Infrared study of the thermal transformation of hematite and protohematite to magnetite in alkali iodide disks

S. Yariv*, E. Mendelovici

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

8 Scopus citations

Abstract

Disk of protohematite as well as of unground, mild and drastically ground hematite (0.5-2.5 mg) in KI or CsI (400 mg) were gradually heated to 500°C, and the thermal behaviour was investigated by infrared spectroscopy and magnetic attractibility. At 500°C a transitional oxide is obtained which is characterized by magnetic attractability. Only trace amounts of hematite are converted to the transitional oxide. However, if the hematite had been drastically ground before the preparation of the disks it was almost completely transformed into the transitional oxide. The transitional oxide from protohematite is converted on prolonged heating at 500°C to maghemite in CsI disks, but not in KI disks. At 600°C the transitional oxides obtained from protohematite or from the drastically pre-ground hematite as well as the maghemite are partly transformed into megnetite, whereas the rest of the iron oxide is recrystallized to hematite, whose spectrum shows the features of an unground material. The recrystallization process occurs more effectively in the CsI disks than in the KI disks, Crystal growth also identified with the disks of non-ground hematite, where magnetite is not detected.

Original languageEnglish
Pages (from-to)37-61
Number of pages25
JournalMaterials Chemistry
Volume5
Issue number1
DOIs
StatePublished - 1980
Externally publishedYes

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