Magnetoplumbite structure

Hexagonal plate-like crystallite Figure 12.11 P-AI2O3 and magnetoplumbite structures (large closed circles = A and B cations small closed circles = M and M cations medium open circles = oxygen ions). 

Fig. 13, Projection of the magnetoplumbite structure M showing spinel (S) and R blocks, the iron-spin orientations (T < TJ, and vertical lines of threefold symmetry parallel to c-axis, after ...

Mngnetoplumbite Figure 1 Ideal semicell of -Al203 and magnetoplumbite structures. 

Also in Fe-containing materials, promoting effect on the formation of the final layered-alumina phase was observed.24 In the completely substituted material BaFe120i9 a monophasic sample with magnetoplumbite structure was obtained at 700 °C. This low formation temperature was related to the greater mobility of oxygen and Ba ions in the lattice of Fe oxides than in A1 oxides. Indeed, the transition from y-+a alumina occurs in Fe oxides at temperatures hundreds of degrees lower than those required for phase transitions in A1 oxides. 

No limits on the content of transition metal ion were found for Fe-substituted systems. As mentioned above, and in line with crystallographic literature,45 a monophasic sample with magnetoplumbite structure was obtained for the completely substituted BaFe O. This sample showed excellent CH4 combustion activity upon calcination at 700 °C, but it markedly deactivated either upon increasing the calcination temperature or upon treatment at high tempera-... 

Fundamental Properties of Hexagonal Ferrites with Magnetoplumbite Structure, by H. Kojima 305... 

Catalytic combustors containing palladium and manganese for gas turbines JP 10047610 Mitsubishi Heavy Industries Ltd. Pd-containing catalyst as an initial stage followed by Mn-containing catalyst with magnetoplumbite structure... 

Hibonite, CA, is found in Ca-rich aluminas and has a magnetoplumbite structure (see Section 7.12). 

Ferrimagnetic ceramics have the spinel (almost exclusively inverse), the garnet, or the magnetoplumbite structure. Table 33.6 lists some examples of ferrimagnetic... 

Crystal structure (Ce, Tb)MgAlnOi9 belongs to a hexagonal system and has the same magnetoplumbite structure as the PbFei20i9 crystal, which has the symmetry of jS-alumina compounds. 

Magnetoplumbite Structure. Ceramics with the general formula M0.6Fe2O3, where M is usually Ba, Sr or Pb, have a hexagonal crystal structure with a unique c axis. These are ferrites (q.v.) and more complex structures with interlayered spinels are possible. 

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