A basic tenet of college physics is that as pressure increases, thermal conductivity—a material's ability to conduct heat—increases, too, because atoms that are squeezed together interact more.
More than a century of research has confirmed this rule. But engineers have now found an exception: when they applied intense pressure to boron arsenide, a recently discovered semiconductor material, thermal conductivity decreased. The finding, described in Nature, challenges established theory and potentially upends current models of how substances behave under extreme conditions.
“Now that we've made this first discovery, we think this can't be the only material with abnormal behavior,” says study senior author Yongjie Hu, a chemist and mechanical engineer at the University of California, Los Angeles. If other substances show this property, “the established understanding of thermal conductivity might not be correct.”
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