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Electrical Conductivities of (CeO 2 ) 1− x (Y 2 O 3 ) x Thin Films
Author(s) -
Tian Chunyan,
Chan SiuWai
Publication year - 2002
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.1151-2916.2002.tb00439.x
Subject(s) - grain boundary , materials science , space charge , thin film , dielectric spectroscopy , impurity , electrical resistivity and conductivity , condensed matter physics , analytical chemistry (journal) , dopant , strontium titanate , misorientation , mineralogy , microstructure , composite material , electron , chemistry , doping , nanotechnology , engineering , chromatography , quantum mechanics , electrochemistry , physics , optoelectronics , organic chemistry , electrode , electrical engineering
Electrical properties of CeO 2 thin films of different Y 2 O 3 dopant concentration as prepared earlier were studied using impedance spectroscopy. The ionic conductivities of the films were found to be dominated by grain boundaries of high conductivity as compared with that of the bulk ceramic of the same dopant concentration sintered at 1500°C. The film grain‐boundary conductivities were investigated with regard to grain size, grain‐boundary impurity segregation, space charge at grain boundaries, and grain‐boundary microstructures. Because of the large grain boundary and surface area in thin films, the impurity concentration is insufficient to form a continuous highly resistive Si‐rich glassy phase at grain boundaries, such that the resistivity associated with space‐charge layers becomes important. The grain‐boundary resistance may originate from oxygen‐vacancy‐trapping near grain boundaries from space‐charge layers. High‐resolution transmission electron microscopy coupled with a trans‐boundary profile of electron energy loss spectroscopy gives strong credence to the space‐charged layers. Since the conductivities of the films were observed to be independent of crystallographic texture, the interface misorientation contribution to the grain‐boundary resistance is considered to be negligible with respect to those of the impurity layer and space‐charge layers.