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

摘要

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) vertical bar CaF2-SrF2 vertical bar Sr(in Sb) electrochemical cell was used to measure emf values at 833-1113 K for Sr mole fractions over x(Sr) = 0.03 -0.84. The activity of Sr in liquid Sb was as low as 6.9 x 10(-13) at 973 K and x(Sr) = 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 x(Sr) = 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 x(Sr) = 0.50. (C) 2019 Elsevier Ltd. All rights reserved.