This study deals with some microstructural and crystallographic aspects of the thermally induced trans- formation of goethite (a-FeOOH) into hematite (a-Fe2O3), occurring at about 300 °C. Powder specimens of goethite have been annealed in air at different temperatures, ranging from 200 °C up to 1,000 °C. The resulting products have been analyzed for a complete characterization of the changes brought about by the thermal treatments, using a multianalytical approach, based on: thermogravimetry, differential thermal analysis, transmission electron microscopy, Raman spectroscopy, and X-ray diffraction. At lower temperatures, the transition to hematite produces no important changes in size and shape of the original goethite grains. Recrystallization, and partial sintering, occurs only at temperatures in excess of 800 °C. The rel- evant evolution of pores present in both phases has been also considered, as it may provide important indications on the actual formation mechanism of hematite.

On the geothite to hematite phase transformation

Gialanella, Stefano;Girardi, Fabrizio;Ischia, Gloria;Lonardelli, Ivan;Mattarelli, Maurizio;Montagna, Maurizio
2010-01-01

Abstract

This study deals with some microstructural and crystallographic aspects of the thermally induced trans- formation of goethite (a-FeOOH) into hematite (a-Fe2O3), occurring at about 300 °C. Powder specimens of goethite have been annealed in air at different temperatures, ranging from 200 °C up to 1,000 °C. The resulting products have been analyzed for a complete characterization of the changes brought about by the thermal treatments, using a multianalytical approach, based on: thermogravimetry, differential thermal analysis, transmission electron microscopy, Raman spectroscopy, and X-ray diffraction. At lower temperatures, the transition to hematite produces no important changes in size and shape of the original goethite grains. Recrystallization, and partial sintering, occurs only at temperatures in excess of 800 °C. The rel- evant evolution of pores present in both phases has been also considered, as it may provide important indications on the actual formation mechanism of hematite.
2010
3
Gialanella, Stefano; Girardi, Fabrizio; Ischia, Gloria; Lonardelli, Ivan; Mattarelli, Maurizio; Montagna, Maurizio
File in questo prodotto:
File Dimensione Formato  
2010_On_the_goethite_JTAC_102_867_873.pdf

Solo gestori archivio

Tipologia: Versione editoriale (Publisher’s layout)
Licenza: Tutti i diritti riservati (All rights reserved)
Dimensione 501.5 kB
Formato Adobe PDF
501.5 kB Adobe PDF   Visualizza/Apri

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11572/83982
Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus 145
  • ???jsp.display-item.citation.isi??? 139
social impact