Structure of nano-crystalline FeTiD_x by neutron and X-ray diffraction

Complementary studies by neutron and X-ray diffraction were performed to elucidate the location of deuterium atoms in nano-crystalline FeTiD_x. Remarkable rearrangement of the metal atoms due to the deuterium absorption was observed in the pair distribution functions, g(r), obtained by X-ray diffraction. The result indicates that disordered grain boundary is developed through the deuterium absorption. The g(r) function obtained by neutron diffraction indicates the occurrence of two types of deuterium sites located inside the grains and in the grain boundaries, respectively. The deuterium atoms in the grain boundaries occupy tetrahedral sites consisting mainly of Ti atoms.