Structural studies of CaAl12O19, SrAl12O19, La2/3+δ Al12–δO19, and CaAl10NiTiO19 with the hibonite structure; indications of an unusual type of ferroelectricity
| Autor: | Arthur W. Sleight, Elena A. Medina, Judith K. Stalick, Munirpallam A. Subramanian, Jun Li |
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| Rok vydání: | 2016 |
| Předmět: |
Chemistry
Neutron diffraction Structure (category theory) 02 engineering and technology General Chemistry Crystal structure engineering.material Type (model theory) 021001 nanoscience & nanotechnology 01 natural sciences Ferroelectricity Crystallography 0103 physical sciences engineering Hibonite 010306 general physics 0210 nano-technology |
| Zdroj: | Zeitschrift für Naturforschung B. 71:475-484 |
| ISSN: | 1865-7117 0932-0776 |
| DOI: | 10.1515/znb-2015-0224 |
| Popis: | Various oxides with the hibonite structure were synthesized and structurally analyzed using powder neutron diffraction. The structure of CaAl12O19 at 298 and 11 K shows dipoles that are apparently too dilute to order unless subjected to a suitable electric field. Magnetoplumbites, such as BaFe12O19, are isostructural with hibonite. These compounds possess ferromagnetic properties, which combined with the electric dipoles may influence multiferroic behavior. Our SrAl12O19 sample showed two distinct hexagonal phases, a major phase with the normal hibonite structure and a minor phase having a closely related structure. Our sample of the defect hibonite phase La2/3+δAl12–δO19 shows a distinctly higher δ value (0.25) vs. that reported (~0.15) for samples made from the melt. Finally, we used to advantage the negative scattering length of Ti to determine the site occupancies of Ni and Ti in CaAl10NiTiO19. |
| Databáze: | OpenAIRE |
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