Corrosion‐Free EMF Measurements of Zinc‐Based Intermetallic Compounds at Ambient Temperature. Issue 10 (7th April 2020)

• Record Type: Journal Article
• Authors: Kriegel, René; Armbrüster, Marc
• Is Part Of: Chemphyschem. Volume 21:Issue 10(2020)
• Page Start: 977
• Page End: 986
• Publication Date: 2020-04-07
• Subjects: determination of activity values, electromotive force, intermetallic compounds, potential measurement, thermodynamic data; Chemistry, Physical and theoretical -- Periodicals; 541.05
• DOI: 10.1002/cphc.201901218
• Languages: English
• ISSNs: 1439-4235

Abstract

Abstract: Material development requires in many cases information about the necessary stability of the materials against oxidation, which is encoded in the chemical activity of the constituting elements. Determination of the chemical activity is tedious, especially for metallic materials at or close to ambient temperature. To determine the chemical activity of Zn at ambient temperature, electromotive force (EMF) measurements on the intermetallic compounds ZnPd, ZnPt and Cu5 Zn8 within their respective homogeneity range were conducted. The single‐phase nature of the samples was confirmed by powder X‐ray diffraction, light microscopy as well as SEM/EDX analysis. To exclude oxidation, and therefore faulty determination of the electrochemical potentials, a method was developed to conduct the electrochemical measurements under non‐corrosive conditions in inert atmosphere. Corrosion by the electrolyte was avoided using anhydrous dimethylformamide as aprotic solvent. From the EMF the respective intrinsic activities of zinc in the corresponding intermetallic compounds was determined. Measurements on Cu5 Zn8 and comparison to available data in literature verified the developed method allowing to retrieve thermodynamic data of ZnPd and ZnPt for the first time at ambient temperature. The herein developed and easy‐to‐use methodology is applicable to a wide range of metallic material by choosing appropriate compositions of the electrolyte and has the potential to boost material development. Abstract : Activity from EMF : The chemical activity of elements in intermetallic compounds can be determined at room temperature by corrosion‐free measurements of the electromotive force. The methodology is based on DMF as water‐free solvent and use of inert atmosphere to prevent oxidation. Results on Zn‐containing intermetallic compounds have been verified by comparison to literature data. Overcoming corrosion issues makes the approach applicable to a wide range of materials.