Magnesium ferrites

The synthesis [33] of magnesium ferrite (MgFe2C>4) from Fe203 and MgO for catalytic applications has been reported by the use of ultrasound of 20 kHz and power 100 W/cm2. Short range ordering of the alloy of Ni-(0.2-10.3) atomic percent in Cr solid could be affected by 17.5 Hz sound wave at liquid helium temperature (40 K) [34]. 

Kuznetsov VM, Baranov AN, Oleinikov NN (1997) Sonochemical synthesis of Magnesium Ferrite. Dokl Akad Nauk 352(3) 355-357... 

The magnesium ferrites have Ms values ranging from 200 to 40kAm 1 (4nMs = 2500-500 G). Small additions of Mn2+ are found to suppress the formation of Fe2+ which would increase dielectric losses due to electron hopping. As in the case of nickel spinels, the addition of Al3 +, which goes mainly into the B sites, leads to a reduction in Ms. 

Ferromagnetic phenol-formaldehyde sulfonic acid cation-exchange resin has been synthesized by heating a mixture of phenolsulfonic acid and formalin containing magnesium ferrite at 65 °C for 3 h. 

On the mechanism of the selective oxy-dehydrogenation of n-butenes to 1,3-butadiene on magnesium ferrite an FT-IR study. 

Bacon, G. E. Roberts, F. F. (1953). Neutron diffracdon studies of magnesium-ferrite-aluminate powders. Acta Crystallographica, 6, 57-62. 

Corliss, L. M., Hastings, J. M. Brockman, F. G. (1953). A neutron diffraction study of magnesium ferrite. Physical Review, 90, 1013-18. 

The formation of the magnesium ferrite, MgFe204 from MgO and Fe203 is more complex. Instead of a 1 3 ratio in the product phase at the marker s sides, characteristic of a mechanism involving counter-diffusion of three Mg " " ions and two Fe ions, a 1 2.7 ratio has been observed (Carter, 1961). Significantly, the marker was found to be displaced. Fig. 3.14. The reduction of Fe to Fe and a diffusion mechanism Fe 5 Mg " " (with reoxidation of Fe back to Fe in the spinel phase) would lead to a product phase ratio 1 2 at the two interfaces. 

Bon] Bonnickson, K.R., High Temperature Heat Contents of Calcium and Magnesium Ferrites , J. Am. Chem. Soc., 76, 1480-1482 (1954) (Experimental, Thermodyn.,, 7)... 

Mn-Fe alloy catalysts with 32%-40% of Mn have high activities. The addition of 3%-7% of Ru02 into Fe-based catalyst containing cobalt ferrite (25%-359c of Co), magnesium ferrite (20%-25% of Mg), K2O (0.5%-2%) and iron oxide increases activities and heat-resistant properties of catalysts. ... 

V. Sepelak, M. Menzel, K.D. Becker, F. Krumeich, Mechanochemical reduction of magnesium ferrite. J. Phys. Chem. 44, 1411-1415 (2001)... 

Hong, Z. and Song-Ying, C. (2003). Catalytic Performance of Magnesium Ferrite for Hydrox-ylation of 2,3,6-Trimethylphenol, Chin. J. Catal., 24, pp. 635-638. 

Gibson, M. and Hightower, J. (1976). Oxidative dehydrogenation of butenes over magnesium ferrite kinetic and mechanistic studies, J. Catal, 41, pp. 420 30. 

Busca, G., Finocchio, E., Lorenzelli, V., et al. (1996). Infrared study of olefin allylic activation on magnesium ferrite and alumina catalysts, J. Chem. Soc. Faraday Trans. /, 92, pp. 4687-4-693. 

Pure ferrite spinels containing zinc, C.I. Pigments Yellow 119 and Brown 31, or magnesium, C.I. Pigment Brown 11, provide light yellow-brown to light red-brown colors. Zinc ferrites, and to a lesser extent magnesium ferrites, are widely used as heat-stable colorants for thermoplastics. 

---