Researchers adjust the thermal conductivity of materials ‘on the fly’ for more energy-efficient devices

Researchers adjust the thermal conductivity of materials 'on the fly' for more energy-efficient devices

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University of Minnesota Twin Cities PhD in Mechanical Engineering. students Yingying Zhang and Chi Zhang conduct measurements using a home-built system involving ultrafast laser pulses to study strontium and lanthanum cobaltite devices. Credit: Dingbin Huang, University of Minnesota

A team led by scientists and engineers at the University of Minnesota Twin Cities has discovered a new method for regulating the thermal conductivity of materials to control heat flow “on the fly”. Their tuning range is the highest ever recorded among single-step processes in the field and will open the door to the development of more energy-efficient and durable electronic devices.

The researchers’ paper is published in Nature communications.

Just as electrical conductivity determines how well a material can carry electricity, thermal conductivity describes how well a material can carry heat. For example, many metals used to make pans have high thermal conductivity so they can transport heat efficiently to cook food.

Typically, the thermal conductivity of a material is a constant and unchanging value. However, the University of Minnesota team discovered a simple process for “tuning” this value in strontium lanthanum cobaltite, a material often used in fuel cells. Similar to the way a switch controls the flow of electricity to a light bulb, the researchers’ method provides a way to turn the flow of heat in devices on and off.

“Controlling how well a material can transfer heat is of great importance in daily life and in industry,” said Xiaojia Wang, co-corresponding author of the study and an associate professor in the Department of Mechanical Engineering at the University of Minnesota. “With this research, we have achieved a record fine-tuning of thermal conductivity, demonstrating the promise of effective thermal management and energy consumption in the electronic devices people use every day. A well-designed and functioning thermal management system would enable better user experience and make devices more durable.”

Wang’s team worked in tandem with Chris Leighton, a professor at the University of Minnesota’s Distinguished McKnight University, whose lab specializes in materials synthesis.

Leighton’s team fabricated the lanthanum, strontium and cobaltite devices using a process called electrolytic gating, in which ions (molecules with an electrical charge) are driven onto the surface of the material. This allowed Wang and his research team to manipulate the material by applying a low voltage to it.

“Electrolytic gating is a tremendously powerful technique for controlling the properties of materials and is well established for voltage control of electronic, magnetic and optical behavior,” said Leighton, corresponding author of the study and a faculty member of the University of the Minnesota Department of Chemical Engineering and Materials Science. “This new work applies this approach in the realm of thermal properties, where voltage control of physical behavior is less explored. Our results establish low-power, continuously adjustable thermal conductivity over an impressive range, opening up some interesting potential applications of the device. . ”

“Although it was difficult to measure the thermal conductivity of lanthanum, strontium and cobaltite films because they are so ultrathin, it was quite exciting when we finally got the experiments going,” said Yingying Zhang, first author of the paper and a mechanic of the University of Minnesota. PhD in engineering student. ‘This project not only provides a promising example of fine-tuning the thermal conductivity of materials, but also demonstrates the powerful approaches we use in our laboratory to push the experimental limit for challenging measurements.’

More information:
Yingying Zhang et al, Continuous wide-range tuning of thermal conductivity of La0.5Sr0.5CoO3- films by ion-gel gating at room temperature, Nature communications (2023). DOI: 10.1038/s41467-023-38312-z

About the magazine:
Nature communications

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