Grain mapping of a complex perovskite transition

ABO3 perovskites are an important class of functional materials. Cation ordering at A or B sites gives an AA’B2O6 or A2BB’O6 double perovskite (DPv) and 1:1 cation ordering at both sites can give an AA’BB’O6 double double perovskite (DDPv). CaMnMnWO6 undergoes a first order transition from a fully-ordered DDPv form to the A-site disordered DPv polymorph (Ca0.5Mn0.5)2MnWO6 at 1260 ⁰C under 10 GPa synthesis pressure. A 3DXRD grain mapping experiment on a ceramic pellet recovered from just below the transition that has approximately equal amounts of the DDPv and DPv phases is proposed. This will explore microstructural changes at the transition such as relations between domains and cell axis directions of the DDPv and DPv phases, and residual lattice strains within the ceramic sample after high-P,T treatment. The hard X-rays and high resolution of ID11 will be needed to distinguish between the very similar cell parameters of the DDPv and DPv phases within the bulk pellet.