(2 1 1) > (3 0 0) > (3 1 1) > (2 2 2) 3
Procedure It is assumed that the unknown powder sample is homogeneous in composition, crystalline in structure, and randomly oriented. Different sample holders may be required for different specimen volumes (e.g. if you only have a small amount of sample). Two different specimen volumes were extracted from the unknown sample, prepared in different sample holders, and scanned in an X'Pert PRO Alpha-1 diffractometer. Each student will be given a unique set of parameters to test the unknown sample with. In your own words, briefly describe the sample preparation procedure. After acquiring a well-mixed sample of powder and the sample holder was cleaned of residue, the powder was poured into the sample holder. The sample is then packed using a flat tool, such as a blade, to flatten the mound of the sample and remove any excess of the sample. The sample is packed to about 70% to ensure limited bubbling within the sample. The sample is then wiped down and is ready to be analyzed by XRD. Provide the instrument parameters used for data collection on the sample you prepared below Sample Name: Cu Monochromatic x-ray source: kα 1 with wavelength 1.541Å. X-ray tube operating settings: 45 kV, 40 mA Start 2 θ: 20 o End 2 θ: 100 o Incident Soller Slit: 0.04 radians Mask Size: 10mm Incident Divergence Slit: 0.25 o Incident Anti-scatter Slit: 5 o Diffracted Soller Slit: 0.04 radians Diffracted Anti-scatter Slit: 0.04 radians Detector: X’Celerator Name the two types of sample holders used in this lab. What is the primary reason for choosing one sample holder over the other? What affect does sample volume have on the diffracted beam intensity? The two types of sample holders used in this lab are regular sample holders and zero-background sample holders. The primary reason for choosing one sample holder over the other is simply how much sample we have. The zero-background sample holder is made of a material that absorbs the x-rays that go through the sample powder and thus gives us zero-background noise. The larger the diameter of sample holder we use, the better the resolution of our data due to the large area of sample exposed to the x-ray beams. 4
Results Insert a plot showing the diffraction pattern generated with your instrument settings. Normalize the intensity in your plot such that the most intense peak has an intensity of “100.0” and all other intensities are relative to this value. Use the provided label below with your sample name inserted in the blank space. Figure 2: Diffraction Profile for Sample Cu. Position [°2θ] (Copper (Cu)) 30 40 50 60 70 80 90 Counts 0 200 400 600 mse2021wednesday_3 List each peak observed in the Table 1. In the space below, show your work for the conversion of the observed 2 value to the corresponding value of d-spacing. State any assumptions needed for this calculation.
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