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Grain Boundary Segregation and High Nonlinear I – V Characteristics in Fe‐Added Strontium Titanate
Author(s) -
Wang SeongMin,
Kang SukJoong L.
Publication year - 2008
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.1551-2916.2008.02532.x
Subject(s) - grain boundary , strontium titanate , materials science , annealing (glass) , dopant , analytical chemistry (journal) , metal , titanate , doping , grain boundary diffusion coefficient , mineralogy , condensed matter physics , metallurgy , ceramic , nanotechnology , microstructure , thin film , chemistry , physics , optoelectronics , chromatography
The nonlinear current–voltage ( I – V ) characteristics of SrTiO 3 have been improved greatly by inducing nonequilibrium segregation of Fe‐acceptor dopant at grain boundaries. When Fe‐doped SrTiO 3 samples with different Fe additions (0, 0.2, 0.5, 1, 2, and 3 mol%) were sintered at 1350°C in H 2 , metallic Fe particles were precipitated at grain boundaries and triple junctions. During subsequent air‐annealing at 1100°C, the metallic Fe in the H 2 ‐sintered samples oxidized as Fe 2 O 3 and FeO, and the Fe ions diffused along and segregated at the grain boundaries in the surface region of the sample. The annealed samples showed excellent nonlinear I – V characteristics (α≈173), suggesting that an electrical potential barrier was formed at grain boundaries by the air‐annealing. As the amount of Fe increased up to 2 mol%, the nonlinear properties considerably increased as long as the Fe ion diffusion into the bulk grains was not considerable. The present investigation shows the processing and applicability of Fe‐doped SrTiO 3 as a new nonlinear device material.