Thermodynamic studies of the Pt-Cu-P and Pt-Ni-P systems as a basis for systematic alloy development.

• Applicants: Dr. Ulrich Klotz; Professor Dr. Hans Jürgen Seifert
• Subject Area: Thermodynamics and Kinetics as well as Properties of Phases and Microstructure of Materials
• Term: since 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 536646051

Platinum phosphides, to which Ni and/or Cu are alloyed, have been the subject of much research for the development of electrocatalysts for almost 20 years. They show promising electrochemical behavior both in the crystalline, thermodynamically stable state and in the amorphous, metastable state. However, due to the lack of a fundamental thermodynamic description of the Pt-Cu-P and Pt-Ni-P ternary systems, on which the Pt-Cu-Ni-P quaternary system is founded, the fundamental knowledge necessary for systematic alloy development is lacking. Moreover, experimental work with phosphorus (P) is not harmless due to its toxic modification (white P), and in addition, its low sublimation temperature (about 300°C) greatly complicates experimental work. These conditions make previous high-throughput approaches to the study of metal phosphides impossible. The present research project aims to describe thermodynamically the ternary systems Pt-Cu-P and Pt-Ni-P and to model the melting equilibria of the quaternary system Pt-Cu-Ni-P in order to enable systematic alloy development for application-specific requirements. In addition to the description of the thermodynamic equilibria, the low-melting compositions required for glass formation can be identified in a more targeted manner than by classical systematic test series. To achieve the goal, the research project envisions efficiently unlocking the aforementioned systems through a clever combination of high-throughput experiments, established computer-aided methods, and subsequent targeted key experiments. The experimental work includes sample preparation by temperature gradient method, and the samples are investigated by thermal analysis (DTA, DSC, Flash DSC). In addition, microstructure investigations (SEM/EDX/WDX) and structural investigations (XRD) are performed with the aim of determining the chemical compositions and crystal structures of the respective phases.

• DFG Programme: Research Grants