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4259112 
Journal Article 
Magnetic and phonon transitions in B-site Co doped BiFeO3 ceramics 
Chiang, YS; Tu, ChiS; Chen, PinYi; Chen, CSao; Anthoniappen, J; Ting, Yi; Chan, TS; Schmidt, VH 
2016 
1 
Ceramics International
ISSN: 0272-8842
EISSN: 1873-3956 
42 
11 
13104-13112 
WOS:000378952100076 
Magnetic susceptibility and phonons have been characterized in multiferroic Bi(Fe1-xCox)O3-delta, ceramics for x=0.0, 0.05, and 0.10 (BFO100xCo) as functions of temperature. A preferred (100) crystallographic orientation and increasing average oxygen vacancies were observed in BFO5Co and BFO10Co. The Fe and Co K-edge synchrotron X-ray absorptions revealed mixed valences of Fe3+, Fe4+, Co2+, and Co3+ ions in BFO5Co and BFO10Co, which exhibit a ferromagnetic (or ferrimagnetic) phase below room temperature due to appearance of ferromagnetic B-O-B (B=Fe and Co) superexchange interactions. Field-cooled (FC) and zero-field-cooled (ZFC) magnetic susceptibilities exhibit a significant spin-glass splitting below room temperature in BFO5Co and BFO10Co. Two Raman-active phonon anomalies at similar to 170 K (or 200 K) and similar to 260 K were attributed to the Fe3+-O-Co3+ and Co3+-O-Co3+ magnetic orderings, respectively. This work suggests that the low-spin Co2+-O-Co2+, Fe3+-O-Fe3+ (or Fe4+), and high-spin Co2+-O-Co2+ superexchange interactions are responsible for phonon anomalies at similar to 290 (or similar to 300K), similar to 400, and similar to 470 K (or similar to 520 K) in BFO5Co and BFO10Co. (C) 2016 Elsevier Ltd and Techna Group S.r.l. All rights reserved. 
Bi(Fe1-xCox)O-3 ceramics; Magnetic susceptibility; Phonon; Transition; Superexchange