The new superlattice material, Bi4O4SeCl2, developed by a team of scientists from the United Kingdom and France, combines two different arrangements of atoms that were each found to slow down the speed at which heat moves through the structure of a solid.
“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 senior author Professor Matt Rosseinsky, a researcher in the Department of Chemistry at the University of Liverpool.
“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.”
Professor Rosseinsky and colleagues identified the mechanisms responsible for the reduced heat transport in two components, BiOCl and Bi2O2Se, by measuring and modeling the thermal conductivities of their structures.
“Combining these mechanisms in a single material is difficult, because we have to control exactly how the atoms are arranged within it,” they said.
“Intuitively, we would expect to get an average of the physical properties of the two components.”
“By choosing favorable chemical interfaces between each of these different atomic arrangements, we experimentally synthesized a material that combines them both.”
The new material, with two combined arrangements, has an extremely low thermal conductivity of 0.1 W/K*m at room temperature — much lower than either of the parent materials with just one arrangement.
This unexpected result shows the synergic effect of the chemical control of 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.
The development of new and more efficient thermoelectric materials, which can convert heat into electricity, is considered a key source of clean energy.
“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 Dr. Jon Alaria, a researcher in the Department of Physics at the University of Liverpool.
“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.”
The team’s work was published in the journal Science.
Quinn D. Gibson et al. Low thermal conductivity in a modular inorganic material with bonding anisotropy and mismatch. Science, published online July 15, 2021; doi: 10.1126/science.abh1619