Structural and thermoelectric properties of Gd Sr2-CoO4 layered perovskites
| Autor: | J.L. Yan, J.X. Wei, Y. Yin |
|---|---|
| Rok vydání: | 2021 |
| Předmět: |
010302 applied physics
Materials science Valence (chemistry) Process Chemistry and Technology Analytical chemistry 02 engineering and technology 021001 nanoscience & nanotechnology 01 natural sciences Surfaces Coatings and Films Electronic Optical and Magnetic Materials Bond length Tetragonal crystal system Thermal conductivity X-ray photoelectron spectroscopy Electrical resistivity and conductivity Seebeck coefficient 0103 physical sciences Thermoelectric effect Materials Chemistry Ceramics and Composites 0210 nano-technology |
| Zdroj: | Ceramics International. 47:19835-19842 |
| ISSN: | 0272-8842 |
| DOI: | 10.1016/j.ceramint.2021.03.322 |
| Popis: | GdxSr2-xCoO4-layered perovskites with varying gadolinium content (x = 0.5, 0.6, 0.7, 0.8, 0.9, 1.0) were synthesised using a conventional solid-state reaction method in air. X-ray diffraction (XRD) analysis indicated that all samples were single phase with a tetragonal I4/mmm K2NiF4-type structure. Rietveld refinements showed that the lattice parameters and the in-plane Co–O bond length decreased with increasing Gd3+ content, suggesting stronger structural distortion. The X-ray photoelectron spectroscopy (XPS) analysis indicated that cobalt ions on the surface of GdxSr2-xCoO4 had Co3+ and Co4+mixed valence states and many oxygen vacancies. The thermoelectric properties of GdxSr2-xCoO4 (x = 0.7, 0.8) were also investigated. The temperature dependencies of the electrical conductivity (σ) and Seebeck coefficient (S) up to 750 °C for Gd0.7Sr1.3CoO4 showed maximum and minimum values at approximately 550 °C. Below 550 °C with increasing Gd3+ content, S increased, whereas σ and the thermal conductivity (κ) decreased, leading to an increase in the figure of merit (ZT). A maximum ZT value of 0.0039 for Gd0.8Sr1.2CoO4 was obtained at 400 °C. The variations of σ, S and κ with x and temperature are discussed. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|
Full Text from ScienceDirect