Thermochemical and pressure-volume-temperature systematics of data on solids, examples: Tungsten and MgO

摘要: Data systematization using the constraints from equation $$Cp = Cv + \alpha _P {}^2V_T K_T T$$ where Cp, Cv, αp, KT and V are respectively heat capacity at constant pressure, volume, isobaric thermal expansion, isothermal bulk modulus molar has been performed for tungsten MgO. The data $$K_T (W) 1E - 5/(3.1575E 12 1.6E 16T 3.1E 20T^2 )$$ $$\alpha 9.386E 6 5.51E 9T$$ $$C_P 24.1 3.872E 3T 12.42E 7T^2 63.96E 11T^3 89000T^{ 2} $$ $$K_T (MgO) 1/(0.59506E 0.82334E 10T 0.32639E 13T^2 0.10179E 17T^3 $$ $$\alpha 0.3754E 4 0.7907E 8T 0.7836/T^2 0.9148/T^3 $$ $$C_P 43.65 0.54303E 2T 0.16692E7T^{ 0.32903E4T^{ 1} 5.34791E 8T^2 $$ For calculation of pressure-volume-temperature relation, a high temperature form Birch-Murnaghan is proposed $$P 3K_T (1 2f)^{5/2} 2\xi f)$$ Where 1/(b_0 b_1 T b_2 T^2 b_3 T^3 )$$ $$f (1/2)\{ [V(1,T)/V(P,T)]^{2/3} 1\} $$ $$\xi ({3 \mathord{\left/ {\vphantom {3 4}} \right. \kern-\nulldelimiterspace} 4})[K'_0 K'_1 \ln ({T {T {300}}} {300}}) 4]$$ where in turn $$V(1,T) V_0 [\exp (\int\limits_{300}^T {\alpha dT)]} $$ .