Record-setting thermoelectric figure of merit achieved for metal oxides

December 22, 2020

Scientists at Hokkaido University have developed a layered cobalt oxide with a record-setting thermoelectric figure of merit, which can be used to enhance thermoelectric power generation.

Waste heat is a highly promising source of renewable energy; however, the efficiency of using heat to generate energy has historically been much lower than hydroelectric, wind or solar power. While there are a number of materials that can be used for the generation of energy from waste heat, they all suffer from various issues ranging from low stability to low efficiency. Nevertheless, the fact that a large number of industries generate copious amounts of waste heat have driven research into this field.

A team of scientists led by Professor Hiromichi Ohta at the Research Institute for Electronic Science (RIES), Hokkaido University, has recently developed a layered cobalt oxide with a record-setting thermoelectric figure of merit for metal oxides at room temperature. Their findings were published in the journal Journal of Materials Chemistry A.

Thermoelectric conversion is driven by the Seebeck effect: when there is a temperature difference across a conducting material, an electric current is generated. Historically, the efficiency of heat-to-electricity conversion of metal oxides was very low; however, metal oxide-based thermoelectric devices are highly desired due to their environmental compatibility. The thermoelectric conversion efficiency of a device depends on a key factor called the thermoelectric figure of merit (ZT).

Hiromichi Ohta's group has developed a layered cobalt oxide that exhibits a high ZT and is stable across a range of operating temperatures. Well-known sodium-cobalt oxide, where sodium and cobalt oxide layers alternate, shows a very low ZT of around 0.03, but the material developed by Ohta's group achieved a ZT of 0.11. The group replaced the sodium by other alkali or alkaline earth metals: calcium, strontium, and barium.

The layered barium-cobalt oxide material exhibited a record-setting ZT of 0.11 at room temperature. The increase in ZT is directly caused by the decreased thermal conductivity of barium. As the scientists hypothesized, the greater the atomic mass, the lower the thermal conductivity, resulting in higher ZT. This is due to the fact that heavier atoms suppress the vibrations in the cobalt oxide layers caused by heating. Further research is required to optimize the material's composition for higher efficacy and stability, as well as determining the most useful practical applications.

Hiromichi Ohta is the head of the Laboratory of Functional Thin Film Materials at the RIES, Hokkaido University. His areas of research include Thermoelectrics, Thermopower modulation, Optoelectronics and Iontronics.
-end-


Hokkaido University

Related Thermal Conductivity Articles from Brightsurf:

Clemson researchers decode thermal conductivity with light
Clemson researchers examine a highly efficient thermoelectric material in a new way - by using light.

Collaboration sparks new model for ceramic conductivity
As insulators, metal oxides - also known as ceramics - may not seem like obvious candidates for electrical conductivity.

Topology-optimized thermal cloak-concentrator
Cloaking a concentrator in thermal conduction via topology optimization. A simultaneous cloaking and concentrating of heat flux is achieved through topology optimization, a computational structural design methodology.

Investigating a thermal challenge for MOFs
New research led by an interdisciplinary team across six universities examines heat transfer in MOFs and the role it plays when MOFs are used for storing fuel.

Thermal manipulation of plasmons in atomically thin films
Nanoscale photothermal effects can induce substantial changes in the optical response experienced by the probing light, thus suggesting their applications in all-optical light modulation.

Making plastic more transparent while also adding electrical conductivity
In an effort to improve large touchscreens, LED light panels and window-mounted infrared solar cells, researchers at the University of Michigan have made plastic conductive while also making it more transparent.

Extremely low thermal conductivity in 1D soft chain structure BiSeX (X = Br, I)
Researchers found a new sort of simple one-dimensional (1D) crystal structured bismuth selenohalides (BiSeX, X = Br, I) with extremely low thermal conductivity.

Minimizing thermal conductivity of crystalline material with optimal nanostructure
Japanese researchers successfully minimized thermal conductivity by designing, fabricating, and evaluating the optimal nanostructure-multilayer materials through materials informatics (MI), which combines machine learning and molecular simulation.

Scientists measured electrical conductivity of pure interfacial water
Skoltech scientists in collaboration with researchers from the University of Stuttgart, the Karlsruhe Institute of Technology and the Russian Quantum Center achieved the first systematic experimental measurements of the electrical conductivity of pure interfacial water, hence producing new results significantly extending our knowledge of interfacial water.

Atomic magnetometer points to better picture of heart conductivity
Mapping the electrical conductivity of the heart would be a valuable tool in diagnosis and disease management, but doing so would require invasive procedures, which aren't capable of directly mapping dielectric properties.

Read More: Thermal Conductivity News and Thermal Conductivity Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.