Pseudo-brookite

Iron metaniobates(iv) with structures of the natural minerals, ilmenite and pseudo-brookite have been prepared by direct reaction of the oxides under vacuum at 1000—1100°C. The compounds are stable in air up to 500°C, but are oxidized at higher temperatures.326 a-Sr3Fe07 x has been found to be isostructural with Sr3Ti07.327 Synthesis and thermal decomposition of iron(m) normal selenite mono-or tri-hydrate, Fe203,3Se02,xH20 (x = 1 or 3) have been reported.328... 

X-Ray Diffraction. Diffractograms of the catalysts show that crystalline phases containing iron are formed upon calcination. In catalysts supported on rutile hematite (a-Fe202) is formed. When the iron phase is applied onto anatase, pseudo-brookite Fe2TiOs) is observed. The formation of pseudobrookite has previously been observed to take place only at 800°C for P-25 titania impregnated with iron solutions [71, but also at lower temperatures (550°C) when samples were prepared by co-precipitation or impregnation of freshly precipitated 100% anatase. In those samples, iron was in intimate contact with titania [8]. The results obtained with XRD indicate that iron is in intimate contact with the support indeed. 

Maloney, J., Titanate Pigments Gol-ored Rutile, Priderite and Pseudo-brookite Structured Pigments, in High Performance Pigments (Ed. H. Smith), Wiley-VGH, Weinheim, 2002... 

Fe2Ti0s, pseudo-brookite, has orthorhombic symmetry and contains Fe + in a distorted octahedral environment [20]. The quadrupole splitting at room temperature is 0-75 mm s [108]. 

PB) indicates the presence of pseudo brookite in these specimens. 

Percentages of the crystal phases present were determined from integrated XRD peak heights according to the method of Criado et.al [10). Additionally, the formation of pseudo-brookitc is apparent in specimens of greater than 2 atom% nominal iron content calcined at 1073K. Evidence of pseudo brookite is also obtained in the specimen TF/SP/10/973. 

The three pertinent crystal classes are differentiated in Table 6.3 by their unit cell lattice constants. Rutile and priderite have tetragonal unit cells, while pseudo-brookite has an orthorhombic unit cell. They are more thoroughly characterized in the PDF database [5]. 

In anatase, the TiO octahedra share four edges to form a pseudo-tetragonal framework structure, and in brookite the octahedra share three edges. Each... 

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