Graphite specific heat capacity

Below the Debye temperature, only the acoustic modes contribute to heat capacity. It turns out that within a plane there is a quadratic correlation to the temperature, whereas linear behavior is observed for a perpendicular orientation. These assumptions hold for graphite, which indeed exhibits two acoustic modes within its layers and one at right angles to them. In carbon nanotubes, on the other hand, there are four acoustic modes, and they consequently differ from graphite in their thermal properties. StiU at room temperature enough phonon levels are occupied for the specific heat capacity to resemble that of graphite. Only at very low temperatures the quantized phonon structure makes itself felt and a linear correlation of the specific heat capacity to the temperature is observed. This is true up to about 8 K, but above this value, the heat capacity exhibits a faster-than-Unear increase as the first quantized subbands make their contribution in addition to the acoustic modes. 

The specific heat capacity of graphite is taken as the constant value Cc = 8.5 J/ (mol K). All the other heat capacities depend on temperature. In order to determine them recourse is had to the information of Sect. 2.1.1.8. Use is made of the facts that the integral of Cp over temperature is the enthalpy and that the relationship... 

Specimens with a dimension of 10 mm in diameter and 2-3 mm in thickness were cut from the CS-SPSed discs, and were polished using emery paper until No. 1200. Prior to measurement, a thick layer of colloidal graphite was sputter-coated to the surface of the specimen to enhance absorption of the flash energy. The thermal diffusivity and specific heat capacity were measured by the laser-flash method... 

Figure 8. Typical curves for rate of release of stored energ) for a number of blocks in Pile 2 channel 32/57 TR. Note that five out of six curves exceed the specific heat capacity of the graphite and thus that a spontaneous energy release is theoretically possible.

Specific heat capacity J K kg- 1013 959 (30% glass fiber) 963 (30% carbon fiber) 1005 (graphite) ... 

Regress a third order polynomial (cp = a + bT -h cT + dT ) to results of the equation for the heat capacity at constant pressure for graphite reported in Rutland, A.T.D. and Maddison, RJ. (1973). The specific heat of graphite an evaluation of measurements. J. NucL Mater., 49, 45-56 ... 

Figure 11.15 Specific heat (heat capacity per gram) versus temperature T for solids diamond ( ), graphite (o), and fuiierenes ( ). This iog-iog plot emphasizes the behavior at iow temperatures. The Einstein modei of independent oscillators ( ) characterizes fuiierenes from about T = 5 K - 100 K, but the more...

Experimental studies including neon or helium as adsorbates require temperatures lower than 20 K, so that fewer results have been obtained. Thorny et al. [50] performed what is considered to be the first significant experimental study of neon on grafoil, obtaining the adsorption isotherms. The heat capacity was measured by Antoniou [51], with graphite as the adsorbent, whereas specific heat measurements were performed by Huff and Dash [52] and De Souza et al. [53], with grafoil as the adsorbent. Subsequent studies are focused on the phase transitions and will be commented on in Section II.A. 

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