Inorganic Chemistry, Vol.59, No.4, 2299-2307, 2020
Molybdate-Tellurite Compounds with Capped-Kagome Spin-Lattices
Three new molybdate-tellurites, K2M9(TeO3)(4)(MoO4)(4)(OH)(4) (M = Ni-II and Co-II) and (NH4)(2)Cu-9(II)(TeO3)(4)(MoO4)(4)(OH)(4), have been successfully synthesized by conventional hydrothermal method. Due to the influence of the Jahn-Teller effect, these compounds crystallize in different space_ groups of rhombohedral R (3) over barm, monoclinic P2(1)/c and triclinic P (1) over bar for Ni-, Co-, and Cu-analogues, respectively. The topological arrangements of magnetic ions in these compounds show that deficient capped-kagome spin-lattices with kagome positions exhibit different 1/6 depletion. Magnetic and specific heat measurements confirm that K2Ni9(TeO3)(4)(MoO4)(4)(OH)(4) exhibits a spin-glass behavior at low temperature, while (NH4)(2)Cu-9(TeO3)(4)(MoO4)(4)(OH)(4) possesses a long-range canted antiferromagnetic ordering with T-N similar to 10.8 K and further shows a 3/5 magnetization plateau in the magnetization curve at low temperature.