Maghemite Curie temperature

A related system is that of the titanomaghemites, Fe2Ti05, which are formed by oxidation of the titanomagnetites. These are spinels with vacancies in some of the cation positions. The detailed distribution of cations and vacancies is not fully understood a discussion of the different models and possibilities is given by Lindsley (1976). A non-linear relationship between the unit cell size of titanomaghemite (a = 0.8483 nm) and that of maghemite (a = 0.835 nm) was matched by a non-linear increase in the Curie temperature from 80 to 450 °C (Dunlop Ozdemir, 1997). 

Maghemite is ferrimagnetic at room temperature. Measurement of Tc is difficult because maghemite transforms to hematite at temperatures above ca. 7-800 K. The Curie temperature has been estimated as lying between 820 K and 986 K (Murad, 1988). 

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