Maud全谱拟合精修定量教程.pdf
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1、 Maud 2.0 定量教程定量教程 宋党育宋党育 整理 河南理工大学 整理 河南理工大学 2007-6 Email: Tel:0391-3987976 QQ:48096753 Introduction Here are the instructions to perform a Rietveld quantitative analysis on a ZrO2/Al2O3 powder sample using Maud.Version 2.03(released September 12,2005)or higher is needed for this tutorial.The spect
2、rum for the analysis has been collected using a standard Bragg-Brentano diffractometer and the data file is located in the datasets and examples directory of Maud(the one created by you at the first run of the program).The procedure will start creating a basic analysis file setting up the datafile a
3、nd the two phases to analyze.We will build this analysis file in two steps:1)Step 1:load the datafile 2)Step 2:load and modify the phases Once defined the analysis file,we will start the analysis following two steps:3)Step 3:set up some visible parameters(specifically,the T-PSZ cell parameters)4)Ste
4、p 4:refine the spectrum by the wizard The final step(Step 5)will show the analysis output to the user.The tutorial will also guide the user to a more accurate and precise analysis if some parameters were not as expected.The tutorial has been added by several figures to help the novice in figuring ou
5、t easily the basic procedure to perform this kind of analysis.Step 1:load the datafile 1)Start the Maud program or,if you are already in,choose Newfrom the File menu to start a new analysis and reset all.2)Load the data file alzrc.dat from the Maud databases and examples directory(the one Maud asked
6、 for the first time you run it).3)There are three ways to do it.Choose only one.a)Locate the file in your system and drag and drop the file over the plot window of the principal Maud frame.When you are over with the file you should notice the plot panel border is highlighted.b)In the File menu choos
7、e Load datafile.,navigate to the file alzrc.dat and load it(Fig 1-1).c)(This third one is the usual when working with more datasets and datafiles,to get more control where to add and how many datafiles for each dataset to have)Select the Dataset_x with the mouse and press toolbar button similar to a
8、n eye(it says edit the selected object of the visible list when you go with the mouse over it).A new window will appear,select the Datafiles tab panel and press the Browse.button to load the datafile.Locate the alzrc.dat file in the databases and example directory and load it.Press the OK button to
9、close the dataset edit window at end.Fig 1-1 4)After loading the data file the main Maud window should look like this(you can drag the dividers between the four parts of the main panel to adjust their size as you prefer)(Fig 1-2):5)You may zoom in the spectrum plot in some details by click,old and d
10、rag the mouse over the window part you want to zoom in.Double clicking the plot reset the zoom to the normal.By right clicking on the plot(CTRL+click,if you have a one-button mouse)you have a small context menu for manual zooming or get a coordinate window.Pressing the Plot options button you gain c
11、ontrol over some plot characteristics.6)We do not need to modify the Instrument(inside the dataset)as the one loaded by default is a Bragg-Brentano with the correct instrumental aberrations for this data file.7)Before to proceed with Step 2(load and modify the phases)we save this analysis at the pre
12、sent state giving it a new name so we can load it again if needed.To complete this choose Save analysis as.and choose a location(better not inside the databases and examples directory)and a name for the file.It is adviced to use a name with extension.par so in certain system(MacOSX for example)can b
13、e recognized as a Maud analysis file and double clicking the file,it will be loaded automatically in Maud.Fig 1-2 Step 2:load and modify the phases 1)Select the Phases tabPanel in the main Maud window.2)There should be no phases in the list.If any,select it and press the remove button in the toolbar
14、(the one with a red cross).3)Press the Load an object from a(CIF)database or file.button to add a new phase(each button on the toolbar acts on the selected list and or object/s).Select the database file structures.mdb from the databases and examples folder.A window will appear where you can choose t
15、he corundum(Al2O3)phase first from the visible listbox(Fig 2-1).4)Repeat the procedure to add the phase T-PSZ from the same database.It is a the tetragonal zirconia Ce stabilized.Tip:you may load both phases from the database at once by selecting both.Discontinuous selection is permitted.On MacOSX y
16、ou can add more selections by holding down the Apple button and selecting whatever you need with the mouse click.On Windows and Lunix there is the same counterpart with their specific button-mouse click procedure.5)If you wish to check the phase characteristics for the corundum or T-PSZ you may sele
17、ct the specific phase and then click on the edit button on the toolbar(the eye icon button).6)A new window will appear with the phase crystallographic and microstructural characteristic and models.7)You dont need to do anything at the moment.At end close those windows with the OK button(Fig 2-2).Fig
18、 2-1 Fig 2-2 Step 3:set up some visible parameters;specifically,the T-PSZ cell parameters 1)We are now ready to check the starting parameters for the quantitative analysis.The main idea is to guide a little the starting analysis to ensure the least squares algorithm may find a solution.In general we
19、 should check that the phases we loaded are the correct one for the analysis and in particular that the peaks of the phases roughly correspond to peaks in the spectrum.2)First we compute the spectrum based on the actual parameters.To do this press the calculator toolbar button(the tooltip that it is
20、 shown when you leave the mouse few seconds over it says Compute spectra or from the Refinement menu,click on the Compute spectra menu item.The program will compute a spectrum with the actual values of the parameters,phases etc.and the spectrum plot panel will be automatically refreshed.You should h
21、ave at the end something like (Fig 3-1):Fig 3-1 The intensity is quite low and the computed spectrum in the high 2theta part does not correspond correctly to the experimental part(see between 140 and 150 degrees).3)Zoom in the plot panel in the 70-77 2theta degrees region by clicking and dragging a
22、rectangle around the plot part you want to zoom in.You should see the two peaks of the tetragonal as in the next figure.The first peak(do not consider the small first one)correspond to the 004 reflection of the tetragonal PSZ,the second one to the 220.The calculated peaks are instead shifted towards
23、 high angle.This because the cell parameters depend strongly on the Ce content and the phase in the database has a different Ce content respect to the one in the experimental pattern.We will change the cell parameters to provide a better starting point(the calculated peaks actually are too far from
24、the experimental ones;the least square will diverge).4)Go to the lower panel containing a list(tree)of objects and parameters.Look for the cell parameters of the PSZ and click on the parameter value of cell parameter a.Like in the following figure(Fig 3-2).Fig 3-2 Near the value(inside the two arrow
25、 buttons)there is a step value.Change the value to 0.01 like in the picture.Clicking on the left or right arrow buttons you can decrease or increase the value of the parameter by the step value.The change in the value will be followed by a quick computation and update of the plot to reflect the chan
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