PTC effect in doped BaTiO₃ceramics: evidence for a bulk contribution

Abstract

Using photolithographic techniques, four-probe electrical resistivity measurements of Nb-doped BaTiO3 ceramics, at the microscopic scale, are presented from room temperature up to 180 degrees C. The PTC effect displayed by several grains exhibits an abrupt jump at the Curie temperature, followed by a monotonic quasi linear increase of the resistance. This behaviour looks quite different from the usual PTC effect observed on macroscopic ceramics. The jump is clearly due to a change of resistance within the bulk. It appears, from the microscopical results, that the bulk itself must be partially involved in the increase of resistance above Tc contrary to the generally accepted theory.

Unveiling Alternating Current Electronic Properties at Ferroelectric Domain Walls

“…in polycrystalline ceramics. [120,[154][155][156][157][158][159][160][161][162][163] Furthermore, it found broad application in electrochemistry, [164,165] biochemistry, [166] and semiconductor technology. [167][168][169] A comprehensive review of experimental studies is provided in ref.…”

“…This technique was used, for example, to analyze the frequency‐dependent transport within grains, at grain boundaries, and dislocations in polycrystalline ceramics. [ 120,154–163 ] Furthermore, it found broad application in electrochemistry, [ 164,165 ] biochemistry, [ 166 ] and semiconductor technology. [ 167–169 ] A comprehensive review of experimental studies is provided in ref.…”

Donor and Acceptor Levels in Undoped β-FeSi2 Films Grown on Si (001) Substrates

“…However, Gillot and Michenaud reported a PTC effect from the bulk contribution, 14) and observed abrupt jumps of resistivity at each phase transition in heavily doped single crystals. 15) In polycrystalline PTCR materials, a continuous increase in resistivity above T C can be explained by the Heywang model, but an abrupt increase at T C is ascribed to the phase transi-ture range.…”