they watched the nanoparticles form in real time under both conventional and microwave-assisted heating, allowing them to compare how the atomic structure evolved throughout each reaction. By pairing these real-time observations with mathematical modeling, the researchers found that microwave-assisted synthesis did not appear to lower the reaction's activation energy as expected.
Instead, microwave irradiation significantly increased the likelihood of successful molecular interactions, enabling the material to crystallize more quickly. The work is published in the Journal of Materials Chemistry A. "Since 2015, my group has been studying the effects of microwaves on manufacturing," said Jayan.
"This new paper unlocks a vital 'missing link' mechanism that is broadly applicable to everyone who uses microwaves, from home cooks to aerospace and heavy industry." These findings also provide researchers with a clearer framework for designing faster and more energy-efficient manufacturing processes. Understanding how microwaves influence chemical reactions could improve the production of advanced materials. Additionally, the work demonstrated a powerful new approach for studying materials as they form.
Rather than examining only the finished product, the team combined in situ synchrotron X-ray scattering with atomic-scale structure analysis to observe chemical reactions as they unfolded. "This same approach can be applied to other material systems, giving scientists a new way to understand how materials form and ultimately optimize the manufacturing processes used to create them," explained Chen. Morgan Chen et al, Comparison of the Arrhenius parameters between conventional hydrothermal and microwave-assisted synthesis methods for tin oxide nanoparticles, Journal of Materials Chemistry A (2026).
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