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Microsoft Word - Matl 413 and MATL 913 X Information for XRD Prac Write Up : David Wexler Information for XRD Prac Write Up : David Wexler Information for Diffraction Report No 2 Write Up David Wexler...

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Microsoft Word - Matl 413 and MATL 913 X
Information for XRD Prac Write Up : David Wexler

Information for XRD Prac Write Up : David Wexler

Information for Diffraction Report No 2 Write Up David Wexler

X-ray Diffraction Report No. 2 Write-up instructions
Report is due via Turnitin on Wed. 10th June, 10:00 pm, Worth 20%
Note: The answers in this report need to be in your own words. Significant marks will be deducted from your report if identical wording is used for reports produced by different people. As in XRD Report 1, remember to use and cite references (MARKS will be lost for poor referencing). Extra marks will be given for evidence of deep thinking and/or understanding.
Part A Understanding a Search of the Database which gives a range of possible results (8 Marks)
Figure 1 Shows XRD processed data obtained from a mixture of 2-Powders; BCC Tantalum (Ta) and Face Centred Cubic Praseodynium Oxide (PrO2). The results were obtained using our Bragg-Brentano diffractometer Traces Software and the ICDD Search-Match Database PC-PDF2. Some of the data processing steps are shown in the Figure. A search-match was performed using a search window of 0.2 degrees and using tie ICCD-PC-PDF database database from all the elements marked yellow in the periodic table. A tabulated output of the search-match is also shown in the Figure.


Tabulated Output .. The top 5 Search-match results in order of merit:
Match    PDFCard No.    Phase Name (Chemistry)        Merit    Ic/Io    Peaks Matched Structure
1/50     XXXXXXXXXX    NIOBIUM VANADIUM HYDRIDE/Nb0.498 V0.50H 1.00         3/3     Im-3m    
2/50     XXXXXXXXXX    TANTALUM/Ta      1.00         3/3     Im-3m
3/50     XXXXXXXXXX    NIOBIUM/Nb      1.00         2/2     Im-3m
4/50     XXXXXXXXXX    NIOBIUM/Nb      1.00         3/3     Im-3m
5/50     XXXXXXXXXX    PRASEODYMIUM OXIDE/Pr O2 XXXXXXXXXX0.41         5/5    Fm-3m     
Figure 1 XRD Output an Search Match Results performed on a mixture of two powders, Ta and PrO2
Part A Continued.
As can be seen from the analysis in Fig. 1, Ta was listed only as the 2nd best match, and PrO2 as the 5th best match, even though Ta and PrO2 are actually the only phases present in the sample. Other structures included a database card matching a hydride phase of Nb and V, and two separate database cards matching pure Nb.
Part A Questions:
i Briefly explain what information is revealed in the six XRD spectra in Fig. 1 (e.g., You may need to zoom in the view in order to see some results in more detail).              XXXXXXXXXX2 Marks
ii Explain why Pure Niobium was appears as a possible match, with pedicted peaks very close to those of Ta.                                              XXXXXXXXXXMarks
iii Explain why a coupound of Nb and V, which also contains interstitial hydrogen might have the same crystal structure as Ta.                                     XXXXXXXXXXMark
iv PrO2 has the space group Fm-3m. What is the common name for this type of cubic structure?                                                      XXXXXXXXXXMark
v Go to the Crystallography Open database http:
www.crystallography.net/cod/ and perform a search for structures containing both Pr and O. You should be able to locate .cif files of the phase O2Pr, having space group Fm-3m. Wright down the COD ID for one of these .cif files and write down the lattice parameter.                                         XXXXXXXXXXMarks
Part B Interpreting Diffraction Outputs after Milling a Mixture of Inorganic Powders (7 Marks)
Figure 2 shows are XRD outputs from a mixture of Copper Powder, Aluminium Oxide (Al2O, also called Corundum) and Ca
on (in the form of Graphite). The blue (upper) XRD output is from the undeformed sample. The sample was made by gentle mixing of the three powder ingredients. The lower XRD output (Red) is taken form the same sample after ball milling of the powder mixture for 60 hours (by tumbling the powder in a round chamber with heavy steel balls). The milling was done in the ball mill to pulverise the powder mixture, introduce severe deformation, and to reduce the crystallite sizes.

Milled
powde
Unmilled
powde
Peaks used for crystallite size estimates
Figure 2. XRD Outputs from as-received powder mixture (Blue) and mixture after ball milling for 60 hours (Red) in a controlled atmosphere ball mill.
You will notice that both the Corundum peaks (Green Peak Position Markers) and Copper peaks (Brown Position Markers) have
oadened and changed shape and height after milling. This is due to a combination of refinement of the crystallite size and, for the case of Copper, introduced defects. The graphite (Ca
on XXXXXXXXXXpeak at around 26.6 degrees (Matching the Orange marker) has disappeared after milling.
Part B Questions
i. Explain what might be the likely reasons that the Graphite Peak (Orange marker) has disappeared. To answer this you need to think about what might happen to the mix of powders, as the particles are compacted, sheared and
oken up by the action of the balls striking and shearing the powder particles. Then think about what this might do to the diffraction peaks associated with the different powder particles in the mill.                             XXXXXXXXXX3 Marks)

ii. Using the Sche
er formula (Given in Fig. 3, and also described in your XRD lecture notes) calculate both the Copper and the Corundum crystallite sizes after milling, based on the information given below. Give reasons why the results for copper and Corundum differ (there is more than one possible reason).                             XXXXXXXXXX Marks)
Figure 3 Example of estimate of FWHM Peaks using Traces Software (Peak Positions were identified after Kstripping and smoothing)
Peak                    Angle at peak    FWHM
Copper Pk before Milling        50.45            0.26
Copper Pk after Milling 60 Hrs    50.35            0.99
Al2O3 Pk before Milling        57.51            0.19
Al2O3 Pk after Milling for 60 hrs    57.70            1.49
Part C Residual Stress and Interpreting combined XRD and SEM Results XXXXXXXXXXMarks)
(i) Describe in simple terms how an XRD instrument can be used to perform a residual stress analysis of a strained steel sample. What needs to be measured, and how are the measurements performed.                                          XXXXXXXXXXMarks)
(ii) Below are XRD outputs and SEM EDS Maps of a sintered mixture of Nitrided Ti and Fe. Explain how these XRD results were combined with the SEM-EDS mapping results to determine the phases indicated on the fracture surface (Bottom SEM Backscattered Image).                                                 XXXXXXXXXXMarks)

Figure 4 XRD, EDS Maps and SEM Fracture Surface of a sample of Nitrided Titanium, Liquid Phase Sintered in an Fe-Ti containing liquid.
Answered Same Day Jun 09, 2021 MATL913

Solution

Rahul answered on Jun 10 2021
134 Votes
X-Ray Diffraction
Part A
X-ray powder diffraction (XRD) is a rapid analytical technique primarily used for phase identification of a crystalline material and can provide information on unit cell dimensions. The analyzed material is finely ground, homogenized, and average bulk composition is determined. In this report, by using these techniques we try to identify the crystalline structure through XRD. The data of mixture of two powder is used. BCC Tantalum (Ta) and FCC Praseodynium Oxide (PrO2). The X-ray diffraction method is used to identify the crystalline structure.
1. The six spectra in the Figure 1 has following paramete
    Peak Numbe
    2-theta angle
    Raw intensity
    d spacing
    Relative Intensity
    6
    37.16
    60
    2.417
    7

The powder is mixture of BCC Tantalum (Ta) and FCC Praseodynium Oxide (PrO2). Ideally there should be two phases are involved one is tantalum(Ta) and Praseodynium Oxide (PrO2).
Dot Shows Peaks
But Due to contamination there may be mixing of other material phases due to some unavoidable reason. In the next figure we can see how many other materials are present in the mixture.

At six spectra phase matches with Praseodynium Oxide (PrO2). In this figure the six spectra revels the information about the Praseodynium Oxide powder only.
2. During the X-ray diffraction, when Database power Diffraction file (PDF) is used to contain a list of all the crystalline phases.
Reasons for variations in peak intensities of XRD powder patterns in compare to the PDF file is following are
a. Grain size
. Particle size,
c. Crystallite size - Coherently Diffracting Domain (CDD) Size
d. Data normalization method
e. Peak intensity versus integrated intensity
f. Geometry and XRD optics used including incident beam conditioning and slits used.
    But in this case there is one clue which comes under the observation is that Ta and Nb
Place in same column in periodic table. So there is reason of the same Crystallite size may be reason that there are both shows same. There is also one reason that can occur is that PDF mainly compare the relative intensity. So in this case due to mixture of the powders relative intensity of the Ta becomes equal to the relative intensity of Nb in the file.
3. The compound of Nb and V, which also contains interstitial hydrogen might have the same crystal structure as Ta. The reason behind this is that Nb,V and Ta are in same column in the periodic table. The difference between them is different atomic number. The difference between the number of electrons. In X- ray diffraction a
angement of electron can act as slit for the experiment and effect the pattern of diffraction which directly proportional to the intensity. There is a possibility the combination of Na, V and hydrogen make the same electron a
angement like as Ta and there is known fact that Ta has more atomic number. In the X-ray...
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