Origin and stability of the dipolar response in a family of tetragonal tungsten bronze relaxors
| Autor: | Finlay D. Morrison, Aziz Daoud-Aladine, Donna C. Arnold, Andrei Rotaru |
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| Jazyk: | angličtina |
| Rok vydání: | 2011 |
| Předmět: |
Diffraction
Condensed Matter - Materials Science Materials science Neutron diffraction Materials Science (cond-mat.mtrl-sci) FOS: Physical sciences chemistry.chemical_element Crystal structure Dielectric Neutron scattering Tungsten Condensed Matter Physics Electronic Optical and Magnetic Materials Condensed Matter::Materials Science Tetragonal crystal system Dipole Crystallography Nuclear magnetic resonance chemistry |
| Popis: | A new family of relaxor dielectrics with the tetragonal tungsten bronze structure (nominal composition Ba6M3+Nb9O30, M3+ = Ga, Sc or In) were studied using dielectric spectroscopy to probe the dynamic dipole response and correlate this with the crystal structure as determined from powder neutron diffraction. Independent analyses of real and imaginary parts of the complex dielectric function were used to determine characteristic temperature parameters, TVF, and TUDR, respectively. In each composition both these temperatures correlated with the temperature of maximum crystallographic strain, Tc/a determined from diffraction data. The overall behaviour is consistent with dipole freezing and the data indicate that the dipole stability increases with increasing M3+ cation size as a result of increased tetragonality of the unit cell. Crystallographic data suggests that these materials are uniaxial relaxors with the dipole moment predominantly restricted to the B1 cation site in the structure. Possible origins of the relaxor behaviour are discussed. Main article 32 pages, 8 figures; Supplementary data 24 pages, 4 figures |
| Databáze: | OpenAIRE |
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