What do we need from the data?
Accurate Unit Cell volumes to obtain the “equations of state” of the phases of interest (how the volume of the phases change with pressure and temperature)
T - RbClO4 = B2-RbCl + 2O2
4 R-KClO3 = 3 O-KClO4 + B2-KCl
O2 from the differences in the unit cell volumes
Thus use powder diffraction