Thermodynamic properties of calcium-magnesium alloys determined by emf measurements

Jocelyn M. Newhouse, Sophie Poizeau, Hojong Kim, Brian L. Spatocco, Donald R. Sadoway

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Abstract

The thermodynamic properties of calcium-magnesium alloys were determined by electromotive force (emf) measurements using a Ca(in Bi) CaF2Ca(in Mg) cell over the temperature range 713-1048 K. The activity and partial molar Gibbs free energy of calcium in magnesium were calculated for nine Ca-Mg alloys, calcium mole fractions varying from xCa = 0.01 to 0.80. Thermodynamic properties of magnesium in calcium and the molar Gibbs free energy of mixing were estimated using the Gibbs-Duhem relationship. In the all-liquid region at 1010 K, the activity of calcium in magnesium was found to range between 8.8 × 10-4 and 0.94 versus pure calcium. The molecular interaction volume model (MIVM) was used to model the activity coefficient of Ca and Mg in Ca-Mg liquid alloys. Based on this work, Ca-Mg alloys show promise as the negative electrode of a liquid metal battery in which calcium is the itinerant species: alloying with Mg results in both a decrease in operating temperature and suppression of Ca metal solubility in the molten salt electrolyte.

Original languageEnglish (US)
Pages (from-to)293-301
Number of pages9
JournalElectrochimica Acta
Volume91
DOIs
StatePublished - Feb 28 2013

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All Science Journal Classification (ASJC) codes

  • Chemical Engineering(all)
  • Electrochemistry

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