Identification of the impurity phase in high-purity CeB6 by convergent-beam electron diffraction
| Autor: | Ding Peng, Philip N. H. Nakashima |
|---|---|
| Rok vydání: | 2019 |
| Předmět: |
0303 health sciences
Materials science Space group 02 engineering and technology 021001 nanoscience & nanotechnology Condensed Matter Physics Biochemistry Molecular physics Inorganic Chemistry Crystal 03 medical and health sciences chemistry.chemical_compound Tetragonal crystal system Electron diffraction chemistry Structural Biology Impurity Scanning transmission electron microscopy General Materials Science Density functional theory Physical and Theoretical Chemistry Cerium hexaboride 0210 nano-technology 030304 developmental biology |
| Zdroj: | Acta Crystallographica Section A Foundations and Advances. 75:489-500 |
| ISSN: | 2053-2733 |
| DOI: | 10.1107/s2053273319000354 |
| Popis: | The rare earth hexaborides are known for their tendency towards very high crystal perfection. They can be grown into large single crystals of very high purity by inert gas arc floating zone refinement. The authors have found that single-crystal cerium hexaboride grown in this manner contains a significant number of inclusions of an impurity phase that interrupts the otherwise single crystallinity of this prominent cathode material. An iterative approach is used to unequivocally determine the space group and the lattice parameters of the impurity phase based on geometries of convergent-beam electron diffraction (CBED) patterns and the symmetry elements that they possess in their intensity distributions. It is found that the impurity phase has a tetragonal unit cell with space group P4/mbm and lattice parameters a = b = 7.23 ± 0.03 and c = 4.09 ± 0.02 Å. These agree very well with those of a known material, CeB4. Confirmation that this is indeed the identity of the impurity phase is provided by quantitative CBED (QCBED) where the very close match between experimental and calculated CBED patterns has confirmed the atomic structure. Further confirmation is provided by a density functional theory calculation and also by high-angle annular dark-field scanning transmission electron microscopy. |
| Databáze: | OpenAIRE |
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