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Magnetic and structural properties of magnetite in radular teeth of chiton Acanthochiton rubrolinestus
Author(s) -
Han Yunan,
Liu Chuanlin,
Zhou Dong,
Li Fashen,
Wang Yong,
Han Xiufeng
Publication year - 2011
Publication title -
bioelectromagnetics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.435
H-Index - 81
eISSN - 1521-186X
pISSN - 0197-8462
DOI - 10.1002/bem.20636
Subject(s) - magnetite , crystallite , superparamagnetism , materials science , squid , magnetization , mineralogy , magnetometer , transmission electron microscopy , condensed matter physics , nuclear magnetic resonance , magnetic field , nanotechnology , chemistry , metallurgy , ecology , physics , quantum mechanics , biology
The teeth of the Polyplacophora Chiton Acanthochiton Rubrolinestus contain biomineralized magnetite crystallites whose biological functions in relation to structure and magnetic properties are not well understood. Here, using superconducting quantum interference device (SQUID) magnetometry, we find that the saturation magnetization ( σ s ) and the Verwey transition temperature ( T v ) of tooth particles are 78.4 emu/g and 105 K, respectively. These values are below those of the stoichiometric magnetite. An in situ examination of the structure of the magnetite‐bearing region within an individual tooth using high‐resolution transmission electron microscopy indicates magnetite microcrystals form electron‐dense polycrystalline sheets with typical lengths of about 800 nm and widths of about 150 nm. These polycrystalline sheets are arranged regularly along the longitudinal direction of the tooth cutting surface. In addition, the crystallites in polycrystalline sheets take on generally good crystallinity. The magnetic microstructures of in situ magnetic force microscopy demonstrate that the [111] easy direction of magnetite microcrystals are aligned along the length of the tooth, whereas the [1 ${\bar {1}}$ 1] direction is parallel to the thickness of the tooth. Both Mössbauer spectra and magnetization versus temperature measurements under field cooled and zero‐field cooled conditions do not detect superparamagnetic magnetite crystallites in the mature major lateral tooth particles of this chiton. Bioelectromagnetics 32:226–233, 2011. © 2010 Wiley‐Liss, Inc.