Synthesis crystal structure and ionic conductivity of Ca_0.5Bi₃V₂O₁₀ and Sr_0.5Bi₃V₂O₁₀

Abstract

Two new compounds Ca_0.5Bi₃V₂O₁₀ and Sr_0.5Bi₃V₂O₁₀ have been synthesized in the ternary system: MO-Bi₂O₃-V₂O₅ system (M=M²⁺). The crystal structure of Sr_0.5Bi₃V₂O₁₀ has been determined from single crystal X-ray diffraction data, space group P1^- and Z=2, with cell parameters a=7.1453(3) Å, b=7.8921(3) Å, c=9.3297(3) Å, α =106.444(2)°, β =94.088(2)°, γ =112.445(2)°, V=456.72(4) ų. Ca_0.5Bi₃V₂O₁₀ is isostructural with Sr_0.5Bi₃V₂O₁₀, with, a=7.0810(2) Å, b=7.8447(2) Å, c=9.3607(2) Å, α =106.202(1)°, β =94.572(1)°, γ =112.659(1)°, V=450.38(2) ų and its structure has been refined by Rietveld method using powder X-ray data. The crystal structure consists of infinite chains of (Bi²O²) along c-axis formed by linkage of BiO₈ and BiO₆ polyhedra interconnected by MO₈ polyhedra forming 2D layers in ac plane. The vanadate tetrahedra are sandwiched between these layers. Conductivity measurements give a maximum conductivity value of 4.54×10^-5 and 3.63×10^-5 S cm^-1 for Ca_0.5Bi₃V₂O₁₀ and Sr_0.5Bi₃V₂O₁₀, respectively at 725 °C.