Guinier method

X-ray powder diagrams obtained by the Guinier method show the tris (O-ethyl dithiocarbonato) complexes of chro-mium(III), indium(III), cobalt(III), iron(III), arsenic(III), and antimony(III) to be isomorphous. Carrai and Gottardi have determined the structure of the arsenic(III)18 and anti-mony(III)19 complexes. Crystallographic data for the cobalt(III) and chromium(III) ethylxanthate complexes are given by Derenzini20 and Franzini and Schiaffino,21 respectively. 

The compounds Cs2LuCls, Cs3Lu2C19, and Cs3LuC16 are obtained as slightly sintered, moisture-sensitive, colorless powders. They should be stored and handled in a dry box and for longer periods of time sealed under inert gas (N2 or Ar) in Pyrex tubes to prevent hydration. Principal impurities in the samples obtained are most likely oxyhalides such as LuOCl. These are usually not detectable at a sensitivity level of a few percent with the Guinier method. 

Figure 16. Principle of the Guinier method a) Seemann - Bohlin circle b) Monochromator c) Reflection d) Specimen...

Figure 17. Guinier method, showing the four possible relative positions of specimen and monochromator A) Symmetrical transmission B) Asymmetrical transmission C) Symmetrical reflection D) Asymmetrical reflection...

Figure 31. X-ray diffraction paUem of the phase of qui-nacridone. recorded by the Guinier method with Cu K oi radiation...

The radius of gyration of the cluster determined by the Guinier method... 

All the heat treated and as received materials were investigated by XRD (Guinier method) in powdered form to identify the crystalline phases. The results were the same for all the specimens in terms of the phases contained. All the specimens have hexagonal p-Si3N4 grains as the primary phase (- 90-95 vol%) with lattice parameters a= 7.6u8 A and c= 2.9109 A. A second crystalline phase (- 5-10 vol%) were also existed in all the specimens, the heat treated and the as received. The phases are listed below and also references are given of the same phases, previously observed. 

XRD data by Guinier method (Guinier-FiIm CuKoi 4h) of a specimen (1400 C, lOh + 1300°C, lOh) in argon. 

A method for correcting intensities from film data was proposed by Guinier [6] where two films were used. These were separated by a metal filter designed to absorb radiation X and let the more penetrating X/2 radiation through. Subtraction of the intensities on the second film from those on the first gave intensities free from X/2 contamination. 

A model-free method for the analysis of lattice distortions is readily established from Eq. (8.13). It is an extension of Stokes [27] method for deconvolution and has been devised by Warren and Averbach [28,29] (textbooks Warren [97], Sect. 13.4 Guinier [6], p. 241-249 Alexander [7], Chap. 7). For the application to common soft matter it is of moderate value only, because the required accuracy of beam profile measurement is rarely achievable. On the other hand, for application to advanced polymeric materials its applicability has been demonstrated [109], although the classical graphical method suffers from extensive approximations that reduce its value for the typical polymer with small crystal sizes and stronger distortions. 

The method of Simpson and Steinfink (4, 5) which uses liquid scattering functions was employed to take into account the unlocated atoms, assuming that they are uniformly distributed throughout a sphere. Atomic parameters were refined with 235 structure factors corresponding to all reflections with h2 + k2 + l2 <396 except the 111 line. A Guinier-type camera with monochromatized Cu K i radiation was used because of its low background diffusion, to detect the broad diffraction fines of external... 

Samples of purified EuC12 were analysed for europium and chlorine by conventional analytical methods. Calc for EuC12 Eu, 68.18%. Found Eu, 68.1 x +0.2i Cl, 31.80+0.02. X-Ray diffraction patterns of the polycrystalline samples and residues from the vaporization experiments, to which an internal Pt standard (a = 3.9238 +0.0003 A) had been added, were obtained with a Haegg-type Guinier camera and Cu Ka radiation. The lattice parameters and intensities of the diffraction lines were in agreement with those reported (1) for orthorhombic EuC12 (PbCl2 structure). 

If the particles are small, this condition may never be met. It is still possible, however, to determine a fractal dimension for such particles in a scattering experiment. This method makes use of Guinier s law, which ap-... 

In simulating the observed diffraction pattern, however, large values of anisotropic thermal parameters (l/i,) were necessary for As and F atoms. The temperature dependence of the pattern obtained by the Guinier-Simon method (Fig. 8) indicates that the pattern essentially does not change up to 390 K. This hinted that there prevails considerable disorder already at room temperature. The fine structure at 300 K shown in Fig. 8(/>)... 

Fig. 8-29 Guinier-Tennevin method, (a) Perfect crystal. Focused diffracted beam, (b) Bent or polygonized crystal. Enlarged view of nonfocused beam.

A modification of the Guinier-Tennevin method can reveal additional information about a deformed crystal [8.12, 8.13]. If a Seller slit with horizontal plates is placed in the incident beam and the crystal is twisted about a vertical axis, the original vertical-line Laue spot broadens into a striated region composed of fine inclined lines, and the inclination of these lines is a measure of the torsional strain in the crystal (Fig. 8-30(c)). 

Fig. 8-30 Single Laue spots obtained by the Guinier-Tennevin method on a film placed at the focusing position Fof Fig. 8-29(a). Spots (a), (b), and (c) are from the transverse planes of a quartz crystal plate, 37 x 13 x 0.5 mm (a) unstrained, magnification 2X, (b) elastically bent, 2X, (c) elastically twisted, 5X. Spot (d) is from an aluminum crystal after plastic deformation, 4X. Julien et al. [8.12-8.14].

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