Structure and properties of nano- and polycrystalline Mn-doped CuCr2Se4 obtained by ceramic method and high-energy ball milling
| Autor: | Jerzy Goraus, Jerzy Kubacki, Tomasz Goryczka, Josef Jampilek, K. Knizek, Ewa Pietrasik, Zoia Barsova, Izabela Jendrzejewska, Beata Witkowska-Kita |
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| Rok vydání: | 2021 |
| Předmět: |
Materials science
Mechanical Engineering Analytical chemistry 02 engineering and technology Crystal structure 010402 general chemistry 021001 nanoscience & nanotechnology Condensed Matter Physics 01 natural sciences Nanocrystalline material XANES 0104 chemical sciences Differential scanning calorimetry X-ray photoelectron spectroscopy Mechanics of Materials Curie temperature General Materials Science Crystallite 0210 nano-technology Superparamagnetism |
| Zdroj: | Materials Research Bulletin. 137:111174 |
| ISSN: | 0025-5408 |
| DOI: | 10.1016/j.materresbull.2020.111174 |
| Popis: | Chemical compounds with a general formula CuCr2–xMnxSe4 (x = 0.1, 0.2) were successfully synthesized in polycrystalline form, using solid state reaction method, and as nanoparticles, using high-energy ball milling. The influence of manganese and grain size on their structure, magnetic and thermal properties was investigated by X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), magnetic measurements (SQUID, high magnetic fields) and DSC (Differential Scanning Calorimetry). Electronic structures of obtained compounds were determined using XANES (X-ray Near Edge Absorption Spectroscopy) and XPS (X-ray Photoelectron Spectroscopy). X-ray studies confirmed that the spinel phase forms only for x = 0.1, 0.2. The obtained compounds crystallize with the space group F d 3 ¯ m . The results of magnetic measurements for poly- and nanocrystalline compounds showed that the polycrystalline compounds are ferromagnets with the Curie temperature of TC =352 K for x = 0.1 and TC =342 K for x = 0.2, and the Curie-Weiss temperature of θCW =362 K for x = 0.1 and θCW =354 K for x = 0.2. Whereas the nanoparticles CuCr2–xMnxSe4 (x = 0.1, 0.2) revealed a superparamagnetic character with blocking temperature of TB ≈ 25 K for both compounds. The XANES and XPS data indicate the Cr ions are trivalent (Cr3+). Mn ions are trivalent and tetravalent (Mn3+ and Mn4+), which implies small amount of the Cu ions change the valency from divalency to monovalency (Cu2+ and Cu1+). DSC/TG analysis indicates that the presence of Mn ions in the CuCr2Se4 crystal lattice affects the stability and resistance of the doped compounds in comparison with the pure CuCr2Se4. Decreasing the grain size leads to a decrease in melting temperature. |
| Databáze: | OpenAIRE |
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