Two ternary columnar composite crystals, Ba15Zr14Se42 and Sr21Ti19Se57, have been characterized and modeled three-dimensionally [1] and they are stated to have a commensurate crystal structure similar to several incommensurate ternary sulfur compounds [2]–[6]. To evaluate whether the two columnar compounds are isostructural to the sulfur compounds they need to be modelled four-dimensionally.Two composite selenium compounds have been studied and compared to similar sulfur compounds to investigate if they possess the same crystal structure
