Anomalous heat capacity and phase transition of graphite-ICl intercalation compounds

✍ Scribed by K. Tashiro; M. Saito; T. Tsuzuku

• Publisher: Elsevier Science
• Year: 1985
• Tongue: English
• Weight: 692 KB
• Volume: 23
• Category: Article
• ISSN: 0008-6223
• DOI: 10.1016/0008-6223(85)90228-3

✦ Synopsis

By

means of alternating current calorimetry and X-ray diffraction, a study has been made of the phase transition behavior of graphite-ICl intercalation compounds slowly heated from 290 to 340 K. The heat capacity vs. temperature plots exhibit A-type anomalies at 305 f I, 312 5 1 and 315 + 1 K. X-ray diffraction indicates that abrupt expansion of the c-axis occurs also near 305, 31 I and 315 K, when the first-to-second, second-to-third and third-to-fourth or fifth stage changes, respectively, occurring in the subsequent temperature ranges are initiated. Each A-type anomaly seems to represent the two-dimensional order-disorder transition of ICI layers taking place prior to the stage change. In order to account for the repetition of the orderdisorder transition at different temperatures. it is proposed that deintercalation and restabilization of ICI layers occur alternatively during the slowly proceeding stage changes.