ABSTRACT:Hydrogen titanium oxide H2 Ti3O7was prepared from
Na2 Ti3O7 as a parent compound via Na+/H+
ion exchange in acidic solution at 333 K. It crystallizes in the monoclinic system, space groupC2/m, and the lattice parameters of a= 16.0380(8) Å,b=
3.7533(1) Å,c = 9.1982(3) Å, andβ= 101.414(3)°. The crystal structure of H
2Ti3O7was refined to the conventional values ofRwp=
2.60% andRp = 1.97% with afit indicator of GOF =Rwp/Re= 1.90 by
Rietveld analysis using powder neutron diffraction data. The basic (Ti 3O7)2−
framework in H2 Ti3O7 was changed from that in the parent Na2 Ti3O7. The atomic coordinate of hydrogen atoms were determined by this study for thefirst time. The hydrogen site in the layer space was refined with a strict H1−O3 distance of 0.80(2) Å and H2−O4 distance of 0.86(2) Å in H2 Ti3O7,respectively. The structural stability of H2 Ti3O7was confirmed by bond valence sums. From these results, protons were suggested as the ordered occupation in the crystal structure