Franklin & Marshall College Franklin & Marshall College

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X-ray Diffraction

  The PANalytical X'pert Pro x-ray diffractometer is used by students and faculty in the Departments  of Earth and Environment, Chemistry and Physics.  Examples of student and faculty XRD research  include identification of minerals in rocks, soils and lake sediments, characterizing nanoparticles and the properties of synthetic double chain salts.

 X-Ray Diffraction Instructions for Routine Identification of Crystalline Materials

 Warning:  The X-ray diffractometer produces a primary X-ray beam that can cause serious injury.  Students must complete training before using the XRD. Your name must appear on the list of approved users on the front of the instrument.

 These instructions are for the routine identification of crystalline materials found in the International Center for Diffraction Data database. The XRD uses an automatic sample changer to load and unload samples. It can hold up to 15 samples. These instructions assume samples are mounted on glass slides and held in the 32 mm samples holders.

 Sample holders may not be taken form the lab and must be emptied when finished. Please do not leave samples or glass slides in the lab and be sure to clean up after you are finished. Log off the X-ray software when finished.

 Loading Samples into the XRD

 1.     Check and make sure the XRD is not currently running samples. On the front panel of the XRD the MA should read 20, the KV 40 when the unit is not in use.

2.     Slide open both XRD doors.

3.     The sample holder positions are 1-15, top to bottom. Place samples in position as per your list.

4.     Never remove monitor sample from the bottom of sample changer.

5.     Close XRD doors. Do not slam door against each other.

 XRD Software

 Log on to the Computer – user name is XRD User and password is geochem.

 1      The desktop has three icons in the upper left corner. X-pert Data Collector activates the XRD and collects data.  X-pert High Score Plus performs a search match routine to help determine what the sample is.

 2      The XRD software has separate user and passwords for each department. User accounts exist for Physics User (pw= physics), Chem User (pw=chem) and Geo User pw= geochem.) Select the user account for your department.  Within each user folder are data folders established for faculty users. Student users may create personal data folders within faculty folders

 3      Open X-pert Collector

File

a. If you have already created a Sample (changer) batch program open under Open Program.  The Sample Changer Program is a generic batch  program that all are welcome to use. Or,  open New Program – select Sample (changer) batch from pull down menu – this opens pop up window – and create new program.

b. Make sure Stage Spinner Reflect/Trans. is selected

c. Go to new pop up window (4)

4      In Prepare Sample (changer) Batch File pop up window

a.      Insert

b.     Browse – Select Absolute Scan from pull down menu

c. Select Mineral ID 6-70deg. ADS for scan program

d. Click on file icon and select data file

e. Enter sample name and sample position in sample changer

f. When finished entering sample list, click on X-ray settings, check Set When Program is Finished, select Set, set MA to 20, KV to 40.

g. Close (using X in upper right corner) and save. You may name this batch program and save it for future use.

 

Click on Instrument – from pull down menu select Connect, then choose Select Stage Spinner Reflec/Transm – wait until connection process finishes. Anew pop up window X-pert Data Collector appears. If all triangles are yellow select OK. In view pane on left side of screen click on X-ray current – set x-rays to 40 MA and 45 KV

 

5      Click on Measure

Open Sample (changer) batch program and run.

When Finished – open doors and remove sample holder, empty samples and clean.

Identifying Samples

The following assumes your scan program used ADS – automated diffraction slit. Close or minimize X-pert Data Collector. From desktop icon in upper left open

X-pert High Score Plus

Select File – open your sample file

Search Peaks

   More

       Identify

                        Search peaks

 

Peaks have now been identified and indicate by arrows at the top of your scan, Check your scan to see if all peaks have been identifies.

If  yes, click Accept

X-pert High Score Plus       

                        Treatment – open entire list

Select Corrections, Convert divergence slit

 In new pop up box select ADS to FDS, and then Replace.

 

X-pert High Score Plus

(Background correction is not needed for some work.)

                        Treatment- Select Determine Background

                                    Subtract

                                                Replace

 The background is removed from your data and scan.

 X-pert High Score Plus

            Analysis

Search Match  - Execute Search Match

(In the search match dialog box you can chose to search the entire ICDD database by selecting default or a particular sub set of the data base (mineral, inorganic, etc,) by selecting restrictions

A chemistry filter is available in the edit function of S/M)

Select  None if you do not want to use a filter

            Search

                        OK

 

A list of “Candidates” for your unknown will appear on the right. The Candidates are ordered for most likely matches. A confidence “score” is given in the yellow column.  To further analyze the choices drag a high score candidate from the lower to upper pane. The number of candidates remaining in the lower pane will be reduced to reflect the subtraction of the candidate selected.

 

Click on peak list for a list of the peaks identified in your scan.  

Check for unmatched peaks.  Presence of large, unmatched peaks in your scan indicates other phases in your sample. If so return to the remaining Candidates list and drag additional phase candidates from the lower to upper pane.

X-pert High Score Plus

Report

Select Word

            Default

 

Drag report to right screen. Scroll down to list of measured peaks. On the left screen click on name of selected candidate. The ICD database card for that candidate will appear in a pop up box. Compare the known d-spacings and intensities in to pop up box to the measured d-spacings and intensities in the report on the right screen.

 

When Finished

Remove your samples from the sample changer

Remove slides from holders

Return sample holders to plastic box

Check that the XRD doors are close and that the MA is at 20, KV 40.

Log off the XRD software

Remove your slides and samples from the lab.