A study of temperature and pressure-induced structural and electronic changes in SbCl 5 intercalated graphite: Part III.
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E. McRae, M. Lelaurain, and J. F. Mareche Universite de Nancy I, Laboratoire de Chimie du Solide Mineral, U.R.A. C.N.R.S. 158, Service de Chimie Minerale Appliquee, B.P. 239, 54506 Vandoeuvre-les-Nancy Cedex, France (Received 2 March 1994; accepted 31 October 1994)
We present experimental data for the c-axis electrical resistivity of SbCl5 intercalated graphite between 20 and 300 K. The data are analyzed together with our previous results for these and other samples [O.E. Andersson et al, J. Mater. Res. 7, 2989 (1992)]. Before the analysis, we correct the experimental data to constant volume, as assumed by theorists. We show that the correction factor is much larger for these materials than for normal metals. Although the original data showed significant nonlinearities with T, the corrected data are linear in T to within the experimental accuracy for low-stage compounds below the intercalate crystallization temperature. We compare our results with several models and conclude that both the temperature dependence, the pressure dependence, and the relative changes in the in-plane and c-axis resistivities associated with intercalate crystallization can be best described by a band conduction model.
I. INTRODUCTION 12
The present paper follows upon two others dealing, respectively, with the preparation and structural characterization1 of SbCl5 graphite intercalation compounds (GIC's) and the c-axis resistivity2 pc at pressures (j>) up to 0.7 GPa and at temperatures T between 40 and 300 K. These will henceforth be referred to as papers I and II, respectively. Although we will here present some additional results for pc as a function of T and p, and data for pc corrected to constant c-axis lattice parameter, our primary purpose with this third article is to analyze and discuss the results in papers I and II, and to underline the interrelations among chemistry, structure, and c-axis transport. It is not necessary to include here all the references that have already been given in papers I and II; we will include only those that become specifically necessary. The paper is organized as follows: In Sec. II, we briefly summarize the current status as regards the theory of c-axis transport mechanisms in graphite and its intercalation compounds. This is presented in some detail since we have recently shown that many conclusions based on results concerning the SbCls GIC family apply to a vast range of GIC's. 3 Section III summarizes some results newer than those presented in papers I and II. The main body of the paper is contained in the discussion in Sec. IV, and our overall conclusions are drawn in Sec. V. 436 http://journals.cambridge.org
J. Mater. Res., Vol. 10, No. 2, Feb 1995 Downloaded: 18 Mar 2015
II. THEORETICAL BACKGROUND: C-AXIS CONDUCTIVITY The mechanism of c-axis conductivity has been a controversial subject over several decades even for unintercalated ("pure") graphite.4 8 The open questions and the lines of development have dealt with several different features, the most important among them being (i) the differ
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