JNCASR Researchers Discover Unusual Heat Transport Mechanism in Copper Chalcogenide Material
Researchers at Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR), Bengaluru, an autonomous institution under the Department of Science & Technology, Government of India, have made a significant breakthrough in thermoelectric materials science. The team discovered an unusual wave-like heat transport regime in a newly studied copper chalcogenide material called thallium copper selenide (TlCu5Se3) that could revolutionize waste heat conversion efficiency across multiple industries.
The complex crystal framework of TlCu5Se3 features a tetragonal structure that forms a complex three-dimensional cloverleaf knot-like framework with open channels along the crystallographic c-axis. This structure restricts the motion of copper atoms through confined ion diffusion rather than allowing long-range migration, which generates exceptionally strong anharmonicity while preserving structural stability. The research team, led by Prof. Kanishka Biswas with Ph.D. students Ms. Sayantoni Choudhury and Dr. Animesh Bhui from the New Chemistry Unit at JNCASR, collaborated with Prof. Umesh V. Waghmare and Dr. Prasad V. Matukumilli from the Theoretical Sciences Unit for advanced first-principles theoretical calculations and molecular-dynamics simulations.
Molecular-dynamics simulations revealed that copper atoms exhibit localized dynamic disorder rather than the long-range, liquid-like diffusion characteristic of superionic copper chalcogenides. This confined motion acts primarily as a source of strong lattice anharmonicity, causing heat to propagate through wave-like coherence with phonons tunneling between localized vibrational states rather than moving as well-defined particles. The team employed the unified formalism of thermal transport framework that considers both particle-like phonon propagation and wave-like coherence between different phonon branches.
The material achieved an exceptionally high thermoelectric performance with a thermoelectric figure of merit (zT) of 1.7, ranking among the highest for pristine ternary chalcogenides. This breakthrough enables efficient conversion of waste heat to electricity via thermoelectric energy conversion in power plants, cement industries, steel plants, automobiles, data centers, and battery heat management systems. The research also has applications in thermal barrier coatings and thermal decoherence-free quantum technology.
The study, published in the prestigious journal Science Advances (DOI:10.1126/sciadv.aeh9096), establishes how structural complexity and confined ion dynamics can lead to an unconventional mechanism for thermal management and high-performance thermoelectric energy conversion. The discovery represents a significant advancement in materials science with potential broad industrial applications for energy efficiency and waste heat recovery.