Bragg-Brentano diffractometer

Fig. 14. Focusing schemes in powder diffraction (a) conventional para-focusing Bragg-Brentano diffractometer (b) parallel-beam diffractometer using a...

FIGURE 1.25 Sample irradiation in a Bragg-Brentano diffractometer. 

In the case of testing a powdered sample in a Bragg-Brentano diffractometer, the sample has the shape of a flat plate located parallel to the reflecting plane, making equal angles with the incident and diffracted beams then, if we have a single phase in the sample, the absorption factor is given by [21]... 

Figure 2.12 Photograph of a Bragg Brentano diffractometer equipped with a pre sample monochromator (on left) and scintillation detector (on right). Sample stage and detector move in the vertical plane about a horizontal axis in the ratio 1 2. The sample is spun about an axis normal to the flat plate. Although this instrument dates from the early 1990s, the latest generation of laboratory Bragg Brentano dilfractome ters still function in a similar manner to the one shown here.

Figure 6.24 Bragg Brentano diffractometer with incident beam monochromator.

The results of these measurements are shown in Figure 2.37. Note how the use of a strictly parallel beam can greatly improve the diffractometer s angular resolution. As we will see later on, the resolution of this diffractometer is equivalent to that obtained with Bragg-Brentano diffractometers in the high resolution configuration. 

Figure 2.50. Diffraction pattern of a sample of cerium oxide powder obtained with a Bragg-Brentano diffractometer equipped with a copper anode source and a nickel filter [BAL 04]...

Figure 2.51. Path of the X-ray beams in a Bragg-Brentano diffractometer equipped with a front monochromator...

Quite clearly, the Bragg-Brentano diffractometer leads to the best angitlar resolution. The peaks which are split in two, specific to the Kotj and Kot2 emission peaks, are plainly visible in the first pattern. The peaks in the second pattern are not split, but they are clearly wider than those obtained with the Bragg-Brentano diffractometer. 

Bragg-Brentano diffractometer, front curved quartz monochromator, front Sober slits... 

Figure 4.9. Diffraction patterns of the compound NaBifSb jO]j. The pattern shown in (a) was produced by using a Bragg-Brentano diffractometer equipped with graphite back monochromator. The pattern shown in (b) was produced with a Debye-Scherrer-Hull system equipped with a quartz front monochromator...

Figure 2S. X-ray diffraction pattern of the y-phase of qui-nacridone. recorded in a Bragg - Brentano diffractometer with Cu K X radiation...

Fig. 9.10 Diagram of a powder Bragg-Brentano diffractometer geometry...

TEM observations have been carried out with a Fei Tecnai F20 and XPS analyses were performed on a Kratos Axis Ultra spectrometer. XRD measurements were carried out with a Bragg/Brentano diffractometer (X pertPro Panalytical) equipped with a fast X Celerator detector Au particle size values were calculated by the Scherrer equation. Prepared catalysts and some characterization data are reported in Table 1. 

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