Superconductors with respect to electricity manifest zero resistance to electric current. But they are NOT also superconductors with respect to heat. The flip side of electrical superconductivity is electrical superinsulation. Both are low-temperature phenomena, though of course scientists are trying to raise the upper temperature limits. Superinsulators manifest infinite resistance to electric current, i.e., zero electrical conductivity.
QUESTION: Are, or are not, superinsulators with respect to electricity also superinsulators with respect to heat? In other words, do, or do not, superinsulators with respect to electricity also manifest infinite resistance to the flow of heat, i.e., zero thermal conductivity?. If their thermal conductivity is greater than zero, what is it?
Wang, Han, and Zhiyuan Shen. "Optimization Investigation on the Radiation Thermal Conductivity of Nano-Superinsulating Materials." Journal of Computational and Theoretical Nanoscience 14, no. 4 (2017): 1805-1812.
Dear Dr. Azeez Barzinjy,
Thank you very much for this reference.
All the best.
Sincerely yours,
Jack Denur
Dear Dr. Azeez Barzinjy,
I looked up the article that you suggested. Unfortunately, the library at North Texas State University, to which I have online access, doesn't have the journal, so I can't get the full text for free. Most journals charge $30 or so to buy an article, which is reasonable, but this one charges $106 plus tax.
Is the following correct, based on the Abstract of the article?
From the Abstract, it seems that the article discusses "superinsulators" such as aerogels that are useful at ordinary temperatures. The Abstract mentions "aerospace, chemical industry, electric power". Such "superinsulators" are very good but not perfect insulators, and they are not the flip side of superconductors. By contrast, the perfect superinsulators mentioned in my question are the flip side of superconductors, currently existing only at cryogenic temperatures (although of course scientists are trying to raise the upper temperature limit).
Thank you very much once again.
All the best.
Sincerely yours,
Jack Denur
Electrical resistance and thermal conductivity are related in solids. Good electrical conductors are also good thermal conductors. Therefore, one expects that superinsulators should also give large resistance to the flow of heat.
There can never be zero thermal conductivity in a solid, since bonded atoms will always allow for vibrations to travel between them. The theorized lower limit is when the phonon scattering length approaches the interatomic spacing, the so called 'amorphous limit'.
Thank you very much, Snehadri Ota and Stephen R. Boona, for your very informative and very helpful replies.
To Snehardi Ota: It is true that electrical and thermal conductivity (or resistivity) are related in solids. But there are nonetheless major differences. At room temperature, the best electrical conductors are about 10^25 times as good as the worst ones, but the best heat conductors are only about 10^5 times as good as the worst ones. Even if superinsulators --- PERFECT insulators --- with respect to electricity are GOOD insulators with respect to heat, would they be LESS THAN PERFECT insulators with respect to heat? Superconductors --- PERFECT conductors --- with respect to electricity are LESS THAN PERFECT (perhaps not even good) conductors with respect to heat.
The 'exact reason' for thermal conductivity (or resistivity) may be different from material to material and thermodynamic parameters such as temperature or pressure. For a given mechanism, what are the additional improvements needed to understand an observation, can be of interest.
- Badges
- Science topic
- Similar topics
- Entomology
- Resistance