Low temperature anomalies in thermoelectricity of highly oriented graphite in relation to sample quality

✍ Scribed by Y. Hishiyama; A. Ono

• Publisher: Elsevier Science
• Year: 1985
• Tongue: English
• Weight: 397 KB
• Volume: 23
• Category: Article
• ISSN: 0008-6223
• DOI: 10.1016/0008-6223(85)90039-9

✦ Synopsis

The thermoelectric power S of various specimens of kish graphite and highly oriented pyrolytic graphite was studied in relation to the sample quality at temperatures (7') between 1.3 and 280 K. The resistivity ratio between 300 and 4.2 K used as a measure of structural perfection ranges from 1.6 to 35.8. A thermoelectric transport coefficient pyt(0) has been determined for specimens with resistivity ratios of 10.0 and 35.8. S as well as pT1(0) show a common behavior as follows; a negative dent at about 3.0-4.4 K, a sharp peak at about 6.5-14 K, a pronounced negative dip around 20-37 K and a broad peak somewhere between 125 and 160 K. The dent and peak depend strongly on the quality of the specimen: The former is a new finding and may be due to some unknown type of the phonon drag effect, while the latter is due to the two-stage phonon drag effect proposed by Sugihara et al. based on their own observations.