Structure refinement of Rb4Mg3D10 on neutron powder diffraction data

Rb4Mg3D10 was synthesized by sintering stoichiometric mixtures of the binar y deuterides at 675 K and 100 bar D-2 for 5 days and characterized by X-ray and neutron powder diffraction. It crystallizes with the orthorhombic Cs2M g3F10 structure (space group Cmca (64), cell parameters a=6.0238(2) Angstro m, b=14.1126(5) Angstrom, c=13.4616(5) Angstrom, V=1144.4 Angstrom(3), Z=4) and contains two magnesium sites having distorted octahedral deuterium coo rdination and two rubidium sites having irregular 10-fold and 11-fold deute rium coordination. The metal-deuterium distances and shortest deuterium-deu terium distance (Rb-D: 2.82-3.38, Mg-D: 1.90-2.11, D-D: 2.59 Angstrom) are consistent with those found in the deuterides Rb2MgD4, Rb3MgD5 and RbMgD3. (C) 1999 Elsevier Science S.A. All rights reserved.