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Effect of Porosity on the Electrical Properties of Polycrystalline Sodium Niobate: I, Electrical Conductivity
Author(s) -
Lanfredi Silvania,
Dessemond Laurent,
Rodrigues Ana C. M.
Publication year - 2003
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1151-2916.2003.tb00014.x
Subject(s) - materials science , electrical resistivity and conductivity , porosity , arrhenius equation , activation energy , crystallite , ceramic , microstructure , conductivity , mineralogy , tetragonal crystal system , composite material , nyquist plot , dielectric spectroscopy , analytical chemistry (journal) , atmospheric temperature range , phase (matter) , chemistry , thermodynamics , electrode , metallurgy , organic chemistry , physics , chromatography , electrochemistry , electrical engineering , engineering
The electrical behavior of NaNbO 3 ceramic samples with different relative densities was investigated by ac impedance spectroscopy in a range of 13 MHz to 10 −3 Hz between 400° and 800°C in dry air. Measurements were performed during heating and cooling cycles. The Nyquist impedance diagrams of dense sodium niobate exhibit only one semicircle representing the grain contribution with depression angles as small as 1°, indicating a high homogeneity of the specific electrical properties. In the case of porous samples, the data reveal an additional low‐frequency semicircle related to microstructure. For all studied samples, the Arrhenius conductivity plots show a change in the activation energy around 640°C, attributed to the tetragonal‐cubic phase transition. The electrical conductivity of porous samples appears to be higher than that of dense ones.