Synthesis, crystal structures, magnetic properties, and lattice dynamics of Ba2XCu(OH)[V2O7] with X=Cl, Br

• Crystal structure of two salt-inclusion vanadates.
• Tuning the crystal morphology through pH-control in hydrothermal synthesis.
• DFT calculations, IR and Raman data for studies on lattice dynamics.
• Magnetic chain compounds: antiferromagnetic S=1/2 Heisenberg systems.

We have synthesized Ba2XCu(OH)[V2O7] with X=Cl, Br by hydrothermal methods. The isotypic structures (Pnma, Z=4, a≈15.1 Å, b≈6.1 Å, c≈9.6 Å) contain distorted hexagonal layers of Ba and X   in a BN-type arrangement. Each halide is further coordinated by one out-of plane Ba atom in an alternate up-down fashion resulting in an overall Ba2X3+∞2 structural feature. The planar Ba–X   hexagonal rings are centered by divanadate groups in an eclipsed orientation. Edge-sharing chains of CuO2/2(OH)2/2O2/15-∞1 complement the structure. The magnetic properties are associated with the magnetic Cu2+ ions and can be described as an antiferromagnetic quasi 1D S=1/2 Heisenberg system. Confirmation is obtained from both magnetic and specific heat measurements. Furthermore, lattice dynamics are studied by DFT methods, IR, and Raman spectroscopy.

Crystals of Ba2BrCu(OH)[V2O7] (left) and structural motif (right).Figure optionsDownload as PowerPoint slide