Samples crystallinity

Ore. The assay of mercury ores is not simple, owing to the difficulties encountered in obtaining representative ore samples. Crystalline cinnabar is extremely brittie causing it to break loose from adjacent rock and fall into the sample being collected. This uncontrollable salting of the sample can give results as much as several hundred percent over the actual mercury content of the sample. 

Cellulose pyrolysis kinetics, as measured by isothermal TGA mass loss, were statistically best fit using 1st- or 2nd-order for the untreated (control) samples and 2nd-order for the cellulose samples treated with three additives. Activation parameters obtained from the TGA data of the untreated samples suggest that the reaction mechanism proceeded through an ordered transition state. Sample crystallinity affected the rate constants, activation parameters, and char yields of the untreated cellulose samples. Various additives had different effects on the mass loss. For example, phosphoric acid and aluminum chloride probably increased the rate of dehydration, while boric acid may have inhibited levoglucosan... 

Phase purity of the sample. Crystalline impurity phases present in a powder sample (e.g. residual amounts of starting materials from a synthetic procedure) contribute additional peaks to the experimental powder XRD pattern. As a result, the pattern may look substantially different from that of a pure sample of the main phase. Clearly, careful inspection should be carried out to assess the presence of impurity phases, particularly with regard to residual amounts of unreacted starting materials. 

Figure 8 illustrates the transformations induced on the surface structure of HT materials after 10 days of corrosion. The amorphous gel layer that appears during corrosion is observed on most HT samples and reveals pits, holes, and corrosion paths from case to case. For many samples, crystalline secondary phases in the 1-10 pm range cover the altered surface, and spallation/cxfoliation of the gel layer is observed or at least suggested in several instances, indicating that corrosion is a discontinuous process, even under static conditions. 

Traditionally, X-ray absorption edge measurements have been used to determine oxidation states of metals in complex materials. The extended X-ray absorption fine structure (EXAFS), on the other hand, provides structural information such as bond distances and coordination numbers even with powdered samples, crystalline or amorphous, the fine structure essentially resulting from short-range order around the absorbing atom. The technique is also useful for studying solid surfaces (SEXAFS). The observation of fine structure beyond the K-absorption edges of materials dates back to... 

Sample Crystallinity NFAI content Surface area Micropore volume Coking rate Rate constant ... 

We should emphasize that sometimes, not all profile parameters should or could be routinely refined due to the quality of a particular pattern and/or sample crystallinity. For example, U, V, and Wparameters, which define the instrumental part of the FWHM as a function of Bragg angle, can be kept fixed assuming that their values in the instrumental parameters file were... 

X-ray diffraction of freeze-dried products was determined to observe sample crystallinity. The determinations were carried out with the aid of a JEOL Model JDX-8030 x-ray diffractometer. 

Doverspike et al. [66] reported a deuteron NMR orientational lineshape study of perdeuterated (99%) PVDF and the copolymer of vinylidene fluoride with tetrafluoroethylene having 80 mol% VDF. The experiments examined only the crystalline part of the drawn and poled samples (crystallinity of P(VDF-co-TFE) estimated by XRD to be 50%). The maximum remanent polarisation attained with deuterated PVDF homopolymer film was... 

The study was conducted on sample Si-0.16. The experiments with NaCl or La(N03>3 solutions at room temperature or 400 K give either no exchange or amorphisation of the materials. After exchange with a NH4NO3 solution at a pH of 4 the X ray diffraction does not detect a change in the sample crystallinity. The unit cell parameter is decreased from 24.76 ( 0.01) A to 24.65 ( 0.01) A. A similar modification was already observed after the template decomposition upon heating at 875 K (2). 

The effect of crystallinity of the sample is rather difficult to evaluate because of the definition of the term degree of crystallinity Carthew (91) defined the latter, in the case of kaolin samples, as the perfection of crystal orientation and not the size of the crystal. Using five different samples of kaolin, he found that the area of the endothermic dehydration peak decreased with a decrease in sample crystallinity. The peaks appeared to be sharper as the degree of crystallinity of the sample increased. This effect of crystallinity was said to be similar to that of change in particle size, and could probably be explained in a similar manner. 

Sample Crystalline Phases Raman shift (cm" ) Raman attributions... 

The sprue-plane is called the xy-plane. Results measured on four different TMA samples taken from an injection moulded sample, crystallinity 44 %wt.)... 

Colour b values are influenced by sample crystallinity and are not directly comparable between flakes and pellets. 

Sample crystallinity can be estimated from the x-ray patterns by plotting the density of the scattered beam against the angle of incidence. If this can be done for an amorphous sample and a corresponding sample that is highly crystalline, a relative measure of crystallinity for other samples of the same polymer can be obtained. In Figure 10.8 the shaded portion is the amorphous polypropylene, whereas the maxima arise from the crystallites. 

The chemical level This deals with information on the fine structure, namely, what type of monomer constitutes the chain and whether more than one type of monomer (copolymer) is used, i.e., the parameters that relate ultimately to the three-dimensional aggregated structure and influence the extent of sample crystallinity and the physical properties. 

The morphology of the films was examined by means of an optical microscope. It was established that under the conditions described above the CT complex starts to crystallize from the nuclei formed at the edges of the solution layer during the initial stage of film solidification. As the zone solidification moves throughout the sample, crystalline columns of the complex, nearly parallel to each other, are formed at the solidification front. An example of the structure formed in this way is shown in Fig. 2. It can be seen from the micrographs that even if a small number of nuclei is formed at the edge of the sample, a dense system of oriented crystalline paths is obtained in the inner part of the sample. 

XRD cryptography is a very useful method to determine polymer crystalhnity. The sample is bombarded with X-rays while rotating. Interaction of the X-rays with the material generates diffraction patterns that are used to describe sample crystallinity. XRD follows Bragg s law in that the reflected X-rays... 

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