Synthesis, Structures and Magnetic Properties of the New Vanadates AgMnVO4 and RbMnVO4.

The new compounds, AgMnVO{sub 4} and RbMnVO{sub 4} have been synthesized by solid state reaction route. Their crystal structures were determined from single-crystal X-ray diffraction data for RbMnVO{sub 4} and powder X-ray diffraction data for AgMnVO{sub 4}. AgMnVO{sub 4} crystallizes with the maricite-type structure in space group Pnma, a=9.5778(6) A, b=6.8518(4) A, c=5.3734(3) A and Z=4. RbMnVO{sub 4} crystallizes in space group P6{sub 3} with a stuffed tridymite-type structure, a=11.2584(3), c=8.9893(13) A and Z=8. A merohedral twinning was taken into account for its structural refinement. To our knowledge this is the first vanadate showing this structural type. AgMnVO{sub 4} and RbMnVO{sub 4} were characterized by magnetic susceptibility and specific heat measurements. AgMnVO{sub 4} is antiferromagnetic with a Neel temperature of 12.3 K determined by specific heat measurements. RbMnVO{sub 4} exhibits canted antiferromagnetism with a Neel temperature of 6.5 K. - Graphical Abstract: The new vanadates AgMnVO{sub 4} and RbMnVO{sub 4} have been synthesized by solid state reaction. They crystallize with a maricite-type and a stuffed tridymite-type structure, respectively. Antiferromagnetic interactions were observed in both compounds.