Pippard relations for cubic gauche nitrogen

Abstract

The Pippard relations (CP vs. P and P vs. T) are examined at various temperatures up to 1200 K at zero pressure (P = 0) for the cubic gauche nitrogen. The specific heat (CP) is related to the thermal expansion (P) and the P is also related to the isothermal compressibility (T) as the Pippard relations for this solid structure. For those relations, experimental data are used from the literature. It is found that the variation of the CP with the P and P with the T is linear. Using the linear relations dP/dT is predicted, which can be compared with the experimental measurements in the P-T phase diagram of cubic gauche nitrogen.

Calculation of the Thermodynamic Quantities for Cubic Gauche Nitrogen (cg-N)

“…We have given our relations (Eqs. 1,6 and 7) with the thermodynamic relations (Eq.4) for the cg-N phase in our earlier study [20].…”

“…We have also given Eqs. ( 8) and (11) for the cg-N structure in our previous study [20]. Volume can be expressed as a function of pressure as…”

“…Values of the coefficients for the volume V(T) and for the bulk modulus B(T) according to Eqs. ( 1) and (6), which were fitted to the thermal expansivity V0(T) and the bulk modulus K0 (T) data [18], respectively, at P=0 for the cg-N, as also given in our previous study [20].…”

“…From this point of view, by using some literature data, those thermodynamic quantities of interest are calculated at various temperatures and pressures for the cg-N structure. Regarding some earlier studies [18,20], the present work gives the calculation method of those thermodynamic quantities at higher pressures as well as their temperature dependence at zero pressure in the cg-N structure. Considering the pressure effects which changes the critical behavior of those thermodynamic quantities ( mainly κT, αp and B) at various temperatures in the cg-N phase, their pressure dependence has not been investigated extensively in the earlier works [18,20].…”

“…Regarding some earlier studies [18,20], the present work gives the calculation method of those thermodynamic quantities at higher pressures as well as their temperature dependence at zero pressure in the cg-N structure. Considering the pressure effects which changes the critical behavior of those thermodynamic quantities ( mainly κT, αp and B) at various temperatures in the cg-N phase, their pressure dependence has not been investigated extensively in the earlier works [18,20]. The pressure dependence as studied here, is also the principal improvement and contributions to the thermodynamic properties of the cg-N structure.…”