Hello Everybody, I am from the University Duisburg-Essen (Germany) and am responsible for XRD measurements/evaluation in our group. We use an X’Pert Pro MPD from Panalytical with a PW3050/60 Goniometer and Cu K alpha radiation. Our XRD is capable of measurements using powder and grazing incidence (GI) configuration. Using the grazing incidence configuration for our samples, we detect a “step” in our XRD patterns, but only for the elements Fe, Co and Mn (cause fluorescence). I call it step, because we are detecting a sudden decrease or increase of intensity. First of all, I would like to give you some more details about the setup and the preparations of our samples.
For the GI configuration we us a Göbel Mirror (Cu W/Si) as parallel beam optics. The width of the beam is determined by a fixed Mask (usually 10mm) and a fixed divergence slit (usually ¼°). The Sample is placed on a <911> Silicon Zerobackground Holder, which is placed in the middle of the stage. A proportional detector (PW3011/20) measures the diffracted beam. The module contains a 0.18° Parallel plate collimator. During the measurements the soller slit and receiving slit are not used to assure the maximum intensity is measured. During the adjustment of the sample, we calculate the 2Theta-Offset of the Goniometer and position the detector parallel to the cathode. Afterwards we adjust the cathode position to assure a parallel position of the sample towards the incident beam. I collect the data from 10°-100° 2Theta using a step size of 0.025° and a time per step of 1s. The samples are prepared from highly concentrated dispersion of nanoparticles and are dropped multiple times on <110> Silicon wafers (10mm x 10mm x 525µm). To speed up the drying process we place the sample on a 50°C hot heating plate inside the fume hood. Due to the multiple dropping we can guarantee an amount of 1-2.5mg of material. 2.5mg are needed for producing good quality patterns of Fe, Co and Mn. The result of the fast drying process is a very heterogeneous film on the substrate visible by the eye. 1st Pattern: https://1drv.ms/i/s!AqySCC4FBB1Ggegza_C-FlRL9EEwBA 2nd Pattern: https://1drv.ms/i/s!AqySCC4FBB1GgeUDBEczz0KqLTtyOA The first XRD Pattern is α-Fe2O3 [R -3 c H(167)] from Sigma Aldrich to see how the “step” reacts to different grazing angles. I varied the grazing from 0.25° until 2.00° in different steps as you can see in the picture. The other XRD Patterns are two different Ni-Mn Samples prepared following the exact same procedure. The peaks indicate the presents of Mn and MnO, but Ni which is due to the reaction. Does someone experience similar observations analyzing these elements using grazing incidence? Is there an explanation of the sudden increase and decrease of intensity at certain 2Theta-Angles? Kind regards, Thomas Winter P.S.: If you have issues with the links of my cloud, just let me know! Thank you very much in advance!
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