Synthesis, Crystal Structure, and Magnetic Properties of Pyrochlore‐Type Eu 2 Ta 2 (O,N) 7+ δ
| Autor: | Björn Anke, Christian Lorent, Theresa Block, Oliver Janka, Martin Lerch, Rainer Pöttgen, Sophie Hund |
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| Rok vydání: | 2017 |
| Předmět: |
Inorganic chemistry
Pyrochlore chemistry.chemical_element 02 engineering and technology Crystal structure engineering.material 010402 general chemistry 021001 nanoscience & nanotechnology 01 natural sciences Magnetic susceptibility 0104 chemical sciences law.invention Inorganic Chemistry Paramagnetism Crystallography chemistry law X-ray crystallography engineering 0210 nano-technology Europium Electron paramagnetic resonance Powder diffraction |
| Zdroj: | Zeitschrift für anorganische und allgemeine Chemie. 643:1824-1830 |
| ISSN: | 1521-3749 0044-2313 |
| Popis: | Pyrochlore-type Eu2Ta2(O,N)7+δ phases were prepared by reaction of ammonia with an amorphous europium tantalum oxide precursor. 151Eu Mossbauer and EPR spectroscopy as well as magnetic susceptibility measurements point to the presence of exclusively Eu3+. For phase-pure samples (X-ray powder diffraction), the nitrogen content varies between 1.0 and 1.8 wt %, leading to compositions in the range Eu2Ta2O7.1N0.6 – Eu2Ta2O6.5N1.0. Pyrochlore-type phases are structurally derived from the fluorite type with 1/8 of the anions missing, resulting in an ideal composition A2B2X7. In Eu2Ta2(O,N)7+δ the excess anions partly occupy these vacancies. The prepared phases are colorless with a direct optical bandgap of 4.3 eV and they show the typical Van Vleck paramagnetic behavior known for trivalent Eu atoms. |
| Databáze: | OpenAIRE |
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