Phase transitions in novel Li-containing honeycombs, Li₈Cr₂(Te/Sb)₂O₁₂

Honeycomb frameworks of Li₈M₂(Te/Sb)₂O₁₂ (M = transition metal), present interesting magnetic phenomena related to frustrated two-dimensional lattices of spins. In the present work, polycrystalline Li₈Cr₂(Te/Sb)₂O₁₂ were synthesized by standard solid-state route. Powder X ray diffraction patterns were recorded to check the phase formation and purity. C_2/m space group was confirmed using Rietveld analysis and lattice parameters are determined to be a=5.141Å, b=8.884Å, c=5.143Å, β=109.5Å for Li₈Cr₂Sb₂O₁₂, and a=5.128Å, b=8.850 Å, c=5.151Å, β=109.8Å for Li₈Cr₂Te₂O₁₂, presenting diminished unit cell sizes compared to that of Li8Co2Te2O12 are a=5.226Å, b=8.892Å, c=5.160Å, β=110.9Å. In the case of Li₈Cr₂Sb₂O₁₂ a magnetic phase transition is present at 7.4 K as determined from the derivative, dCp/dT. A similar transition is found in Li₈Co₂Te₂O₁₂ at 9.5 K. Neutron diffraction is underway for comprehending cationic ordering, crystal, and magnetic structure of Li₈Cr₂(Te/Sb)₂O₁₂ as well as its mixed occupancy of the 4g Wyckoff position in the C_2/m space grpup. Our experimental results will highlight the magnetism of the honeycomb layers of Cr and the ionic diffusion of inter-layer Lithium and will be of interest to magnetism as well as battery research.