Synthesis and crystal structure of LiCuFe2(VO4)3 by rietveld method

A new triple vanadate LiCuFe2(VO4)3 was synthesized by a solid-state method. The compound is isotypic with mineral howardevansite, NaCuFe2(VO4)3, and crystallizes in a triclinic system (space group P1̄ (No. 2); a = 8.1484(5), b = 9.8024(7), c = 6.6355(4) Å, α = 103.832(3), β = 102.353(3), γ = 106.975(3), V = 468.68 Å3, Z = 2). Crystal structure of LiCuFe2(VO4)3 was refined by Rietveld method with RWP = 2.32%, RP = 1.76%, RI = 2.82%, S = 1.55, using X-ray diffraction. The crystal structure has five independent cation sites. Lithium cations are located in the cavities M(1)O6 and M(5)O10, which form infinite chains in the [001] direction and are linked through a common face. The lithium cation in the M(1)O6 cavity has a square planar coordination. The lithium cation in the M(5)O10 cavity is strongly displaced up to 1.2 Å from the special position (0, 0, 0.5) to a half-occupied general position (0.037, 0.087, 0.40).