Crystal structure of the alluaudite Ag₂Mn₃(VO₄)₃

The new compound Ag₂Mn₃(VO4)₃ was synthesized by hydrothermal and solid state reaction routes, and its crystal structure was determined from single-crystal X-ray diffraction data. Ag₂Mn₃(VO4)₃ crystallizes with a monoclinic symmetry, space group C2/c, with a=11.8968(11) Aa, b=13.2057(13) Aa, c=6.8132(7) Aa, β=111.3166(15) ( ) and V=997.16(17) Aa³ (Z=4). Its crystal refinement yielded the residual factors R(F)=0.0249 and wR(F²)=0.0704 for 95 parameters and 1029 independent reflections at a 3σ(I) level. Ag₂Mn₃(VO4)₃ can be considered as a new member of the AA^'MM^'₂(XO4)₃ alluaudite family. The specific arrangement of M and M^' octahedral sites and of X tetrahedral sites gives rise to two different channels aligned along the crystallographic c-axis and containing the A and A^' sites. The A, A^', M, and X sites are fully occupied by Ag⁺, Mn²⁺, and V⁵⁺, respectively; whereas a Mn²⁺/Mn³⁺ mixture is observed in the M^' site.