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Study of the Dielectric Properties of the Perovskite LaMn 0.5 Co 0.5 O 3–δ
Author(s) -
YáñezVilar S.,
CastroCouceiro A.,
RivasMurias B.,
Fondado A.,
Mira J.,
Rivas J.,
SeñarísRodríguez M. A.
Publication year - 2005
Publication title -
zeitschrift für anorganische und allgemeine chemie
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.354
H-Index - 66
eISSN - 1521-3749
pISSN - 0044-2313
DOI - 10.1002/zaac.200570055
Subject(s) - dielectric , crystallite , materials science , perovskite (structure) , particle size , analytical chemistry (journal) , mixed oxide , oxide , grain size , decomposition , oxygen , chemistry , crystallography , metallurgy , organic chemistry , optoelectronics
Abstract Polycrystalline samples of the charge ordered mixed oxide LaMn 0.5 Co 0.5 O 3−δ (T CO = 400 K) have been prepared by the nitrate decomposition method. These samples are biphasic, according to XRPD, and except one, oxygen defficient (δ ≈ 0.04‐0.05). The study of the dielectric properties of these samples reveal that LaMn 0.5 Co 0.5 O 3−δ displays a high dielectric constant, specially at room temperature and low frequencies. This ε′ r is seen to be strongly dependent on the particle size and not so much on the oxygen defficiency and the best properties are found in the sample with biggest particle size (ϕ = 7 μm) for which ε′ r (300 K) ≈ 10 5 up to 2x10 4 Hz. Analysis of the role of the grain size and the electrode contacts on the obtained data reveal that this mixed oxide has an intrinsic dielectric constant that is rather high for this type of compounds (ε′ r,∞ ≈ 30) and that is further enhanced by extrinsic Maxwell‐Wagner effects. We relate such enhanced intrinsic dielectric constant to the electronic process of charge ordering present in this material below 400 K.