D-spacing value

Figure 22.3. XRPD diffraction pattern of the fingerprint region (X=1.5418 A d-spacing values 3.0-6.0 A) of various cocoa-butter phases. The y, a and P phases were data from Cameroon cocoa-butter after isothermal crystallization at -10.0°C, 0.0°C and 20.0°C, respectively. The P(V) and P(VI) phases were data from Bahia (Brazil) cocoa-butter, after isothermal crystallization at 22.0°C and from bulk material, respectively (Schenk and Peschar 2004).

Table. 2. d-spacing values (XRD) of different carbon phases... 

We have recently prepared the [Zn-Al-X] and [Zn-Cr-X] series, where X is a mono or bicarboxylate anion with a substitution degree of the divalent metal in the range 0.20 x < 0.50 (El Malki et al. 1991). The basal d spacing values calculated from PXRD study evidences the fact that such anions intercalate perpendicular to the hydroxylated layers with the anionic functions -... 

An XRD pattern of a sample irradiated continuously for 1 h did not contain any nitride peaks. Further analysis with EDS (Figure 7.10) detected the presence of nitride only at a low voltage. Conclusive evidence of nanolayer formation lies in the TEM micrographs of this sample in Figure 7.11. A roughly 10-nm-deep nanolayer with a d-spacing of 2.79 A covers the sample. The standard d-spacing value for MoN, 2.80 A, implies that the nanolayer is likely this compound. 

Note that calculation of using this equation presumes a knowledge of the reference d-spacing value do of the film in the unstressed state. Equations (3.53) and (3.54) together yield the mismatch stress in the film in terms of the measured d-spacing as... 

Alternatively, this same strain can be expressed in terms of the d—spacing values of the diffracting planes as... 

A thin film of a polycrystalline fee metal with 111 fiber texture was deposited onto a relatively thick Si substrate. Nonsymmetric x-ray diffraction measurements showed that the (242) and (242) planes had d—spacing values of 0.8268 and 0.8274 A, respectively. The thin film material is known to be nearly isotropic. The elastic modulus and Poisson ratio of the film material are 70 GPa and 0.33, respectively. 

The d-spacings of native cellulose calculated from X-ray diffractometry profiles are presented in Table 21.5. The d-spacings values obtained were 0.579-0.613 nm for d j and 0.542-0.555 nm for These values indicates that all fibers studied have 1 type cellulose [30, 64], as can be seen in Figure 21.4. These values are significantly different from the d-spacings of the I -nch type celluloses, 0.610-0.617 nm for d j and 0.530-0.541 nm for [16]. In addition, the Z-values for all fibers analyzed confirm that native cellulose in these fibers has a dominance of the monoclinic structure. These data support previous results from diffraction methods stating that the monoclinic structure (Ip) is dominant in the fibers studied [16,64]. 

X-ray powder diffraction patterns of the pristine clay and two initiator-intercalated clay samples are shown in Fig. 5.8. Lamellar periodicity was maintained on the organophilic clay despite the rigorous sonication-centrifugation procedure to intercalate the initiators. By using the Bragg equation, n = 2s sin 6, the d spacing values of these samples were calculated and shown beside each peak. 

On further analysis, the d spacing values seemed to be inconsistent with the steric sizes of the two initiators. The d spacing of bicationic intercalated clay (1.52 nm) is substantially smaller flian diat of the monocationic intercalated clay although their molecular dimensions are comparable (both chain length values are 2.20 nm, as estimated by Chem 3D software). The bicationic initiator molecule possesses charged groups on bofti ends that can have two intercalation possibilities ... 

The combination of these two possibiUties makes the intercalated structure less spatially ordered which accounts for the broadened reflection for this sample as compared with the peak of the clay intercalated by the monocationic initiator. Furthermore, since XRD collects the average information from a large area of a powder sample, a synergic effect of these two possibilities accounts for an intermediate d spacing value. This interpretation is schematically shown in Fig. 

Relatively high content of maghemite in the catalyst prepared from 7-FeOOH was confirmed in two ways. First, the line with 2.52 d spacing value, was the most Intense line in XRO patterns of the catalysts prepared from y-FeOOH, similarly as it was seen in XRO pattern of phase pure Secondly, the extru-... 

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