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BGMN Application: Standard Sample Kaolin Spergau

Author:

Dr. R. Kleeberg

Sample preparation:

• 8 min McCrone milled in ethanole
• side-loaded into the holder for minimization of preferred orientation
• sample diameter 27 mm, thickness 1.5 mm

Measurement:

• XRD 3000TT, Cu long fine focus tube;
• automatic divergency slit, irradiated sample length 10mm
• secondary graphite monochromator
• angular range 5°...70°, 0.02° step size

Calculation:

• correction for tube tails
• global parameters: zero shift, sample displacement
• background manually set to 4 parameters. This was proved to be useful for the clay disorder model.
• phase specific parameters: see table 1
• whole number of parameters: 85

Table 1: Phase parameters for calculation

Phase	Lattice parameter count	Prefered orientation	Peak shape model	Special features
quartz	2	4th order	crystallite size	-
kaolinite	6	2th order	clay disorder model	-
muscovite 2M1	4	2th order	crystallite size and micro strain	site occupation for K+
Illite 1Mt	4	-	crystallite size and micro strain	-
svanbergite	2	4th oder, automatic reduced to 2th order	crystallite size and micro strain	-
anatase	2	-	crystallite size	-

Results: (recalculated using BGMNwin on December 2005)

R_wp = 8.6 %; calculation time: 7 min;

Table 2: Calculation results (weight %)

Phase	Nominal content	Rietveld content
quartz	15.0	16.2
kaolinite	71.6	71.6
muscovite 2M1	12.8 (illite)	muscovite 2M1 9.0 Illite1Mt 0.9 =9.9
accessories	-	Svanbergite 1.0 Anatase 0.7 =1.7

Figure 1: Observed, calculated and difference pattern for the kaolin Spergau sample