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Functional Properties of CrFeCoNiCu and GeFeCoNiCu oxides

Functional Properties of CrFeCoNiCu and GeFeCoNiCu oxides

Category
Conference lecture and academic presentation
Abstract
The present work explores the concept of high-entropy alloys to design FeCoNi-based oxides suitable for functional applications. Fundamental changes in electronic behavior produced by metal substitution and variable oxygen content were screened to investigate the potential of these materials for specific applications, such as transparent conductors and thermoelectric materials. Elements with atomic radius similar to the average value expected for FeCoNi have been selected for substitutional replacement: (i) Cr and Cu as relatively abundant commodities with intensive industrial application and (ii) Ge due its semiconductor nature. CrFeCoNiCu and GeFeCoNiCu thin films with variable oxygen concentration were deposited by reactive DC magnetron sputtering onto optically transparent substrates and characterized by structural, spectroscopic and electrical methods. Transmission electron microscopy showed that for low oxygen content the materials adopted an fcc-type structure while the NaCl-structure was found for higher oxygen concentrations. X-ray-photoelectron spectroscopy was used to characterize the oxidation state of the metals. The resistivity measured at room temperature ranged from 10-4 to values above 104 Ω.cm. Hall measurements and Seebeck measurements show that both electrons and holes contribute to conduction and that at room temperature the Hall coefficient and Seebeck coefficient have different sign. This behaviour is discussed in terms of the structural analysis and suggested electronic model of the films.
Client
  • Norges forskningsråd / 275752
Language
English
Author(s)
Affiliation
  • SINTEF Industry / Sustainable Energy Technology
  • Norwegian University of Science and Technology
  • University of Oslo
  • University of Oslo
Presented at
Future Materials 2020
Date
25.02.2020 - 27.02.2020
Year
2020