Researchers produce insulation with lowest thermal conductivity ever

December 14, 2006

A new insulation material with the lowest thermal conductivity ever measured for a fully dense solid has been created at the University of Oregon and tested by researchers at three other U.S. institutions. While far from having immediate application, the principles involved, once understood, could lead to improved insulation for a wide variety of uses, the scientists say.

In a paper published online Dec. 14 on Science Express, in advance of regular publication in the journal Science, the scientists describe how they used a novel approach to synthesize various thicknesses of tungsten diselenide. This effort resulted in a random stacking of tungsten-diselenide planes (WSe2), possibly leading to a localization of lattice vibrations.

The resulting synthesized material, they report, resulted in thermal conductivity -- the rate at which heat flows through a material -- 30 times smaller than that for single-crystal WSe2 and a factor six smaller that the minimum level predicted by theoretical computations for the cross-plane thin films used in the experiments.

Surprisingly, creating a fully disordered structure by bombarding the films with ions to destroy the order in the two-dimensional planes actually increases thermal conductivity, said David C. Johnson, a professor of chemistry at the University of Oregon and member of the UO Materials Science Institute.

"The reason for the extraordinarily low thermal conductivity that we've now achieved is an unusual structure which is crystalline in two directions but has a subtle rotational disorder in the direction of low-heat conduction," Johnson said.

The material prepared in Johnson's lab "is the closest thing that anyone has found to making a dense solid into a perfect thermal insulator," said co-author and corresponding investigator David G. Cahill, a professor of materials science and engineering at the University of Illinois at Urbana-Champaign. "This material would not be practical for insulating a refrigerator, the wall of a house or parts inside a turbine engine, but the new physical properties displayed by this material might some day point the way toward methods of creating more effective practical insulations."

The approach is a new alternative to one described by Cahill and others in separate journals in the last two years in which researchers reduced minimum thermal conductivity by manipulating thin films of metals and oxides by adjusting interfaces of the materials by only a few nanometers.

"Thermal conductivity is an important property in both conserving energy and in converting between forms of energy," Johnson said. "Obtaining low thermal conductivity in a thermoelectric material, which converts temperature gradients into electrical energy, increases efficiency."

The properties of Johnson's material were measured in Cahill's Illinois laboratory. The structure was analyzed at the Argonne National Laboratory in Argonne, Ill. Computational simulations and molecular modeling of the layered crystals was carried out by researchers at Rensselaer Polytechnic Institute (RPI) in Troy, N.Y.
Co-authors Pawel Keblinski and Arun Bodapati, both at RRI, said that the observed ultra-low thermal conductivity is not limited to tungsten diselenide and likely could be applied to a wide variety of disordered layered crystals.

Other co-authors were Catalin Chiritescu, a student in Cahill's lab at the University of Illinois, Ngoc Nguyen, a doctoral student in Johnson's UO lab, and Paul Zschack of Argonne National Laboratory's Advanced Photon Source.

Johnson also is the founder of the Center for Advance Materials Characterization in Oregon (CAMCOR) and the co-director of research at the Oregon Nanoscience and Microtechnologies Institute. ONAMI is an Oregon Signature Research Center made up of collaborating researchers from the UO, Oregon State University, Portland State University and the Pacific Northwest National Laboratory who pursue fundamental and applied research projects with industry in the Northwest.

The Office of Naval Research and the U.S. Department of Energy provided funding for various components of the project.

Media Contact: James Kloeppel, physical science editor, University of Illinois at Urbana-Champaign, 217-244-1073, or; Jason Gorss, Office of Media Relations, Rensselaer Polytechnic Institute, 518-276-6098,

Sources: David C. Johnson, professor of chemistry, UO Materials Science Institute, 541-346-4612,; David G. Cahill, Willett Professor of Engineering, professor of materials science and engineering, University of Illinois, 217-333-6753,

Links: Johnson,; Cahill,

University of Oregon

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 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