TY - JOUR
T1 - Structural transformations of heat-treated bacterial iron oxide
AU - Hashimoto, Hideki
AU - Fujii, Tatsuo
AU - Kohara, Shinji
AU - Nakanishi, Koji
AU - Yogi, Chihiro
AU - Peterlik, Herwig
AU - Nakanishi, Makoto
AU - Takada, Jun
N1 - Funding Information:
This study was financially supported by the Special Funds for Education and Research from the Ministry of Education, Culture, Sports, Science and Technology and JSPS KAKENHI Grant Number 24654089 , 24510151 , 24760550 , and 23360309 . Soft X-ray XAFS measurements were performed at BL-10 in SR center. HEXRD experiments were performed at BL04B2 in SPring-8 with the approval of the Japan Synchrotron Radiation Research Institute (JASRI) (Proposal No. 2007A1883, 2009B1116, and 2013A1098). Fe K-edge XAFS measurements were performed with approval from the Photon Factory Program Advisory Committee (Proposal No. 2007G112).
Publisher Copyright:
© 2015 Elsevier B.V. All rights reserved.
PY - 2015/4/1
Y1 - 2015/4/1
N2 - A bacterial siliceous iron oxide microtubule (diameter: ca. 1 μm, 15Fe2O3·8SiO2·P2O5·30H2O) produced by Leptothrix ochracea was heat treated in air and its structural transformation was investigated in detail by microscopy, diffractometry, and spectroscopy. Although the heat-treated bacterial iron oxide retained its original microtubular structure, its nanoscopic, middle-range, and local structures changed drastically. Upon heat treatment, nanosized pores were formed and their size changed depending on temperature. The Fe-O-Si linkages were gradually cleaved with increasing temperature, causing the progressive separation of Fe and Si ions into iron oxide and amorphous silicate phases, respectively. Concomitantly, global connectivity and local structure of FeO6 octahedra in the iron oxide nanoparticles systematically changed depending on temperature. These comprehensive investigations clearly revealed various structural changes of the bacterial iron oxide which is an important guideline for the future exploration of novel bio-inspired materials.
AB - A bacterial siliceous iron oxide microtubule (diameter: ca. 1 μm, 15Fe2O3·8SiO2·P2O5·30H2O) produced by Leptothrix ochracea was heat treated in air and its structural transformation was investigated in detail by microscopy, diffractometry, and spectroscopy. Although the heat-treated bacterial iron oxide retained its original microtubular structure, its nanoscopic, middle-range, and local structures changed drastically. Upon heat treatment, nanosized pores were formed and their size changed depending on temperature. The Fe-O-Si linkages were gradually cleaved with increasing temperature, causing the progressive separation of Fe and Si ions into iron oxide and amorphous silicate phases, respectively. Concomitantly, global connectivity and local structure of FeO6 octahedra in the iron oxide nanoparticles systematically changed depending on temperature. These comprehensive investigations clearly revealed various structural changes of the bacterial iron oxide which is an important guideline for the future exploration of novel bio-inspired materials.
KW - Amorphous materials
KW - Composite materials
KW - Nanostructures
KW - Oxides
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U2 - 10.1016/j.matchemphys.2015.01.067
DO - 10.1016/j.matchemphys.2015.01.067
M3 - Article
AN - SCOPUS:84924545190
SN - 0254-0584
VL - 155
SP - 67
EP - 75
JO - Materials Chemistry and Physics
JF - Materials Chemistry and Physics
ER -