Magnetite Curie temperature

Magnetite is ferrimagnetic at room temperature and has a Curie temperature of 850 K. The two different cation sites in the structure - tetrahedral (A) occupied by... 

Substitution of Fe with Cd and Zn " " ions in tetrahedral sites of magnetite reduced the HMF of both the octahedral and tetrahedral iron [340]. Substitution with Cr ions at octahedral sites in magnetite reduced the HMF values of iron at octahedral as well as at tetrahedral sites [250]. This substitution also reduced Curie temperature from... 

Evidence for the presence of A1 dissolved in the magnetite phase has been found by X-ray powder diffraction [27,28, 38-42, 53] and by chemical analysis of powders of varying particle size [54]. The solubility of A1 in the (Fe,Al)3 04-phase has been determined to be 30 atom% A1 [55] from measurement of the Curie temperature and 50 atom % Al[55], or 67 atom % Al[39] from measurement of the X-ray powder diffraction lattice constant. Other studies have indicated homogeneous solution of A1 in magnetite, at least for small amounts of A1 [56] and not too high temperatures [57]. 

C to 5.2 at 585 °C). It is the Curie point of magnetite, which forms at 572 °C, as the DTA curve demonstrates. The values of the measured dielectric constants do not accurately correspond to the real respective constants of the mixture while being heated with microwaves, because the heating rates are much higher and a number of different mineralogical phases are formed where topically high temperatures are achieved. However, the measured constants approach the real values in parts of the sample that were heated relatively smoothly with microwaves, that is, the external surface. 

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