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Formation of Potential Barrier Related to Grain‐Boundary Character in Semiconducting Barium Titanate
Author(s) -
Hayashi Katsuro,
Yamamoto Takahisa,
Ikuhara Yuichi,
Sakuma Taketo
Publication year - 2000
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.1151-2916.2000.tb01616.x
Subject(s) - grain boundary , materials science , barium titanate , condensed matter physics , rectangular potential barrier , effective diffusion coefficient , grain boundary strengthening , grain boundary diffusion coefficient , annealing (glass) , thermal diffusivity , sintering , crystallite , electrical resistivity and conductivity , temperature coefficient , mineralogy , metallurgy , ceramic , composite material , thermodynamics , microstructure , chemistry , physics , medicine , optoelectronics , quantum mechanics , magnetic resonance imaging , radiology
Resistance–temperature ( R – T ) characteristics were measured directly at single‐grain boundaries in 0.1‐mol%‐niobium‐doped barium titanate bicrystals that had been fabricated from polycrystalline sinters, to determine a geometrical grain‐boundary character dependence of the positive temperature coefficient of resistivity (PTCR) effect. Both random boundaries and low‐Σ boundaries exhibit a similar grain‐boundary character dependence of the PTCR effect through a simple geometrical analysis, using the coincidence of reciprocal lattice points. Differences of the R – T characteristics in individual boundaries have been explained in terms of the formation of a potential barrier that is associated with the oxidation of grain boundaries during cooling, after sintering or annealing. The grain‐boundary character is likely to affect the diffusivity of O 2− ions and, hence, is crucial to the formation of the potential barrier.