用OriginPro8求XRD pattern 的半高寬(FWHM)

1.     先用OriginPro8打開XRD pattern

2.     點選Analysis > Fitting > Fit Single Peak，進入NLFit視窗

P.S 如果已經有使用過此功能，Fit Single Peak之後要點選Open Dialog 才能進入NLFit視窗

3.     進入NLFit視窗後，點選Setting > Data Selection

4.     點選Range1  然後點選Select Range from Graph

5.     完成上述步驟後，圖形兩端會出現游標

6.     把游標移至要測peak的底部兩端

7.     游標移至完成後，按Select data in graph視窗右邊的圖示

回到NLFit視窗，點選Fit

8.     會跳出Reminder Message視窗，點選Yes，在按OK

9.     之後會出現一個table, 表格上就會顯示你選擇的peak的半高寬(FWHM)值

10.接著再帶入Scherrer equation計算particle size  (注意半高寬β要轉成弧度，即FWHM X π/180 = β)

where: 

τ is the mean size of the ordered (crystalline) domains, which may be smaller or equal to the grain size;

K is a dimensionless shape factor, with a value close to unity. The shape factor has a typical value of about 0.9, but varies with the actual shape of the crystallite;

λ is the X-ray wavelength;

β is the line broadening at half the maximum intensity (FWHM), after subtracting the instrumental line broadening, in radians. This quantity is also sometimes denoted as Δ(2θ);

θ is the Bragg angle.