An anomalous behaviour in the phase stability of the system Fe2O3and NiO

✍ Scribed by S. Rajendran; V. Sitakara Rao

• Publisher: Springer
• Year: 1994
• Tongue: English
• Weight: 600 KB
• Volume: 29
• Category: Article
• ISSN: 0022-2461
• DOI: 10.1007/bf00349963

✦ Synopsis

Iron-nickel mixed oxides containing up to 50 mol% of NiO were prepared by firing the corresponding co-precipitated hydrous oxides; characterization was performed by X-ray diffraction, infrared spectroscopy, magnetic susceptibility, electrical conductivity and thermoelectric power measurements. A non-stoichiometric ferrite phase was formed when a sample containing 20 mol% NiO was sintered at 1050~ This phase had two-to three-fold higher conductivity than either Fe203 or the stoichiometric ferrite (NiFe204). The thermoelectric power of this phase indicated a sharp change of charge carriers from n-to ptype near 350 ~ This non-stoichiometric ferrite phase was stable only in a small temperature range and dissociated into ~-Fe203 and stoichiometric ferrite above 1 200~ Samples containing 5 and 10 mol% NiO also had small fractions of this non-stoichiometric ferrite phase when sintered at 1050~