Hydrogen solid solution thermodynamics of V1−xAlx (x: 0, 0.18, 0.37, 0.52) alloys

• Published in: International journal of hydrogen energy Vol. 38; no. 23; pp. 9928 - 9934
• Main Authors: Kumar, Sanjay, Sonak, Sagar, Krishnamurthy, Nagaiyar
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 06.08.2013; Elsevier
• Subjects: Alternative fuels. Production and utilization; Applied sciences; Electrical resistivity; Energy; Enthalpy; Entropy; Exact sciences and technology; Fermi energy; Fuels; Hydrogen; Solid solubility; Entropy; Electrical resistivity; Solid solubility; Enthalpy; Fermi energy; Thermodynamics; Hydrogen; Alloys; Solubility; Electric resistivity; Solid solution
• ISSN: 0360-3199; 1879-3487
• DOI: 10.1016/j.ijhydene.2013.05.122

Thermodynamic parameters such as enthalpy and entropy of the vanadium–hydrogen solid solution are investigated as a function of aluminum content using hydrogen solubility data and the Sievert's constant. The enthalpy decreases with increase in the aluminum content. Entropy shows anomalous behavior as it first increases with the aluminum content for V1−xAlx (x: 0, 0.18, 0.37) but then substantially decreases for V0.48Al0.52. The lattice parameters and the electrical resistivity of the alloys are calculated to explain the mechanical and electronic effects on the thermodynamic parameters. It is found that the electrical resistivity of vanadium systematically decreases and the lattice constant increases with increase in aluminum content. The hardness of the alloys increases with aluminum which indicates that aluminum hardens the vanadium by simple solid solution effect. The variation of enthalpy and entropy is explained on the basis of change in Fermi energy level of the host matrix vanadium, the strong bonding nature of V–Al in the alloy and increased activity of hydrogen due to aluminum in the alloy. •Enthalpy of V–H solid solution increases with aluminum.•Entropy of V–H solid solution decreases with aluminum.•Increase in the Fermi energy level of vanadium could be one of the reasons.•Sievert's law could be used to calculate the entropy & enthalpy of V–H system.