Resistivity Anomaly in Semiconducting BaTiO3

Abstract
The phenomenon of positive temperature coefficient of resistivity (PTCR) anomaly has been reexamined in BaTiO3 with dopings Er and Tb, whose compositions can be expressed by the formulae: Ba1-xErxTiO3 and Ba1-xTbxTiO3. The effect of partial substitution of Ba2+ ion by Sr2+ and Ca2+ on the Curie point is also observed. The composition ranges examined were confined to the region of semiconductivity. Formation of single phase solid solution was checked by an X-ray analysis, using powder photograph method. A theoretical analysis of resistivity anomaly has been given by proposing a new mechanism based on the idea of scattering of an electron by spatial polarization fluctuations. It is found that PTCR anomaly is closely associated with the appearance and disappearance of dipole ordering in ferroelectric systems.

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