Polymorphism in Micro-, Submicro-, and Nanocrystalline NaNbO3
| Autor: | Jiirgen Dornseiffer, Christian Pithan, Arnaud Magrez, Franz-Hubert Haegel, Rainer Waser, Yosuke Shiratori |
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| Rok vydání: | 2005 |
| Předmět: |
Materials science
Chemistry Analytical chemistry General Medicine Crystal structure Nanocrystalline material Surfaces Coatings and Films Crystallography symbols.namesake Polymorphism (materials science) Materials Chemistry symbols Orthorhombic crystal system Particle size Physical and Theoretical Chemistry Raman spectroscopy Stoichiometry Powder diffraction |
| Zdroj: | The Journal of Physical Chemistry B. 109:20122-20130 |
| ISSN: | 1520-5207 1520-6106 |
| DOI: | 10.1021/jp052974p |
| Popis: | NaNbO(3) powders with various particle sizes (ranging from 30 nm to several microns) and well-controlled stoichiometry were obtained through microemulsion-mediated synthesis. The effect of particle size on the phase transformation of the prepared NaNbO(3) powders was studied using X-ray powder diffraction, Raman spectroscopy, and nuclear site group analysis based on these spectroscopic data. Coarsened particles exhibit an orthorhombic Pbcm (D(2h)(11), no. 57) structure corresponding to the bulk structure, as observed for single crystals or powders prepared by conventional solid-state reaction. The crystal symmetry of submicron powders was refined with the space group Pmc2(1) (C(2v)(2), no. 26). The reduced perovskite cell volumes of these submicron powders were most expanded compared to all the other structures. Fine particles with a diameter of less than 70 nm as measured from SEM observations showed an orthorhombic Pmma (D(2h)(5), no. 51) crystal symmetry. The perovskite formula cell of this structure was pseudocubic and was the most compact one. A possible mechanism of the phase transformation is suggested. |
| Databáze: | OpenAIRE |
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