Cadmium copper selenite chloride, CdCu2(SeO3)2Cl2, an insulating spin gap system

Article abstract of DOI:10.1016/j.jssc.2021.122518

Novel copper cadmium selenite chloride has been synthesized via vapor transport reaction as well as by solid state process. CdCu₂(SeO₃)₂Cl₂ crystallizes in a monoclinic space group I2/a with cell constants a ?= ?7.8057(3) ?, b ?= ?9.6036(4) ?, c ?= ?10.7817(5) ? and β ?= ?102.362(4)°, Z ?= ?4. Its crystal structure can be described as an open channel three-dimensional framework, formed by [CdO₂Cl₄] and [CuO₄Cl₂] polyhedra interconnected by pyramidal SeO₃ groups. The copper polyhedra form magnetically isolated dimers with a spin gap Δ ?= ?38.7 ?± ?0.8 ?meV, as defined from magnetic susceptibility measurements. The electron band gap estimated by diffuse reflectance method E_g ?= ?2.82 ?± ?0.02 ?eV is in agreement with the yellow-green color of the substance. Density functional theory provides the values of electron (2.4 ?eV) and spin (36.6 ?meV) gaps consistent with experimental observations.