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Refrigeration and cooling account for more than 17 percent of electricity consumption worldwide. However, the fundamentals of the vapor compression cycle that are used for most refrigeration applications have changed little since they were developed in the mid-19th century. As the global dependence on commercial and residential refrigeration and cooling increases, the need for next generation refrigerant materials becomes significant.

Patrick ShambergerDr. Patrick Shamberger, assistant professor in the Department of Materials Science and Engineering at Texas A&M University, is conducting fundamental research on magnetic cooling technology that can heat up when magnetized and cool down when the magnetic field is removed.

High-efficiency magnetic refrigerants could potentially consume much less electricity than traditional vapor-compression refrigerators and heat pumps. However, every time the magnetic field is changed, abrupt energy loss or hysteresis occurs.

In July, Shamberger received a grant from the National Science Foundation (NSF) to study the microscopic mechanism causing the energy loss to understand how to design high-efficiency near-room temperature magnetic refrigerants. The proposal, “Understanding Mechanisms in Magneto-Structural Transformations,” received $382,000 from NSF.

Shamberger’s research seeks to investigate the phase transformation mechanisms in the iron phosphide class of alloys (Fe2P). It is known that the Fe2P alloys exhibit magnetocaloric effect which is the thermal response of a magnetic material to the change of an external magnetic field which results in temperature change.

The research aims to explore the mechanisms responsible for low-hysteresis transformation in Fe2P alloys and, additionally, may provide insights into hysteresis engineering in other functional materials such as shape memory alloys.

“There is very little theory to describe why we can achieve very small hysteresis in this one class of Fe2P, but we have not been able to achieve anything close on other common classes of magnetocaloric effect materials,” said Shamberger. “Really, the goal here is to take lessons from one particular class of materials, and apply this to the greater understanding of the origins of hysteresis in solid-solid magnetostructural phase transformations.”