X-ray powder diffractogram

The powder X-ray diffractograms of the composites present the characteristic peaks of the encapsulated zeolite [9]. It is interesting to observe that no characteristic peak of chitosan was present in the XRD patterns of composites. It is clear that the presence of the zeolites has prevented the crystallisation of chitosan when the gel has been dried. This phenomenon has been already observed when the zeolite content reaches a threshold value and has been attributed to a strong interaction between zeolite and chitosan [10],... 

Figure 7. Powder x-ray diffractogram of 80A crystallites of InP in porous sol-gel glass.

Figure 12. (a) Powder X-ray diffractograms obtained by isothermal decompression of VHDA... 

The standard conditions used to evaluate the thermal stabilities of the samples obtained, were the same as reported previously [5] (i) Stable/unstable under heating in static air at 120°C (pre-heated ovens) overnight in unsealed standard sample holders. Approximately 1 g of sample was used, giving layers of ca. 5 mm thickness, (ii) Stable/unstable under heating (heating rate 5°C/min) at 400°C in a flow of dry air (100 ml/min) overnight, the samples (ca. 1 g) were spread out in layers of ca 1 mm in quartz trays. The phases obtained were identified by their powder X-ray diffractograms, recorded before and after the tests. 

Phosphorus-substituted Type B zeolite is not stable to thermal activation. Potassium-exchanged P-B was activated at 350°C and exhibited small-pore (<3 A) and low-capacity adsorption properties. The -exchanged material is crystalline after thermal activation but powder x-ray diffractograms indicate a shift of the lattice spacings. 

The powder X-ray diffractograms of the AlTUD-1 and [WLJ-TUD reveal that the modified sample has structural characteristics identical to the matrix, showing that the the immobilization process did not cause any change in the structure of the support. Both XRD patterns shows one dominant signal, an intense peak around 0.70° 0, indicating the AlTUD-1 is a mesostructured material [17]. 

Figure 36.5. Physical data obtained for mesostructures prepared at 25 °C (left) and at 110 °C (right) with molar TEOS PTMOS ratios of 100 0 and 80 20 a) powder X-ray diffractograms of as-synthesized and extracted samples b) Si HPDEC NMR spectra of as-synthesized samples c) N2 sorption measurements on extracted samples.

Figure 9.5 Example of typical powder x-ray diffractogram measured for an ordered mesoporous silica. The diffraction pattern shows reflections at low 2 theta angles indexed to the cubic laid space group (3D cubic MCM-48 phase). The diffractogram is recorded at low angles with a conventional laboratory instrument.

Figure 3.14 Powder X-ray difFractogram of HgTe nanocrystals ( thiol synthesis ) with corresponding bulk values given as a line spectrum. From Ref. [37].

Kulicke WM, Kull AH, Kull W, Thielkmg H, EngeUiart J, Pannek JB (1996) Characterization of aqueous carboxymethylcellulose solutions in terms of their molecular structure and its influence on rheological behavior. Polymer 37(13) 2723-2731 Kulicke WM, Reinhardt Fuller UGG, Arendt O (1999) Characterization of the flow properties of sodium carboxymethylcellulose via mechanical and optical techniques. Rheol Acta 38 26-33 Kulshreshtha AK, Dweltz NE (1973) Para crystalline lattice disorder in cellulose - 1. Reappraisal of the application of the two-phase hypothesis to the analysis of powder x-ray diffractograms of native and hydrolyzed cellulosic materials. J Polym Sci 11 487 97 Mathur NK, Mathur V (2001) Chemical Weekly, July Edition, 155... 

In order to check the latter point, the powder X-ray diffractogram could be measured for the bulk sample and compared to a calculated spectrum from single crystal data. Visual inspection with a good microscope (with healing to observe different melting points) may also do, often it is quite obvious if all the crystals are of the same type. 

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