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Synthesis and Ionic Conductivity of Nanophase Ca1-xLaxF2+x

Published online by Cambridge University Press:  25 February 2011

Xijun Wu
Affiliation:
Institute of Solid State Physics, Academia Sinica, 230031 Hefei, China
Fang Su
Affiliation:
Centre of Fundamental Physics, University of Science and Technology of China, 230026 Hefei, China
Xiaoying Qin
Affiliation:
Institute of Solid State Physics, Academia Sinica, 230031 Hefei, China
Bin Xie
Affiliation:
Centre of Fundamental Physics, University of Science and Technology of China, 230026 Hefei, China
Xiaoli Ji
Affiliation:
Institute of Solid State Physics, Academia Sinica, 230031 Hefei, China
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Abstract

The nanophase ionic conductors Ca1-xLaxF2+x with x=0 and 0.25 were synthesized by an inert gas condensation and in situ compacting technique. The samples with average grain size of 16 na for nanophase CaF2 and 11 nm for nanophase Ca0.75 La0.25F2.25 were prepared under the compacting pressure of 0.5 GPa. The alternating ionic conductivity was deduced from the temperature dependence of the complex impedance.

The results indicated that the logarithm of ionic conductivity obeys Arrhenius relation in the temperature range from 300 °C to 530 °C both for nanophase CaF2 and for nanophase Ca0.75La0.25F2.25. Their activation energies are 1.14 eV and 1.00 eV, respectively. The ionic conductivity of nanophase CaF2 is about one and two orders of magnitude higher than that of polycrystalline and single crystal CaF2, respectively. While the ionic conductivity of nanophase Ca0.75La0.25F2.25 is about one order of magnitude higher than that of nanophase CaF2. Further analysis indicated that the enhanced ionic conductivity of nanophase Ca1-xLaxF2+x is related to the large volume fraction of interfaces.

Type
Research Article
Copyright
Copyright © Materials Research Society 1993

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References

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