New research from North Carolina State University sheds light on how electric fields can be used to alter the thermal properties of ferroelectric materials, allowing engineers to manipulate the flow of heat through the materials. Ferroelectric materials are used in a wide variety of applications, from ultrasound devices to memory storage technologies.
“Our work here is a significant advance because we worked with large sample sizes and provide detailed information on the relationship between the type of electric field being applied to the ferroelectric material and the thermal response in the material,” says Jun Liu, an associate professor of mechanical and aerospace engineering at NC State and corresponding author of the study. “In practical terms, this allows users to tune the thermal behavior of the material by applying different electric fields – using alternating current (AC) or direct current (DC) – which paves the way for developing new techniques for managing the flow of heat through various devices.”
For this work, the researchers worked with a ferroelectric material called PMN-PT, which is used in technologies such as sensors, actuators and ultrasound devices. To reflect real-world conditions, the researchers worked with 2.5 mm-thick samples at room temperature.
For the study, researchers applied electric fields of varying strengths to the material using both AC and DC sources. Other variables in their testing were the frequency of the current and the length of time that the material was exposed to the electric field.
The researchers then used a suite of methods to measure how each sample’s thermal properties changed in response to the different electric field conditions.
The researchers found that all four variables – the strength of the field, whether it was AC or DC, time and frequency – played a role in how the electrical field altered the material’s thermal properties.
“Having a detailed understanding of how each of the four variables influences the material’s thermal properties gives us a significant amount of control in engineering the material’s thermal behavior,” says Ankit Negi, a Ph.D. student at NC State and first author of a journal article on the study.
“We’re hoping to establish a similarly detailed understanding of the relationship between electric fields and thermal characteristics for other ferroelectric materials,” Liu says. “And we are open to collaborations on how this work could inform the development of new applications.”
The paper, “Ferroelectric Domain Wall Engineering Enabled Thermal Modulation in PMN-PT Single Crystals,” is published open access in the journal Advanced Materials. Co-authors are Hwang Pill Kim, a postdoctoral researcher at NC State; Anastasia Timofeeva and Xuanyi Zhang, Ph.D. students at NC State; Yong Zhu, Andrew A. Adams Distinguished Professor of Mechanical and Aerospace Engineering at NC State; Kara Peters, Distinguished Professor of Mechanical and Aerospace Engineering at NC State; Xiaoning Jiang, Dean F. Duncan Distinguished Professor of Mechanical and Aerospace Engineering at NC State; Divine Kumah, associate professor of physics at NC State; and Zilong Hua of Idaho National Laboratory.
The research was done with support from the National Science Foundation, under grant number 2011978; from the Office of Naval Research, under grant number N00014-21-1-2058; and through the INL Laboratory Directed Research & Development Program under DOE Idaho Operations Office Contract DE-AC07-05ID14517.
Note to Editors: The study abstract follows.
“Ferroelectric Domain Wall Engineering Enabled Thermal Modulation in PMN-PT Single Crystals”
Authors: Ankit Negi, Hwang Pill Kim, Anastasia Timofeeva, Xuanyi Zhang, Yong Zhu, Kara Peters, Divine Kumah, Xiaoning Jiang and Jun Liu, North Carolina State University; Zilong Hua, Idaho National Laboratory
Published: Feb. 16, Advanced Materials
Abstract: Acting like thermal resistances, ferroelectric domain walls can be manipulated to realize dynamic modulation of thermal conductivity (k), which is essential for developing novel phononic circuits. Despite the interest, little attention has been paid to achieve room-temperature thermal modulation in bulk materials due to challenges in obtaining a high thermal conductivity switch ratio (khigh/klow), particularly in commercially viable materials. Here, we demonstrate room-temperature thermal modulation in 2.5 mm-thick Pb(Mg1/3Nb2/3)O3–xPbTiO3 (PMN-xPT) single crystals. With the use of advanced poling conditions, assisted by the systematic study on composition and orientation dependence of PMN-xPT, we observed a range of thermal conductivity switch ratios with a maximum ≈1.27. Simultaneous measurements of piezoelectric coefficient (d33) to characterize the poling state, domain wall density using polarized light microscopy (PLM) and birefringence change using quantitative PLM reveal that compared to the unpoled state, the domain wall density at intermediate poling states (0< d33< d33,max) is lower due to the enlargement in domain size. At optimized poling conditions (d33,max), the domain sizes show increased inhomogeneity that leads to enhancement in the domain wall density. This work highlights the potential of commercially available PMN-xPT single crystals among other relaxor-ferroelectrics for achieving temperature control in solid-state devices.
This post was originally published in NC State News.