Thermodynamic properties of silicides. II. Heat capacity at temperatures T from 5.9 K to 341 K and derived thermodynamic properties to T = 1200 K of tungsten disilicide: WSi2.06

✍ Scribed by Jane E. Callanan; Ron D. Weir; Edgar F. Westrum Jr.

• Publisher: Elsevier Science
• Year: 1993
• Tongue: English
• Weight: 316 KB
• Volume: 25
• Category: Article
• ISSN: 0021-9614
• DOI: 10.1006/jcht.1993.1140

✦ Synopsis

The heat capacity of tungsten disilicide (\mathrm{WSi}{2.06}) was measured over the temperature range (5.9<(T / K)<341) using adiabatic calorimetry. Our results show that neither a phase transition nor anomalies are present. A contribution from the electronic molar heat capacity is present and (\gamma=(1.33 \pm 0.25) \mathrm{mJ} \cdot \mathrm{K}^{-2} \cdot \mathrm{mol}^{-1}). For the lattice, the Debye characteristic temperature (\Theta{\mathrm{D}}^{C}=(317.8 \pm 3.3) \mathrm{K}). From our results, the standard molar entropy (S_{\mathrm{m}}^{o}\left(\mathrm{WSi}{2.06}\right.), cr, (\left.298.15 \mathrm{~K}\right)=) ((68.43 \pm 0.17) \mathrm{J} \cdot \mathrm{K}^{-1} \cdot \mathrm{mol}^{-1}). On the basis of this result, the standard molar Gibbs free energy of formation (\Delta{\mathrm{f}} G_{\mathrm{m}}^{\circ}\left(\mathrm{WSi}_{2.06}, \mathrm{cr}, 298.15 \mathrm{~K}\right)=-(79.5 \pm 5.5) \mathrm{kJ} \cdot \mathrm{mol}^{-1}). Heat capacities derived from drop calorimetry at (T=460 \mathrm{~K}) together with those reported in this work allowed standard molar thermodynamic functions to be presented at selected temperatures from (5 \mathrm{~K}) to (1200 \mathrm{~K}).