- Why in news
- On 14 September 2026, the Ministry of Science & Technology reported that JNCASR researchers found wave-like heat transport in the crystal TlCu5Se3. The finding could help turn industrial waste heat into electricity.
- What it is
- Thermoelectric conversion turns a temperature difference directly into electricity, using the Seebeck effect. A good thermoelectric material conducts electricity well but heat poorly, and its efficiency is rated by the figure of merit zT. TlCu5Se3 is a newly studied copper chalcogenide whose confined copper motion keeps lattice heat conduction very low.
- Who did it
- The work was done at JNCASR, Bengaluru, an autonomous institute under the Department of Science & Technology, led by Prof. Kanishka Biswas.
- Performance
- The material reaches a thermoelectric figure of merit (zT) of 1.7, among the highest for pristine ternary chalcogenides.
- Mechanism
- Confined, localized disorder of Cu atoms, not long-range liquid-like diffusion, causes strong anharmonicity and wave-like coherence of phonons.
- Method
- The team used the unified formalism of thermal transport, which covers both particle-like phonon propagation and wave-like coherence between phonon branches.
- Seebeck effect
- The Seebeck effect is the generation of voltage across a material from a temperature difference; it underlies thermoelectric generators.
- Old ceiling
- Crystalline solids were limited to a few millivolts per Kelvin; only ionic liquids and gels crossed into that range.
- Material and method
- Thin ScN films were grown on magnesium oxide substrates by ultrahigh-vacuum magnetron sputtering and doped with magnesium to compensate free electrons.
Don’t confuse with Seebeck vs Peltier effect: Seebeck: a temperature difference produces voltage (power generation). Peltier: an electric current produces heating or cooling at a junction (refrigeration).
Don’t confuse with Phonon vs wave-like coherence: Phonons are quantised lattice vibrations that carry heat like particles. In this regime, heat also moves by coherence between different vibrational modes.
Don’t confuse with Seebeck coefficient vs figure of merit zT: The coefficient is voltage per Kelvin. zT rates overall thermoelectric efficiency and also depends on electrical and thermal conductivity.
Science and technology: 57 Prelims questions since 2013; most test the concept behind the news, not the news itself. In Mains, 12 news-triggered questions.
Why it matters
- Efficient thermoelectrics can recover waste heat from power plants, cement and steel units, automobiles and data centres, saving energy and cutting emissions.
- Ultralow thermal conductivity materials also help thermal barrier coatings and quantum technologies.
- Could enable ultrasensitive temperature sensors, thermal imaging and quantum photon detectors built in India.
- Shows engineered disorder as a new route to better solid-state thermoelectrics.
Problems
- Results are laboratory-scale; the material contains thallium, which is toxic, and scaling up and costs are untested.
- Peak zT is only reached over a limited temperature range, so real device efficiency and durability must still be proven.
- Result is from thin films and a preliminary prototype; scale-up and cost are unproven.
- Single-photon detection needs further optimization and cryogenic operation.
Way forward
- Build and test prototype modules, and look for less toxic, abundant alternatives.
- Support materials research and industry pilots for waste-heat recovery.
- Optimize films and test devices for stability and reproducibility.
- Support translation through patents, industry links and national quantum and sensor missions.
Put in your answer
Indigenous research: JNCASR, an autonomous DST institute, shows Indian basic research in materials science reaching high-impact journals such as Science Advances.
Waste-heat uses: The release lists power plants, cement, steel, automobiles, data centres and battery heat management as target sectors.
Indigenous research example: JNCASR (DST) work published in Science, with an Indian patent filed, shows Indian basic research reaching applications.
UPSC’s own questions that come close to this issue, from our Prelims and Mains banks.
No practice question for this one; the card may still help an answer. Why: Science concepts are 57 of 327 Prelims questions, but this is a niche research finding with few testable facts.
Worth revising until Prelims 2028: most news questions come within two years of the event.