A replacement for AGOT graphite?

Abstract

Pitch bonded graphites are among the best known thermal insulators at sub-Kelvin temperatures. At higher temperatures, however, they are good conductors. Graphite supports can therefore be used to allow a relatively rapid cool-down of structures which must be thermally isolated when cold. The low temperature conductivity of graphites varies by many orders of magnitude depending on the manufacturing process. AGOT graphite is known to be a very good insulator, but is no longer commercially available. We suggest a replacement, and present thermal conductivity measurements demonstrating its suitability.

Thermal conductivity of thermally-isolating polymeric and composite structural support materials between 0.3 and 4K

“…An upper-and lower-limit to the conductivity of Poco Graphite AXM-5Q is reported in Woodcraft et al [18]. The limits of Woodcraft et al [18] are consistent with our measurements.…”

“…An upper-and lower-limit to the conductivity of Poco Graphite AXM-5Q is reported in Woodcraft et al [18]. The limits of Woodcraft et al [18] are consistent with our measurements. We also observe the leveling-off of the thermal conductivity at the low-temperature end.…”

“…It is worth noting that the graphite sample is the only material we tested that has an effective index that rises significantly with increasing temperature rather than falling. As noted in Woodcraft et al [18], this feature makes the material attractive for use as a passive heat switch. With a room-temperature conductivity of around 90 W/m K, the ratio of room-temperature to T = 1.4 K conductivity is ∼34,000 for AXM-5Q.…”

“…We measure a sample of graphite rod from Poco Graphite Inc. 6 The type of graphite measured is the same as that tested in Woodcraft et al [18] (industrial grade AXM-5Q). This graphite has a particle size of 5 microns and an apparent density of 1.73 g/cc.…”

Electronic nematicity and its relation to quantum criticality in Sr3Ru2O7 studied by thermal expansion

“…In order to improve thermal equilibrium at the lowest temperatures, the sample is thermally decoupled from the dilatometer by insulator parts made from POCO AXM-5Q graphite [15] and thermally anchored by a silver cylinder 1 which is directly connected to the temperature stage with a silver loom. The bottom graphite piece plugs into the dilatometer base with a square end and doubles as a sample holder.…”