Solid Solution Studies of Layered Honeycomb-Ordered Phases O3-Na3M2SbO6 (M = Cu, Mg, Ni, Zn)

This is an author's peer-reviewed final manuscript, as accepted by the publisher. The published article is copyrighted by Elsevier and can be found at: http://www.journals.elsevier.com/journal-of-solid-state-chemistry/.Complete solid solutions with the composition Na₃M₂₋ₓM’ₓSbO₆ where M, M’ = Cu, Mg, Ni, Zn have been synthesized by conventional solid state techniques and were investigated using X-ray diffraction, magnetism and optical measurements. All compositions crystallize in a monoclinic unit cell and exhibit a layered structure with a honeycomb cationic ordering within the slabs. These compounds also exhibit Curie-Weiss behavior at high temperatures and the magnetic moment values verify the presence of Cu²⁺ and/or Ni²⁺. The antiferromagnetic order of Na₃Ni₂SbO₆ is suppressed upon substitution of Ni²⁺ with Mg²⁺ or Zn²⁺. The spin gap observed in Na₃Cu₂SbO₆ is also suppressed by substitution of Cu²⁺ with Mg²⁺ or Zn²⁺. The Na₃Ni₂₋ₓCuₓSbO₆ compositions follow an expected transition from an antiferromagnetic ordering to the spin gap of the copper end member. The estimated band gaps for these compounds have been estimated from diffuse reflectance measurements