Hematite electron micrographs

Figure 6 shows transmission electron micrographs of Au particles supported by (a) monocrystalline ellipsoidal (B), (b) monocrystalline pseudocubic, and (c) monocrystalline platelet-type hematite particles (see also Figure 5 for Au particles on polycrystalline ellipsoidal (A) particles). Figure 7 shows Au particles deposited on (a) a-FeOOH, (b) P-FeOOH, (c) ZrOj (A), (d) ZrOj (B), and (e) Ti02 (anatase). 

Figure 5. Transmission electron micrographs of Au nanoclusters deposited on the surfaces of the polycrystalline ellipsoidal hematite particles. The left photograph is a close-up view of the right one.

Fig. 4.n Replica (upper) and scanning force electron micrograph (lower) of goethite grown epitaxically on hematite cores ( upper see Cornell, 1985 lower Barron et al. 1997,with permission). 

Fig. 14.3 High resolution electron micrographs of the thermal transformation of goethite to hematite showing (Gt[001]//[Hm[210] orientation. Upper Gradual development (a d) of slit pores along Hm[001]. Lower Largely transformed region along the (Gt[001]//[Hm[210] orientation. Electron diffraction patterns in the in-...

Fig. 1417 Transmission electron micrographs documenting the transformation of ferrihydrite to hematite (Fischer. Schwert-mann, 1975 with permission).

Fig. 16.2 Scanning electron micrograph of an association between goethite (go) and hematite (he) in laterite from Cameroon (Muller, 1987 courtesy).P. Muller with permission).

Fig. 16.19 Electron micrographs of natural associations between iron oxides and other soil minerals, a) Goethite (Co) crystals epitaxially grown on kaolinite (K) flakes (TEM) from a late-rite in Cameroon (courtesy J.P. Muller see also Boudeulle, Muller, 1988). b) Association of kaolinite (k), goethite (go) and hematite (he) in an Oxisol, Cameroon (SEM) (1987 courtesy J.P. Muller see Muller, Bocquier, 1986). c) Goethite accumulation between kaolinite...

Fig. 1.3.11 Electron micrographs of the Liltrathin sections of (a) pseudocubic and (b) peanut-type hematite particles. (From Ref. 21.)...

Fig. 13.1.8 Transmission electron micrograph of monodisperse spindle-type hematite particles.

FIGURE 8.6 Electron micrograph of monodispersed spindle-type hematite particles prepared by hydrothermal reaction of FeClj solution in the presence of small amounts of phosphate ions. 

Fig. 5-15. Electron micrograph replica of acicular goethite outgrowths on a hematite eore. The crystals grew from ferrihydrite at pH 11.7 and 70 °C in the presence of 10 M maltose in 24 h. Bar =100 nm. (see Cornell, 1985).

Al-substituted hematites were also produced from Al-containing 2-line ferrihydrite at room temperature and pH 4-7, although at a much lower rate (months to years) (Schwertmann et al. 2000). For the same initial Al/ (Al+Fe) ratios the substitution is lower than at higher temperatures. Electron micrographs show rhombic crystals at low substitution (Fig. 10-5 a), identical to unsubstituted ones, and framboidal or spindle-shaped crystals with a grainy or layered interior at higher substitution (Fig. 10-5b). The latter diffracted X-rays as single crystals. 

Fig. 15-1. Scanning electron micrographs of goethite- (upper) and hematite-eoated (lower) cristobalite produced at pH 2.5. The amounts of iron oxide at-taehed are 14.4 (goethite) and ca. 1 mg (hematite) per g cristobalite sand. (Courtesy A. Scheidegger). (From Scheidegger et al., 1993 with permission.)...

Properties >98% hematite [38], contains 0.3 mol% of Cl with respect to Fe, which is not removable by water washing, cubic particles [1394], BET specific surface area 34 m-/g [38], average size 120 nm, uniform particles [38], electron micrograph available [1394]. 

Properties Different shapes and structures (hematite or (3-FeOOH) were obtained, depending on the experimental conditions. TEM and SEM images available [1374]. BET specific surface area 10.4 mVg, length 1 pm, width 300 nm [1622], electron micrograph available [586]. 

FIGURE 16.3-2 ( ) Scanning electron micrograph of u hematite sample on which spill analysis was conducted, (b) EDAX analysis of spot G shown in part (a). Analysis of spot E was similar to that obtained for spot G. (< ) EDAX analysis of spot H as shown in pari (a). (After Kulkami and Somasundaran 1 courtesy of Elsevier Seuijoia S.A.. Lausanne. Switzerland.)... 

Fig. IV-14. Electron micrographs of some characteristic monodispersed colloidal particles a - zinc sulfide (ZnS), b - hematite (a-Fe203), c - cadmium carbonate (CdC03). Courtesy of Professor Egon Matijevic...

Figure 7 Scanning electron micrograph (SEM) of platelike hematite particles produced by transformation from precipitated Fe(OH)3 at 200°C.

Figure 4.15 Transmission electron micrographs of hematite in the presence of schizophyllan under conditions of rapid kinetics. Schizophyllan/hematite ratio 3.79, pH 4.5, /= 1 mmol dm". The three-dimensional floe obtained by computer simulation (optimum conditions) explains the presence of a local linear order observed in the hematite Hoc due to the presence of rigid...

Fig. 4.4 Scanning electron micrograph (left) of the edge of a porous electrode made from sintered Fc203 sols on a conducting cassiterite (Sn02) support (magnification 5,800 times). Absorption spectrum of the hematite electrode and quantum efficiency as a function of wavelength (right) obtained in 0.1 M NaOH at 1.4 V vs. RHE when illuminating the electrode through the substrate (SE) and directly onto the interface with the electrolyte (EE). Note that the scale of the IPCE values differs with a factor of 100 in the two cases. From [67] used with permission...

X-ray diflEraction (XRD) analysis has been a useful tool to check the presence of minerals (viz., Mullite, Hematite, Magnetite and ot-Quartz) as the main crystalline phase in the fly ash and its zeolites, in addition to the presence of amorphous glassy phase [16, 38]. Furthermore, micrographs obtained by scanning electron microscopy (SEM) of the fly ash and its zeohtes, as depicted in Fig. 2.6a, have been found to be a useful tool for demonstrating the shape and grain size of constituent minerals (refer Table 2.5 [8, 24]). 

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