Crystal structure and ionic conductivity of ruthenium diphosphate ARu2(P2O7)2, A=Li, Na, and Ag, with a tunnel structure

Crystal structure and ionic conductivity of ruthenium diphosphates, ARu2(P2O7)2 A=Li, Na, and Ag, were investigated. The structure of the Ag compound was determined by single crystal X-ray diffraction techniques. It crystallized in the triclinic space group P−1 with a=4.759(2) Å, b=6.843(2) Å, c=8.063(1) Å, α=90.44(2)°, β=92.80(2)°, γ=104.88(2)°, V=253.4(1) Å3. The host structure of it was composed of RuO6 and P2O7 groups and formed tunnels running along the a-axis, in which Ag+ ions were situated. The ionic conductivities have been measured on pellets of the polycrystalline powders. The Li and Ag compounds showed the conductivities of 1.0×10−4 and 3.5×10−5 S cm−1 at 150 °C, respectively. Magnetic susceptibility measurement of the Ag compound showed that it did not obey the Curie–Weiss law and the effective magnetic moment decreased as temperature decreased due to the large spin–orbital coupling effect of Ru4+ ions.