XRD analyses

Approximate Values in Units of Percent The particle size distribution in a total dust sample is unknown and error in the XRD analysis may be greater than for respirable samples. Therefore, for total dust samples, an approximate result is given. (4) Nondetected A sample reported as nondetected indicates that the quantity of quartz (or cristobalite) present in the sample is not greater than the... 

A bulk sample is the last choice and the least desirable. It should be submitted "for laboratory use only" if there is a possibility of contamination by other matter. The type of bulk sample submitted to the laboratory should be cross-referenced to the appropriate air samples. A reported bulk sample analysis for quartz (or cristobalite) will be semi-quantitative in nature because (1) The XRD analysis procedure requires a thin layer deposition for an accurate analysis. (2) The error for bulk samples analyzed by XRD is unknown because the particle size of nonrespirable bulk samples varies from sample to sample. 

Iron impregnated on activated carbon was used as catalyst for the direct synthesis of phenol from benzene. The effect of Sn addition to the catalyst was studied. The prepared catalysts were characterized by BET, SEM and XRD analysis. The catalyst 5.0Fe/AC showed good activity in the conversion of benzene and addition of Sn seemed to improve the selectivity of phenol in the reaction. 

XRD analysis of the solid product showed three main peaks at 28.5 , 47.4 and 56.3 , which indicated that pure crystalline CuCl was formed [3]. Several well-known dispersants polyvinyl pyrrolidone (PVP), sodium hexameta phosphate (SHP), the sodium salt of EDTA (EDTA-Na), sodium dodecyl sulfonate (SDS), and sodium dodecyl benzene sulfonate (SDBS), were introduced to obtain a highly dispersed catalyst. The X-ray patterns obtained with these were basically the same as the patterns obtained with the solids prepared in the other experiments described here. 

Reaction (2) was also studied using the different catalysts. Before exposure to CH3CI, the contact masses were subject to XRD analysis. In the XRD patterns of the catalysts with higher activities for the Rochow direct process, the XRD peaks of the Cu-containing species were weaker and broader when normalized to the silicon peaks (silicon was used in excess). This suggests that some undetectable species were formed and the catalytic species were well-dispersed. This agrees well with the view of Lieske and co-workers [5]. 

The Fe-B nanocomposite was synthesized by the so-called pillaring technique using layered bentonite clay as the starting material. The detailed procedures were described in our previous study [4]. X-ray diffraction (XRD) analysis revealed that the Fe-B nanocomposite mainly consists of Fc203 (hematite) and Si02 (quartz). The bulk Fe concentration of the Fe-B nanocomposite measured by a JOEL X-ray Reflective Fluorescence spectrometer (Model JSX 3201Z) is 31.8%. The Fe surface atomic concentration of Fe-B nanocomposite determined by an X-ray photoelectron spectrometer (Model PHI5600) is 12.25 (at%). The BET specific surface area is 280 m /g. The particle size determined by a transmission electron microscope (JOEL 2010) is from 20 to 200 nm. 

Typical examples of XRD analysis of copper powder recovered in the inverse fluidized bed electrode reactors can be seen in Fig. 2, where the ratovered copper powder was almost pure. Effects of fluidized particles on the size distribution of copper powder recovered in the reactors can be seen in Fig. 3. Note that the addition of a small amount of fluidized particles could decrease the size of recovered copper powder, but a further increase of particle amount could increase the size of copper powder, compared with that without fluidized particles. This can be due to that the added particles(up to 1. Owt.%) can contact with the cathode plate frequently, which could be resulted in the effective cut of the copper powder growing perpendicular to the surface of the cathode plate. 

Fig. 2. Typical example of XRD analysis of copper powder recovered in inverse fluidized bed reactors(LAc=0.015m, 1=3.0 A/dm W=1.0wt.%).

To produce amorphous VOPc, 5.0 g of crude VOPc was added into 250 ml of concentric H2SO4 solution, and then the mixture was stirred slowly at 5 °C for 2 h. After acid-treatmcait, cake was collected by filtration, washed with distilled water until washing solution became neutral, then dried at 70 °C over 24 h in a dry oven. To produce fine crystal VOPc, 5 g of amorphous VOPc was added into 90 ml of NMP/H2O solution, and then stirred slowly at 80 C for 1 h. After recrystallization, cake was collected by filtration, washed with methanol, and then dried. All polymorphs were assayed by XRD analysis. 

The XRD data and Zn/Cu ratio are also given for a reference aurlchalclte specimen reported In the literature ( ). All d-spaclngs In the mineral and synthetic aurlchalclte matched the literature values within the lattice volume changes (<2%) reported In Table 1. Over 30 XRD peaks were used In the XRD comparisons. The XRD analysis established that the structure of the mineral and synthetic aurlchalclte was essentially Identical. The only distinguishing features were the higher Cu content and the 1.6Z smaller unit cell volume of the mineral sample compared to the synthetic sample. 

X-ray dififtaction (XRD) analysis of the freshly calcined catalysts as well as samples used for several hours in the isomerization reaction, only presented the peaks corresponding to the tetragonal form of zirconia. At the same time, for the silica series, XRD confirmed the presence of NiO on the unsulfated catalysts and NiS04 on the sul ted ones. However, XRD did not show any evidence of any of these species for the zirconia series, probably due to their high state of dispersion. Similarly, the XPS data clearly showed the presence of NiO and NiS04 on the unsulfated and sulfated silica-supported catalysts, respectively, but they were not conclusive in the case of zirconia series since both sulfate and oxide species were observed. 

Komrska Satava (1970) showed that these accounts apply only to the reaction between pure zinc oxide and phosphoric acid. They found that the setting reaction was profoundly modified by the presence of aluminium ions. Crystallite formation was inhibited and the cement set to an amorphous mass. Only later (7 to 14 days) did XRD analysis reveal that the mass had crystallized directly to hopeite. Servais Cartz (1971) and Cartz, Servais Rossi (1972) confirmed the importance of aluminium. In its absence they found that the reaction produced a mass of hopeite crystallites with little mechanical strength. In its presence an amorphous matrix was formed. The amorphous matrix was stable, it did not crystallize in the bulk and hopeite crystals only grew from its surface under moist conditions. Thus, the picture grew of a surface matrix with some tendency for surface crystallization. 

Scanning electron micrographs of fracture surfaces revealed the presence of both amorphous and crystalline phases which corresponded to results from XRD analysis (Figure 6.12). What is of interest is that the crystalline phase is MgHP04.3H20 and not Mg(H2P04)2.2H2O or... 

The chief problem in studying the chemical nature of AB cements is that many are essentially amorphous, so that the powerful tool of X-ray diffraction (XRD) analysis cannot be used. Some AB cements do exhibit a degree of crystallinity, but rarely in significant amounts indeed, complete crystallinity is usually a sign that the reaction product is not cementitious. The literature contains numerous examples of workers being misled by the results of XRD analysis into neglecting the presence and significance of the amorphous phase. 

XRD analysis perfected by the application of Rietveld method [11,12] provided an average metal nanocluster diameter equal to 3.3 nm (Table 3). 

XRD analysis on sulfated ash residue of new additive packages in lubricating oils has indicated the presence of nonstoichiometric mixed salts of the elements Mg, Ca, Zn, P and B [60],... 

Any residual doubt about the actual 7r-stabilization of such carbanions, that is, the question concerning the importance of resonance structure 52a, has been decisively banished by an XRD analysis of the lithium bis(12-crown-4) salt of dimesityl(methyl)borane (54).56 Noteworthy are the slightly elongated mesityl C—B bonds at 1.617 A (over those in Mes2BMe at 1.586 A) and the pronouncedly shorter methylene C—B bond at 1.444 A. Moreover, the C2BCH2 core atoms lie essentially in a plane. All these data support the view of 54 as a borataethene, just as structure 52a would imply. 

A derivative of 62 has been prepared, as shown in Scheme 2, and an XRD analysis of lithium salt 63 has been carried out.63 The mesityl B,—C bond length is 1.339 A and the mesityl B2—C bond is 1.492 A, while the B —C—B2 linkage is almost linear (1.765(5) A). These findings support the conclusions that the B,—C bond has considerable triple bond character, since it is 0.10 A shorter than that in the Mes2B=CH2 anion (54) and the B2—C bond has significant double bond charracter, being about 0.09 A shorter than a B—C bond. 

The resulting crystal proved amenable to a conclusive XRD analysis. As shown in Eq. (26), the C—C ring bond is lengthened over what it is in the structurally similar cyclopropene (1.304 A) and the B—C bonds shortened relative to the electronically analogous bond in trivinylborane (1.558 A). Thus, one can safely conclude that there is extensive 7r-electron delocalization and Hiickel aromatic character in the borirene ring. 

Electronically related to such borirenes are the salts of the dianion of 1,2-di-tert-butyl-3-[bis(trimethylsilyl)]methyl]-l, 2-diborirane.85 An XRD analysis of the dipotassium salt (86a,b) uncovered shortened B—B (1.58 A) and B—C (1.50 A) bonds, as suggested by resonance contributions 86a and 86b. Salt 86 can be considered to have largely a 2- r-electron Hiickel aromatic ring. 

It might be amusing to conclude this section by noting the structure that a l,2,3,4-tetrahydro-l,2,3,4-tetraborete assumes. Treatment of ferf-butylboron difluoride with sodium-potassium alloy (Eq. 28) gives a derivative (92) of such a system, whose XRD analysis reveals that the nuclei assume a maximally folded structure—namely a tetrahedron.91... 

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