Neutron powder diffraction and difference maximum entropy method analysis of protium- and deuterium-dissolved BaSn0.5In0.5O2.75+α

We propose a new method, a difference maximum entropy method (MEM) analysis of the neutron diffraction data, for revealing the detailed structure around hydrogen atoms in proton-conducting oxides. This MEM analysis uses the differences between the structure factors of protium- and deuterium-dissolved crystals. Simulations demonstrate that it not only provides the distribution of hydrogen atoms alone, but also improves the spatial resolution of MEM mapping around hydrogen atoms. Applied to actual diffraction data of protium- and deuterium-dissolved BaSn0.5In0.5O2.75+α at 9 K, difference MEM analysis reveals that O–D bonds mostly tilt towards the second nearest oxygen atoms, and that the distributions of deuterium and oxygen atoms are probably insignificant in interstitial regions.