A reaction mechanism of atmospheric sintering for copper-phosphorus alloy electrode

In this study, we propose a reaction mechanism for atmospherically sintered copper-phosphorus (CueP) alloy electrodes which are expected to replace silver (Ag) electrodes. Structural analysis using transmission electron microscopy (TEM) has revealed that not only copper phosphide (Cu3P) but also copper phosphates of Cu2P2O7, Cu-3(PO4)(2) and Cu2PO4 distributed mainly at the P-concentrated region of the metallic part, where Cu3P distributed before sintering. In addition, the ordered superstructures which have a period based on the specific lattice spacing of Cu3P {002} were newly discovered. From structural analysis, we estimated the mechanisms comprised of the decomposition of Cu3P accompanied by a lack of Cu and P, then formation of metastable phases involving structural vacancies, and eventual transition to the copper phosphates. We also discussed another manner of forming the copper phosphates by the thermo-dynamical approach. Our results may provide a way to reduce the electrical resistivity of Cu-P alloy electrodes by controlling the structures including the deoxidized Cu. (C) 2016 Elsevier B.V. All rights reserved.