# Low temperature transport properties of pyrolytic graphite sheet

## TL;DR

This study measures the thermal and electrical transport properties of uncompressed pyrolytic graphite sheet across a wide temperature range, highlighting its high conductivity and potential as a lightweight thermal link.

## Contribution

It provides detailed transport measurements of uPGS, demonstrating its superior conductivity compared to exfoliated graphite and establishing a relationship between thermal and electrical conductivities.

## Key findings

- uPGS has higher conductivity than Grafoil due to high crystallinity.
- Thermal conductivity exceeds copper and aluminum above 60 K.
- A general relationship between thermal and electrical conductivities in graphite materials.

## Abstract

We have made thermal and electrical transport measurements of uncompressed pyrolytic graphite sheet (uPGS), a mass-produced thin graphite sheet with various thicknesses between 10 and 100 {\mu}m, at temperatures between 2 and 300 K. Compared to exfoliated graphite sheets like Grafoil, uPGS has much higher conductivities by an order of magnitude because of its high crystallinity confirmed by X-ray diffraction and Raman spectroscopy. This material is advantageous as a thermal link of light weight in a wide temperature range particularly above 60 K where the thermal conductivity is much higher than common thermal conductors such as copper and aluminum alloys. We also found a general relationship between thermal and electrical conductivities in graphite-based materials which have highly anisotropic conductivities. This would be useful to estimate thermal conductance of a cryogenic part made of these materials from its electrical conductance more easily measurable at low temperature.