December 9, 2024 by Center for Research in Biological Chemistry and Molecular Materials (CiQUS)
Collected at: https://phys.org/news/2024-12-modulation-electric-fields-enables-creation.html
Overheating in electronic devices affects how it works and how long it lasts. One of the major challenges is efficiently managing the heat generated by these systems during operation, which involves controlling the thermal conductivity of the materials they comprise. While electric current can be easily manipulated in conventional electronic materials, heat presents a different challenge: phonons, the particles that transport heat in crystalline solids, lack both charge and magnetic moment, making them much harder to control.
A new technique developed by researchers at the Center for Research in Biological Chemistry and Molecular Materials (CiQUS) enables the creation of thermal circuits in certain iron and cobalt oxides, effectively regulating heat flow in highly localized areas of these materials. The paper is published in the journal Advanced Materials.
“Using this technique, we’ve managed to reduce thermal conductivity by up to 50% in micrometric regions of various materials,” explains Francisco Rivadulla, the study’s lead researcher and Professor of Physical Chemistry at the University of Santiago de Compostela (USC).
Much like a precise engraving, the scientists used the tip of an atomic force microscope to apply a highly localized electric field to the material’s surface, forming micrometric patterns with defined thermal conductivity.
“By applying the electric field, we were able to control the local concentration of oxygen ions within the material. These ions act as barriers to phonon propagation, determining the material’s thermal conductivity,” details Dr. Marcel Claro, another author of the study. This research, led by Rivadulla’s team at CiQUS, also involved contributions from Professors Carlos Vázquez and Arturo López Quintela from iMATUS.Play
A stable and reversible process
Using this technology, the researchers successfully applied electric fields of millions of volts per centimeter, enabling the movement and accumulation of negative oxygen ions within the material to create artificial barriers for heat propagation.
“By optimizing the oxide’s composition, we ensured that the process—the alternation between different thermal states—is stable over time,” explains Noa Varela, the study’s lead author.
“The areas with reduced thermal conductivity remain stable under ambient conditions but can be reversed with slight heating in air. This allows the material to be reused, repeating the thermal conductivity modification process as many times as needed,” preserving the functionality of the devices through multiple cycles.
Thermal electronics
The work represents a significant step forward in heat management for microelectronics, paving the way for components that can control heat dissipation in various devices and energy storage systems.
The main goal of this research group is to develop systems capable of controlling heat flow in nano- and microstructures as efficiently as electrical circuits handle current. In this context, thermal transistors—capable of regulating heat transport in response to electrical stimuli—are poised to play a pivotal role in the next generation of devices.
More information: Noa Varela‐Domínguez et al, Electric‐Field Control of the Local Thermal Conductivity in Charge Transfer Oxides, Advanced Materials (2024). DOI: 10.1002/adma.202413045
Journal information: Advanced Materials
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