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Core‐Shell Structure Formation in Nb 2 O 5 ‐Doped SrTiO 3 by Oxygen Partial Pressure Change
Author(s) -
Chung SungYoon,
Lee ByoungKi,
Kang SukJoong L.
Publication year - 1998
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.1151-2916.1998.tb02730.x
Subject(s) - oxidizing agent , sintering , materials science , reducing atmosphere , doping , oxygen , atmosphere (unit) , shell (structure) , partial pressure , analytical chemistry (journal) , strontium titanate , strontium , mineralogy , core (optical fiber) , crystallography , nanotechnology , chemistry , metallurgy , composite material , thin film , thermodynamics , physics , optoelectronics , organic chemistry , chromatography
A core‐shell structure was observed in SrTiO 3 doped with 1.2 mol% of Nb 2 O 5 , after sintering in a reducing atmosphere (5H 2 ‐95N 2 ) and then in an oxidizing atmosphere (air). In undoped and Al 2 O 3 ‐doped SrTiO 3 specimens, no core‐shell structure formed after the same sintering treatments as those for SrTiO 3 doped with 1.2 mol% of Nb 2 O 5 . The measured chemical compositions of the core and shell regions of 1.2‐mol%‐Nb 2 O 5 ‐doped SrTiO 3 grains showed that the Sr/(Ti + Nb) ratio of the shell regions grown in air was ~1% less than that of core regions grown in 5H 2 ‐95N 2 , which was in good agreement with a value predicted by available defect equations. Therefore, the observed core‐shell structure is thought to result from the formation of strontium vacancies in an oxidizing atmosphere.