Debye-Scherrer method

Phase identification was done on the basis of both d-spacing and the peak height intensity of all the x-ray lines. These values were compared with values obtained for the end-member (unsubstituted) compounds and also calculated by means of the Lazy-Pulverix computer program (9). Precision lattice parameters were obtained by the Debye-Scherrer method with a 114.6 mm dia. camera and filtered Cr Ka radiation standard least-squares methods were used. 

University in Ithaca. Nobel Prize in 1936 for contributions to the knowledge of molecular structure based on his research on dipole moments, X-ray diffraction (Debye-Scherrer method), and electrons in gases. His investigations of the interaction between ions and electric fields resulted in the - Debye-Huckel theory. See also -> Debye-Falkenhagen effect, - Debye-Huckel limiting law, - Debye-Huckel length, - Debye relaxation time. 

There are several experimental techniques for realizing the diffraction conditions, the most powerful of which depends on having a single crystal of the substance to be studied see Exp. 46. In the present experiment we are concerned only with the Debye-Scherrer method (often called the powder method), which does not make use of a single crystal but rather of a powder obtained by grinding up crystalline or microcrystalline material. This powder eontains crystal particles of a few micrometers in size. 

The Raman samples themselves were used to obtain powder photographs by the Debye-Scherrer method. 

Table 2. X-ray Powder Data (Debye—Scherrer Method, Cu Ka Radiation, Ni Filter) for AgsAsFn"...

Figure 2.12 The Ewald sphere method illustrates the ring pattern of diffraction from a powder specimen. The Debye ring recorded by the Elull-Debye-Scherrer method results from randomly oriented crystals in the powder specimen, in which reciprocal lattice points of (hkl) touch the Ewald sphere surface in various directions to form individual rings. It is equivalent to rotating a reciprocal lattice along an incident beam axis. (Reproduced with permission from R. Jenkins and R.L. Snyder, Introduction to X-ray Powder Diffractometry, John Wiley Sons Inc., New York. 1996 John Wiley Sons Inc.)...

The specimen in the Debye-Scherrer method has the form of a very thin cylinder of powder placed on the camera axis, and Fig. 4-18(a) shows the cross section of such a specimen. For the low-an le reflection shown, absorption of a particular ray in the incident beam occurs along a path such as AB at 5 a small fraction of the incident energy is diffracted by a powder particle, and absorption of this diffracted beam occurs along the path BC. Similarly, for a high-angle reflection, absorption of both the incident and diffracted beams occurs along a path such as DE -I- EF). The net result is that the diffracted beam is of lower intensity than one would expect for a specimen of no absorption. 

Exact calculation of the absorption factor for a cylindrical specimen is often difficult, so it is fortunate that this effect can usually be neglected in the calculation of diffracted intensities, when the Debye-Scherrer method is used. Justification of this omission will be found in Sec. 4-11. 

The temperature effect and the previously discussed absorption effect in cylindrical specimens depend on angle in opposite ways and, to a first approximation, cancel each other in the Debye-Scherrer method. In back reflection, for... 

Debye-Scherrer method. The film is placed on the surface of a cylinder and the specimen on the axis of the cylinder. 

Fig. 6-2 Geometry of the Debye-Scherrer method, diffraction cone.

The x-ray diffraction results are obtained by the Debye-Scherrer method using molybdenum ka radiation, the time of exposure in each case being 6 hrs. 

A) Schematic of the Debye-Scherrer method, developed in 1916, for X-ray diffraction of powders (polycrystdlline samples). Each characteristic interplanar spacing in the crystal gives rise to a cone of diffracted X-rays, segments of which are captured on the film strip placed inside the camera. 

Debye-Scherrer method A method of X-ray diffraction in which abeam of X-rays is diffracted by material in the form of powder. Since the powder consists of very small crystals of the material in all possible orienta-... 

The x-ray phase analysis of some of the alloys was conducted by the Debye-Scherrer method, using copper radiation for an anode current of 18 mA, the exposure time was prox-imately 10 h. 

Debye-Scherrer method A method used in X-RAY diffraction in which a crystal in powder form is exposed to a beam of monochromatic x-rays. Because the crystal is in powder form all possible orientations of the crystal are presented to the x-ray beam. This has the result that the diffracted x-rays form cones concentric with the original beam. The Debye-Scherrer method is particularly useful for determining the lattice type of a crystal and the dimensions of its unit cell. The method was first developed by Peter Debye and Paul Scherrer. 

Figure 6.4 The Debye-Scherrer method for taking powder photographs. The angle RSX is 20, where 0 is the angle of incidence on a set of crystal planes (17).

Since a semicrystalline polymer sample can be assimilated to a microcrystaUine powder in which chain segments of irregular conformation would play the role of amorphous cement (binding material), the Debye-Scherrer method can be used for such determination. A typical diffraction pattern is presented in Figure 6.23. The degree of crystallinity is equal to the ratio of the diffracted intensity k to the total intensity transmitted in the form of a coherent radiation /, integrated over the reciprocal lattice ... 

Experimental Techniques Orientation of the crystalline phase in polyethylene films has been mainly characterized by WAXD [82-98]. In the first studies, the Debye-Scherrer method was employed with a flat-film camera [82-84]. This technique was still used in further work because of its rapidity and its simplicity [87,88,93, 95-98]. 

It was well known that Williamson-Hall method is more accurate method to calculate crystallite size as compared to Debye-Scherrer method. The Fig. 2 represents the Williamson-Hall (W-H) plot for YP04 Eu nanostructure phosphor. As shown in Fig. 2, the Y- intercept is 0.0027 taking X as 0.154 nm, the grain size was found to be around 62 nm. The calculated particle size was in good concurrence with the Debye-Scherrer data. The small variation in the size of grains calculated by Debye-Scherrer and W-H method was due to the fact that in Debye-Scherrer formula strain component was assumed to be zero and the diffraction peak broadening was assumed to be due to reduced grain size only. 

For determining the structure of semicrystalline polymers, we use the Debye-Scherrer method, in which a narrow beam of x-rays enters a cylindrical film cassette through a collimator and hits the sample situated at the center of the cassette. The resulting diffraction pattern is recorded on the photographic film, which is analyzed with the help of a microdensitometer. Typically, for unoriented, crystalline samples, the diffraction pattern is a series of concentric circles. If, however, the crystal axes have a preferred orientation, the rings change to arcs or... 

---