Phase separation in NaTaO3. Impact of temperature and doping

•Phase separation in NaTaO3 studied using high resolution powder diffraction.•At room temperature Pbnm and Cmcm phase co-exist in polycrystalline NaTaO3 samples.•Annealing has little impact on the phase distribution at room temperature.•Doping has a significant impact on phase separation, tending to favour the Cmcm phase.

The importance of sample history on the Pbnm-Cmcm phase coexistence in NaTaO3 has been investigated using high resolution neutron and synchrotron X-ray diffraction methods. These results reveal that the phase coexistence, associated with the first order Pbnm-Cmcm phase transition, is not significantly affected by the annealing conditions used to prepare the sample. Rather it is found that compositional inhomogeneities or defects play a significant role in stabilising the high temperature Cmcm phase at room temperature.

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