Quantitative

Quantitative Refinement

Aim of problem: This problem shows how one can obtain quantitative analysis of a paracetamol/lactose two phase mixture. The aim is not to get the best structural fit but to obtain the most reliable scale factors for each phase, from which the composition may be obtained. The data were collected using a capillary sample on Stoe laboratory diffractometer with Cu Ka1 radiation ( =1.54056Å).
Data are in paracetamol-q.gsas, coordinates for the two structures in paracetamol_coord.txt and lactose_coord.txt. You can use stoe.inst to describe the diffractometer.

Instructions
1. Set up the Rietveld .exp as normal.

2. Coordinates can be read in using the dos version of expedt. In least squares/atoms menu use option “i r” to read coordinates from the text files. The program will ask which columns of the file contain the atom name, type, x, y and z.

Outcome
Accurate phase percentages!