Broadband dielectric spectroscopy of phonons and polar nanoclusters in PbMg.sub.1/3./sub.Nb.sub.2/3./sub.O.sub.3./sub.-35%PbTiO.sub.3./sub. ceramics: Grain size effects

0340598 - FZÚ 2010 RIV US eng J - Článek v odborném periodiku
Bovtun, Viktor - Kamba, Stanislav - Veljko, Sergiy - Nuzhnyy, Dmitry - Kroupa, Jan - Savinov, Maxim - Vaněk, Přemysl - Petzelt, Jan - Holc, J. - Kosec, M. - Amorin, H. - Alguero, M.
Broadband dielectric spectroscopy of phonons and polar nanoclusters in PbMg_1/3Nb_2/3O₃-35%PbTiO₃ ceramics: Grain size effects.
Physical Review. B. Roč. 79, č. 10 (2009), 104111/1-104111/12. ISSN 1098-0121
Grant CEP: GA MŠMT OC 101; GA ČR(CZ) GA202/09/0682; GA ČR(CZ) GA202/06/0403; GA MŠMT OC09023
Výzkumný záměr: CEZ:AV0Z10100520
Klíčová slova: polar clusters * relaxor ferroelectrics * soft modes * phonons
Kód oboru RIV: BM - Fyzika pevných látek a magnetismus
Impakt faktor: 3.475, rok: 2009
http://link.aps.org/doi/10.1103/PhysRevB.79.104111

The dielectric response of PMN-35%PT ceramics from 100 Hz up to 100 THz was determined in a broad temperature range 5-900 K. Two ceramics were studied and compared: coarse grain ceramics (CGC - grain size ~ 4 µm) and fine grain ceramics (FGC – grain size ~ 150 nm). Both ceramics showed similar polar phonon response and the ferroelectric transition near TC = 440 K was manifested by partial softening of the overdamped lowest-frequency phonon. However, the dielectric response was dominated by a complex relaxational dispersion in the microwave range due to relaxor-like dynamics of the polar nanoclusters, which strongly differed in both the ceramics. Whereas the CGC undergoes a well-defined ferroelectric transition like a single crystal, FGC exhibits a relaxor behavior with substantially smaller permittivity showing partial clamping of the polar nanocluster dynamics by grain boundaries.
Trvalý link: http://hdl.handle.net/11104/0183808