Synthesis, crystal structure and lithium ion conduction of Li_3BP_2O_8

摘要

Single crystals of Li_3BP_2O_8 were prepared by heating a mixture of starting materials with a Li:B:P molar ratio of 22:11:13 at 933 K in air and by cooling at a rate of -10 K h~(-1). The X-ray diffraction (XRD) reflections of a single crystal were indexed with triclinic cell parameters: a = 5.1888(5) ?, b = 7.4118(7) ?, c = 7.6735(7) ?, α = 101.18(1)°, β = 105.07(1)°, γ = 90.34(1)° (space group P1 (no. 2)). In the crystal structure of Li_3BP_2O_8, BO_4 and PO_4 tetrahedra share O atoms and form one-dimensional _∞ ~1[BP_2O_8]~(3-) chains along the c-axis direction. A polycrystalline Li_3BP_2O_8 bulk sample was synthesized by the solid state reaction of Li_4P_2O_7 and LiPO_3 prepared from the starting materials in advance with H_3BO_3 at 923 K. The lithium ion conductivities measured for the polycrystalline sample by the AC impedance and DC methods were 1.5 × 10~(-5) S cm~(-1) at 583 K and 6.0 × 10~(-8) S cm~(-1) at 423 K, respectively.