THERMAL-CONDUCTIVITY AND HEAT-CAPACITY OF SOLID-PHASES OF BENZENE UNDER PRESSURE

Using the transient hot-wire method, simultaneous measurements of the thermal conductivity, A, and the heat capacity per unit volume, pcP, were made for solid phases I and II of benzene (C6H6). Data were obtained over the temperature range 105 K to 375 K, and at pressures up to 2.4 GPa. At 300 K, the I →II transition was sluggish, so phase I could be retained over a pressure range where it was metastable with respect to phase II. At about 1-2 GPa and 375 K, A for phase II is detectably greater than for phase I, but at 300 K the two values are almost equal. The value of cp for phase I was found to decrease by about 10 per cent over the range 0-1 GPa and to remain essentially constant at higher pressures. Values of cp in phases I and II were found to be equal at all temperatures. The temperature and volume dependences of A are discussed in relation to current theoretical ideas. © 1979 Taylor & Francis Group, LLC.