Effective dielectric function of porous Pb(Mg.sub.1/3./sub.Nb.sub.2/3./sub.O.sub.3./sub. ceramics

0434319 - FZÚ 2015 RIV US eng J - Článek v odborném periodiku
Nuzhnyy, Dmitry - Petzelt, Jan - Rychetský, Ivan - Trefalt, G.
Effective dielectric function of porous Pb(Mg_1/3Nb_2/3O₃ ceramics.
Physical Review. B. Roč. 89, č. 21 (2014), "214307-1"-"214307-5". ISSN 1098-0121
Grant CEP: GA ČR GAP204/12/0232
Institucionální podpora: RVO:68378271
Klíčová slova: PMN ceramics * infrared and THz spectroscopy * effective medium models * finite element method
Kód oboru RIV: BM - Fyzika pevných látek a magnetismus
Impakt faktor: 3.736, rok: 2014

A set of Pb(Mg1/3Nb2/3)O3 (PMN) relaxor ceramics with different porosities (66–96% of theoretical density) was processed from the pure perovskite PMN powder by varying the sintering temperature (930–980 K) and isostatic pressure. We measured and fitted the room temperature infrared (IR) reflectivity of corresponding polished ceramics, from which the effective dielectric function was obtained. The results were compared with the low- frequency permittivity data and discussed using several effectivemedium models. The best results were obtained using the Lichtenecker model, which fits quite well the IR spectra as well as the static permittivity for all the porosity values. Also the simulation using the finite element method supported the same model. It allows us to conclude that the samples show quite complex shape and topology of the pores, but all of the pores show similarity with a weak nonzero percolation (open porosity).
Trvalý link: http://hdl.handle.net/11104/0238394