Thermal conductivity of wood at low temperatures

Abstract

The thermal conductivity of oak and maple was investigated in the temperature range 0.02-1 K. For both samples a power law κ = λT n was determined, with n = 2.7 ± 0.4 and λ = (9.3 ± 1.9) × 10 −3 [W K −(n+1) m −1]. Hence, the thermal conductivity of hardwoods behaves very similarly in terms of magnitude and temperature dependence to insulators like Al 2O 3 or polyimids. The intrinsic heat release of wood was estimated to be ⪡40 pW cm −3 after a week of operation below 1 K. Therefore, hardwood turns out to be a very reasonable substitute for plastics or Al 2O 3 in cases where easy machining, good mechanical strength and very low thermal conductivity are required for parts used in low temperature experiments. Maple is favoured because of the smoother surface structure obtainable after machining.