Fig. 4. Goodness-of-fit parameters (R w) as a function of r-max for 10 Å incremental fits of the X-ray PDF data at 360 K against the various space group models for (a) MASnI3, (b) FASnI3, (c) MAPbI3, and (d) FAPbI3. Models that allow B-site displacements (I4cm and R3m) have lower R w values with an r-max of 5 Å for all samples, while cubic Pm3m results in lower R w values for all fits with an r-max of 10 Å and above.
