Abstract

The crystal structure of Ba4Ru3O10 has been determined by single-crystal x-ray diffraction at room pressure. F refinements to R-0.0203 at room temperature and ambient pressure, the material is orthorhombic with space group Cmca (S-ace group no. 64) and has lattice parameters of a=5.7762 (15)Å, b=13.271 (4)Å, and c=13.083 (3)Å. The unit cell thus has a volume of V=1002.9(8)Å3 and contains four formula units (Z=4). Ba4Ru3O10 is therefore of higher symmetry than the previously reported monoclinic structure based on powder x-ray data. It is isostructural with the quaternary oxides Ba4(Ti,Pt)3O10 and Ba4Ir2AlO10 and the ternay fluorides Cs=4M3F10 (M=Mg, Co, Ni, Zn). Kinked chains of RuO6 octahedra run along the c direction, consisting of sets of three face-sharing units joined at the corners of the end-units to additional similar sets. The two distinct Ba sites show 10-fold and 11-fold coordination.

Compressibilities and bulk modulus have been determined from lattice parameter variations at pressures up to 5.4 GPa. No phase transition was upserved up to this pressure. Compressibility is greatest along the c axis and the bulk modulus from a weighted fit to a Vinte equation of state is 113.3(47) GPa.