Thermodynamic properties of Sr-Sb alloys via emf measurements using solid CaF2-SrF2 electrolyte

• Published in: Electrochimica acta 2019-05, Vol.305 (C), p.547-554
• Main Authors: Smith, Nathan D., Orabona, Nicole, Lichtenstein, Timothy, Gesualdi, Jarrod, Nigl, Thomas P., Kim, Hojong
• Format: Article
• Language: English
• Subjects: Calcium fluoride; Chemical compounds; Differential scanning calorimetry; Electric potential; Electrochemical cells; Electromotive forces; Emf method; Intermetallic compounds; Organic chemistry; Phase diagrams; Phase transitions; Sr-Sb alloys; Sr-Sb phase diagram; Strontium base alloys; Strontium fluorides; Temperature; Thermodynamic properties; X-ray diffraction
• ISSN: 0013-4686; 1873-3859
• DOI: 10.1016/j.electacta.2019.02.124

The thermodynamic properties of Sr-Sb alloys were determined by electromotive force (emf) measurements to understand the solution and phase behavior of Sr in Sb. A Sr(s) | CaF2-SrF2 | Sr(in Sb) electrochemical cell was used to measure emf values at 833–1113 K for Sr mole fractions over xSr = 0.03–0.84. The activity of Sr in liquid Sb was as low as 6.9 × 10−13 at 973 K and xSr = 0.03, implying strong chemical interactions. Six intermetallic compounds were confirmed by X-ray diffraction (XRD): SrSb2, Sr2Sb3, Sr11Sb10, Sr16Sb11, Sr5Sb3, and Sr2Sb. Phase transition temperatures were verified by differential scanning calorimetry (DSC) for xSr = 0.03–0.48. Integrating the thermodynamic properties of the Sr-Sb system from emf, XRD, and DSC measurements, three characteristic transition temperatures were newly defined and an experimentally-determined Sr-Sb phase diagram was constructed up to xSr = 0.50.