Using the right chemistry, it is possible to combine two different atomic arrangements (yellow and blue slabs) that provide different mechanisms for slowing down the motion of heat through a solid. This strategy has been used to design an inorganic material with the lowest thermal conductivity ever reported. Image: University of Liverpool.A collaborative research team has discovered a new inorganic material with the lowest thermal conductivity ever reported. This discovery paves the way for the development of new thermoelectric materials that will be critical for a sustainable society.
Reported in a paper in Science, this discovery represents a breakthrough in the control of heat flow at the atomic scale, achieved by materials design, and offers fundamental new insights into the management of energy. This new understanding will accelerate the development of new materials for converting waste heat to power and for the efficient use of fuels.
Approximately 70% of all the energy generated in the world is wasted as heat. Low thermal conductivity materials are essential to reduce and harness this waste heat. The development of new and more efficient thermoelectric materials, which can convert heat into electricity, is considered a key source of clean energy.
Led by Matt Rosseinsky and Jon Alaria at the University of Liverpool in the UK, the research team designed and synthesized the new inorganic material so that it combined two different arrangements of atoms that each slow down the speed at which heat moves through the structure of a solid. The team identified the mechanisms responsible for the reduced heat transport in each of these two arrangements by measuring and modelling the thermal conductivities of two structures, each of which contained one of the required arrangements.
Combining these mechanisms in a single material is difficult, because researchers have to control exactly how the atoms are arranged within it. Intuitively, scientists would expect to get an average of the physical properties of the two components. However, by choosing favourable chemical interfaces between each of these different atomic arrangements, the team experimentally synthesized a material that combines them both.
The new material, with two combined arrangements, has a much lower thermal conductivity than either of the parent materials with just one arrangement. This unexpected result shows the synergic effect of chemically controlling atomic locations in the structure, and is the reason why the properties of the whole structure are superior to those of the two individual parts. If the thermal conductivity of steel is given a value of 1, then a titanium bar is 0.1, water and a construction brick are 0.01, the new material is 0.001 and air is 0.0005.
"The material we have discovered has the lowest thermal conductivity of any inorganic solid and is nearly as poor a conductor of heat as air itself," said Rosseinsky. "The implications of this discovery are significant, both for fundamental scientific understanding and for practical applications in thermoelectric devices that harvest waste heat and as thermal barrier coatings for more efficient gas turbines."
"The exciting finding of this study is that it is possible to enhance the property of a material using complementary physics concepts and appropriate atomistic interfacing," said Alaria. "Beyond heat transport, this strategy could be applied to other important fundamental physical properties such as magnetism and superconductivity, leading to lower energy computing and more efficient transport of electricity."
This story is adapted from material from the University of Liverpool, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.