Magnesium aluminate ferrite

Other, but not all, ceramic crystal structures may be treated in a similar manner included are the zinc blende and perovskite structures. The spinel structure is one of the A B Xp types, which is foimd for magnesium aluminate or spinel (MgAl204). With this structure, the ions form an FCC lattice, whereas Mg ions fill tetrahedral sites and ions reside in octahedral positions. Magnetic ceramics, or ferrites, have a crystal structure that is a slight variant of this spinel structure, and the magnetic characteristics are affected by the occupancy of tetrahedral and octahedral positions (see Section 20.5). 

Table 2.3 lists some phases containing MgO that are in varying degrees relevant to cement chemistry. It is not a complete list of phases with essential MgO in the CaO-MgO-AljOj-SiOj system. As seen in Chapter 1, some MgO is also taken up by all four of the major clinker phases, typical contents being 0.5-2.0% for alite, 0.5% for belite, 1.4% for the aluminate phase, and 3.0% for the ferrite phase. Magnesium oxide (periclase), like calcium oxide, has the sodium chloride structure it is cubic, with a = 0.4213 nm, space group Fm3m, Z = 4, = 3581 kgm (S5) and refrac-... 

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

Effects of common minor and trace elements derived from recycling waste materials in fuels and as raw materials for clinker production, as well as cement hydration, are summarized by Uchikawa and Hanehara (1997). Crystal size and optical property variations in clinker phases (alite, belite, aluminates, and ferrite), and their hydraulic reactivities, are shown to be related to concentrations of sulphm, magnesium, phosphorous, fluorine, chlorine, chromium, manganese, zinc, and many other elements. The cement industry is based in crystal chemistry. 

Koe] Koehler, M.F., Barany, R., Kelley, K.K., Heats and Free Energies of Formation of Ferrites and Aluminates of Calcium, Magnesium, Sodium, and Lithium , Report of Investigations, US. Bureau of Mines, 5711, 1-14 (1961) (Experimental, Thermodyn.,, 32)... 

Organotitanates, aluminates, zirconates and zircoaluminates can also act like silanes as adhesion promoters. They perform similar functions, but unlike silanes there is no need for water molecules to be eliminated. These other treatments bond the polymer to the filler surface by a chemical bond involving proton co-ordination, and they can also be used with fillers that are not receptive to silanes, such as calcium carbonate, carbon black and barium sulfate, as well as barium ferrite, magnesium hydroxide, aluminium trihydroxide, titanium dioxide, talc and the nanoclays. 

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