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High Temperature Stable Maghemite Nanoparticles Sandwiched between Hectorite Nanosheets
Author(s) -
Ament Kevin,
Wagner Daniel R.,
Meij Frederieke E.,
Wagner Friedrich E.,
Breu Josef
Publication year - 2020
Publication title -
zeitschrift für anorganische und allgemeine chemie
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.354
H-Index - 66
eISSN - 1521-3749
pISSN - 0044-2313
DOI - 10.1002/zaac.202000077
Subject(s) - maghemite , hectorite , materials science , hematite , chemical engineering , nanoparticle , physisorption , phase (matter) , ostwald ripening , montmorillonite , nanotechnology , chemistry , adsorption , organic chemistry , composite material , metallurgy , engineering
Maghemite (γ‐Fe 2 O 3 ) is a metastable iron oxide phase and usually undergoes fast phase transition to hematite at elevated temperatures (>350 °C). Maghemite nanoparticles were synthesized by the polyol method and then intercalated into a highly swollen (>100 nm separation) nematic phase of hectorite. A composite of maghemite nanoparticles sandwiched between nanosheets of synthetic hectorite was obtained. The confinement of the nanoparticles hampered Ostwald ripening up to 700 °C and consequently the phase transition to hematite is suppressed. Only above 700 °C γ‐Fe 2 O 3 nanoparticles started to grow and undergo phase transition to α‐F 2 O 3 . The structure and the phase transition of the composite was evaluated using X‐ray diffraction, TEM, SEM, physisorption, TGA/DSC, and Mößbauer spectroscopy.