ELECTRICAL-RESISTIVITY OF HIGHLY CRYSTALLIZED KISH GRAPHITE

We obtained large and highly crystallized kish graphite flakes and measured the temperature dependence of the in-plane electrical resistivity for the specimens with the rho-300K/rho-4.2K values of 56 and 106 at temperatures between 1.28 and 300 K. The temperature-dependent component of the resistivity rho(T) was examined precisely, particularly at low temperatures. Below about 5 K, rho(T) is proportional to T2, then increases faster to nearly T3 (rho(T) is-proportional-to T2.7) to about 15 K with increasing T. This is the intrinsic behavior of rho(T) for graphite crystal because of high crystallinity of the present specimens. The T2.7 dependence in the temperature range 5 approximately 15 K is due to the scattering of carriers by the out-of-plane phonons, whereas the T2 dependence at temperatures below about 5 K is attributed to the electron-hole scattering as described by Morelli and Uher.