1. In JADE software, what is the principle of Tufeng extension selection when making full spectrum fitting of metal oxide powder? When do I choose a separate half-width curve? Under what circumstances do you choose to fit grain size and strain?

Answer: Depending on the needs of the analysis, choose the appropriate option, if you are concerned about grain size and strain, then select "fit grain size and strain". It should be pointed out that when analyzing data in JADE, if "fitting grain size and strain" is selected, a standard instrument curve needs to be established. On the established instrument curve, the grain size and strain can be accurately calculated by means of convolution. If the grain size exceeds 500A, it should not be particularly accurate. If you choose to "fit a single half-height width curve", you usually need to have three parameters f0,f1 and f2 (half-height width =f0+f1*2θ+f2*2θ^2) to fit a half-height width curve from low Angle to high Angle, usually the half-height width curve is a parabola with an opening upward, normal diffractometer, low-angle half-height width is higher, and the middle Angle is low. The advantage is that the parameters are few. When multiple phases are refined at the same time and the peak width is too wide due to the overlap of diffraction peaks, the intensity of some diffraction peaks disappears in the background medium condition, and the parameters of "fitting a single half-height and width curve" are few, which can be well fitted.

2. Do we need to consider the RIR value when using DD method for quantitative analysis?

Answer: No, DD method quantitative analysis, completely rely on the chemical formula to carry out quantitative analysis. When using the DD method to do quantitative analysis, in order to ensure a high accuracy, the following points should be noted:

(1) The range of the XRD pattern should be as large as possible to collect as many diffraction peaks as possible;

(2) The difference in cell volume between each phase should not be too large;

(3) The ordinal number difference between the various phases should not be too large;

For example, the number of diffraction peaks of phases with high symmetry and small cell volume is less than 90°, the number of diffraction peaks of phases with low symmetry and large cell volume is more than 90°, and the percentage of the total diffraction capacity of different phases is different within a certain range, then the accuracy of quantitative analysis using the DD method will be reduced. In addition, due to the influence of temperature factor, the difference in atomic number leads to the difference in the scattering ability of atoms to X-rays, and the difference in attenuation ability of heavy atoms and light atoms to X-rays at different angles will also affect the accuracy of quantitative analysis by DD method.

3. When multiple WPF fits, the results are quite different. Why?

Answer: If multiple fitting, if the difference in R-value or the difference in the relative content of phase is large after fitting, the possible reasons are: (1) the phase selection is wrong; (2) When finishing, the parameters of finishing are too few or too many, and some finishing parameters are interrelated; JADE has a more useful function, common >> EPS&CC to show the correlation degree between the various parameters of finishing. For some parameters with strong correlation, it may have little impact on the R-value of the overall finishing, but it has a great impact on the analysis result of the weight ratio. The process of finishing is mainly the process of reducing the difference map. If there is a serious overlap of diffraction peaks, modifying some finishing parameters will have a small effect on the finishing difference map, but may have a larger effect on other analytical results such as the weight ratio.

4. What is the relationship between PDF card number and CCDC number? How to find the CCDC number by the PDF card number, or find the PDF card number by the CCDC number?

Answer: The PDF-4 Organic database contains the single crystal structure data of CCDC. The PDF card number starts with 02, and the source of the structural data is the CCDC database, but the PDF card number has no correlation with the CCDC number. Currently, PDF cards can be stored in the PDF card database by means of chemical formula, compound name, etc. The PDF card also contains the corresponding CCDC number.

5. How to import specific PDF card data in the phase retrieval process?

Answer: In the process of phase retrieval, JADE supports the import of specific PDF card data according to the PDF card number, phase name, mineral family, etc. This function can be realized in the "phase search toolbar" in the phase retrieval module.