Suggested workflow

PeakPo provides tools to conduct phase identification, peak assignments, and unit-cell fitting. They are distributed over different taps in PeakPo. However, you can maximize their capabilities by following the workflow below.

Step 1. JCPDS tweak

Try to achieve the best alignment between the expected peak positions from JCPDS and your observed lines by tweaking the b/a, c/a, and V0 in the JCPDS2 tab. If your JCPDS bars and the observed peak positions are within 0.3 degrees, you did good job. This is the most critical step for the successful unit-cell fitting in PeakPo.

Step 2. Peak fitting

Once you have good tweaks, the information can be carried over to peak fitting. As you will see, you can use the tweaked peak positions as starting values for peak fitting. Additional benefit here is that Miller indices will be also stored during peak fitting. This will be ultimately transferred to unit-cell fitting. I strongly recommend to divide a pattern into 4-5 different angular ranges and then fit them separately as sections. Then the fitting results will be much better and the fitting will be much faster. The unit-cell fitting menu in PeakPo allow you to collect peak fitting results from different sections and then use them together for unit-cell fitting.

Step 3. Unit-cell fitting

Once you finish the two steps above, you can now provide complete information to unit-cell fitting function in PeakPo. In unit-cell fitting, you can decide which peaks to include or exclude. Also, you get advanced statistics of fitting. This information is particularly useful to identify error sources in unit-cell fitting.