Autor:	A. R. Dinesen, C. T. Pedersen, C. Bender Koch
Rok vydání:	2001
Předmět:	Chemistry Maghemite Infrared spectroscopy Hematite engineering.material Nanocrystal Chemical engineering visual_art Phase (matter) Mössbauer spectroscopy X-ray crystallography visual_art.visual_art_medium engineering Lepidocrocite Nuclear chemistry
Zdroj:	Journal of Thermal Analysis and Calorimetry. 64:1303-1310
ISSN:	1418-2874
DOI:	10.1023/a:1011582004634
Popis:	The thermal conversion of lepidocrocite (γ-FeOOH) into maghemite (γ-Fe2O3)and hematite (α-Fe2O3) has been studied by dynamic (DSC) and static heating experiments. Dynamic heating defines two main regions: conversion of lepidocrocite to maghemite (endothermal signal peaking at 255°C) and conversion of maghemite to hematite (exothermal signal peaking at 450°C). In addition, an exotherm following the lepidocrocite to maghemite endotherm is observed. The maghemite phase appears as porous aggregates of nanocrystals characterized by an extensive spin-canting. We suggest that the additional exotherm is associated with structural changes and a decreasing extent of spin-canting in the maghemite phase.
Databáze:	OpenAIRE
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