Structure and magnetism of novel mixed-anionic-group compounds M2(SeO3)(Te3O7) (M = Co2+, Ni2+)

Novel mixed-anionic-group compounds M-2(SeO3)(Te3O7) (M = Co2+, Ni2+) are successfully synthesized by a conventional hydrothermal method. Two compounds are isostructural which crystallize in the orthorhombic system of a space group Pnma. The framework shows a (MO6)(infinity) chain structure along the b-axis, while SeO3 groups are isolated and Te3O7 groups form the (Te3O7)(infinity) chains running along the aaxis. This is the first time to realize transition-metal compounds coexisting with Se4+ and Te4+ anionic groups. Magnetic measurements show that Co-2(SeO3)(Te3O7) possesses an antiferromagnetic ordering at similar to 11 K, while Ni-2(SeO3)(Te3O7) exhibits a similar antiferromagnetic ordering at similar to 31 K. Also, the fitting of magnetic susceptibility using a spin-chain model gives the exchange coupling J/kB = -1.515 K for Co-2(SeO3)(Te3O7) and J/kB = -8.963 K for Ni-2(SeO3)(Te3O7), respectively. (C) 2017 Elsevier B.V. All rights reserved.