Synthesis and characterization of new fluoride-containing manganese vanadates A2Mn2V2O7F2 (A=Rb, Cs) and Mn2VO4F

• Published in: Journal of solid state chemistry 2016-09, Vol.241 (C), p.30-37
• Main Authors: Sanjeewa, Liurukara D., McGuire, Michael A., Smith Pellizzeri, Tiffany M., McMillen, Colin D., Ovidiu Garlea, V., Willett, Daniel, Chumanov, George, Kolis, Joseph W.
• Format: Article
• Language: English
• Subjects: Antiferromagnetism; Hydrothermal; INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; Manganese(II); MATERIALS SCIENCE; Vanadate
• ISSN: 0022-4596; 1095-726X
• DOI: 10.1016/j.jssc.2016.05.008

Large single crystals of A2Mn2V2O7F2 (A=Rb, Cs) and Mn2VO4F were grown using a high-temperature (~600°C) hydrothermal technique. Single crystal X-ray diffraction and powder X-ray diffraction were utilized to characterize the structures, which both possess MnO4F2 building blocks. The A2Mn2V2O7F2 series crystallizes as a new structure type in space group Pbcn (No. 60), Z=4 (Rb2Mn2V2O7F2: a=7.4389(17)Å, b=11.574(3)Å, c=10.914(2)Å; Cs2Mn2V2O7F2: a=7.5615(15)Å, b=11.745(2)Å, c=11.127(2)Å). The structure is composed of zigzag chains of edge-sharing MnO4F2 units running along the a-axis, and interconnected through V2O7 pyrovanadate groups. Temperature dependent magnetic susceptibility measurements on this interesting one-dimensional structural feature based on Mn2+ indicated that Cs2Mn2V2O7F2 is antiferromagnetic with a Neél temperature, TN=~3K and a Weiss constant, θ, of −11.7(1)K. Raman and infrared spectra were also analyzed to identify the fundamental V–O vibrational modes in Cs2Mn2V2O7F2. Mn2(VO4)F crystalizes in the monoclinic space group of C2/c (no. 15), Z=8 with unit cell parameters of a=13.559(2)Å, b=6.8036(7)Å, c=10.1408(13)Å and β=116.16(3)°. The structure is associated with those of triplite and wagnerite. Dynamic fluorine disorder gives rise to complex alternating chains of five-and six-coordinate Mn2+. These interpenetrating chains are additionally connected through isolated VO4 tetrahedra to form the condensed structure. New vanadate fluorides A2Mn2V2O7F2 (A=Rb, Cs) and Mn2(VO4)F have been synthesized hydrothermally. Upon cooling, the one-dimensional Mn(II) substructure results in antiferromagnetic ordering. [Display omitted] •Single crystals of A2Mn2V2O7F2, (A=Rb, Cs) and Mn2VO4F were grown hydrothermally.•The use of fluoride mineralizers in the synthesis led to the formation of new compounds without OH− groups.•The structure of A2Mn2V2O7F2 features zigzag chains of MnO4F2 units.•Cs2Mn2V2O7F2 exhibits antiferromagnetic ordering with a Neel temperature of ~3K.•Mn2VO4F possesses a condensed framework structure with disordered fluorine atoms.