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Calcium Site Occupancy in BaTiO3

Published online by Cambridge University Press:  21 February 2011

H. M. Chan ,
M. P. Harmer ,
M. Lal  and
D. M. Smyth
H. M. Chan
Affiliation:
Materials Research Center, Lehigh University, Bethlehem, PA 18015, U.S.A.
M. P. Harmer
Affiliation:
Materials Research Center, Lehigh University, Bethlehem, PA 18015, U.S.A.
M. Lal
Affiliation:
Materials Research Center, Lehigh University, Bethlehem, PA 18015, U.S.A.
D. M. Smyth
Affiliation:
Materials Research Center, Lehigh University, Bethlehem, PA 18015, U.S.A.
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Abstract

Measurements of the equilibrium electrical conductivity of Ca-doped BaTiO3 indicate a highly acceptor-doped behavior when y > 1 in the general formula (Ba1−xCaxO)yTiO2. It has been suggested that when there is an excess of alkaline earth oxides, some Ca++ occupies Ti-sites, where it acts as a doubly charged acceptor, CaTi''. This possibility has been checked with a recently developed technique for determining the crystallographic site occupancy of impurity atoms. Known as ALCHEMI (Atom Location Using Channeling-Enhanced Microanalysis), the technique relies on the dependence of the characteristic X-ray emission on the incident electron beam direction. A significant channeling effect was observed for slightly positive and negative excitations of the [100] reflection. The results indicate that for the composition (Ba0, 85Ca0.15O)1.02TiO2.00, a substantial fraction of the total calcium (> 20%) occupies Ti sites.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 31: Symposium N – Electron Microscopy of Materials , 1983 , 345
Copyright
Copyright © Materials Research Society 2006

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References

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