A new oxytelluride: Perovskite and CsCl intergrowth in Ba3Yb2O5Te

The new oxytelluride Ba3Yb2O5Te was obtained from an alkaline earth flux. Ba3Yb2O5Te crystallizes in the tetragonal space group P4/mmm (#123), with a=4.3615(3)Å and c=11.7596(11)Å, Z=1. The structure combines two distinct building blocks, a Ba2Yb2O5 perovskite-like double layer with square bipyramidal coordination of the ytterbium ions, and a CsCl-type BaTe layer. Short range magnetic order is apparent at below 5K, with the magnetic behavior above this temperature dominated by crystal field effects. The structure may be considered as an analog to the Ruddlesden–Popper phases, where the NaCl-type layer has been replaced by the CsCl-type layer. The two-dimensional magnetic behavior is expected based on the highly anisotropic nature of the structure. Optical images of Ba3Yb2O5Te in transmission (left) and reflected (right) light, with atomic unit cell overlay. [Display omitted] •Single crystal synthesis and characterization of a new phase, Ba3Yb2O5Te.•The structure features the BaTe high pressure polymorph intergrowth.•Magnetic susceptibility measurements show short range 2 dimensional ordering.•Heat capacity measurements show a feature at the magnetic ordering temperature.•Optical reflectivity measurements show a 2F7/2→2F5/2 absorption at 976nm.