Game-changing high-performance semiconductor material could help reduce heat emissions — ScienceDaily

Researchers at West Virginia University have developed a material with the potential to dramatically reduce the amount of heat energy released into the atmosphere.

A team led by Xueyan Song, professor and George B. Berry Chair of Engineering in the Benjamin M. Statler College of Engineering and Mineral Resources, has created an oxide ceramic material that solves a long-standing performance problem plaguing thermoelectric generators. These devices can generate electricity from heat, including the heat emissions of power plants, which contribute to global warming.

The pioneering ceramic oxide produced by Song’s team “achieved a record performance that had been thought impossible,” he said. “We demonstrated the best thermoelectric oxide ceramics reported in the field worldwide in the last 20 years, and the results open up new research directions that could further increase performance.”

Cesar Octavio Romo de la Cruz, Yun Chen, Liang Liang, and Sergio A. Paredes Navia contributed to the study, supported by $639,784 in National Science Foundation funding. The findings appear in Renewable Energy and Sustainable Energy Reviews.

Oxide ceramics are from the same family as materials such as ceramics, porcelain, clay bricks, cement and silica, but contain various mineral elements. They are tough, resistant to heat and corrosion and are suitable for applications at high temperatures in air. They can serve as material for thermoelectric generator components.

However, oxide ceramics have “polycrystalline” structures consisting of multiple bonded crystals. Engineers face problems with large-scale thermoelectric applications for these materials because the “grain boundaries,” the places where these crystals meet, block the current and flow of electrons that power thermoelectric generators.

Song’s team turned that hurdle into a stepping stone.

“We deliberately added ‘dopants’ or metal ions to the polycrystalline ceramics, driving specific types of impurities to segregate at the grain boundaries,” said postdoctoral researcher Romo de la Cruz. “Thus we turned the inevitable and damaging grain boundaries into pathways for the conduction of electricity, greatly improving the thermoelectric efficiency.”

The research responds to the growing problem of waste heat, which contributes to climate change and is a byproduct of most operations that convert fuel into energy. When bulbs get hot to the touch, they emit waste heat: inefficient extra energy that doesn’t contribute to their primary job of producing light. Waste heat is released into the atmosphere by systems as diverse as power plants, home heating systems and cars, and enough is emitted that the global market for systems that recover it will top $70 billion by 2026.

“Heat is used to produce almost everything, from food to metals and electricity,” explained Romo de la Cruz. “But during these processes, around 60% of the energy produced is unproductively released into the environment as heat. Waste heat recovery will play an increasingly key role in balancing the growing demand for electricity against the carbon footprint of industrial processes. Thermoelectric oxide ceramics like ours come into play by essentially improving the ability of thermoelectric generators to convert waste heat into electricity.”

Thermoelectric generators are a promising technology for waste heat recovery in part because they are simple to operate and maintain. A powerful thermoelectric generator could capture a significant portion of a power plant’s waste heat.

But “for the majority of applications, thermoelectric technology is too inefficient to be economical,” Song said. “Thermoelectric’s lack of efficiency in converting energy severely hinders the development of thermoelectric devices, even though they are desperately needed.”

Her lab solved this problem by using nanostructure engineering — manipulating the crystalline structure of the ceramic at an atomic scale that can only be seen using an electron microscope — to create a dense polycrystalline material with a texture that surpassed the single-crystalline materials on the surface. present standard.

Although tuning the performance of various materials for thermoelectrics has stimulated intense theoretical and experimental work for decades, Song believes that for bulk oxide ceramics, her lab is the first to demonstrate a significant increase in the efficiency of power generation from heat through of the nano- and atomic-scale mechanics of grain boundaries between crystals.

“This project is on the threshold of large-scale, high-temperature waste heat recovery,” he said. “It ushers in a new era for oxide ceramics and aligns with the US Department of Energy’s Industrial Heat Shot initiative to develop competitive industrial heat shot technologies with at least 85% lower greenhouse gas emissions by 2035. Our findings could facilitate and accelerate materials design that is far beyond the current state of the art.”

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