Ba(CrTe)TeO: in Search of Jahn-Teller Distorted Cr(II) Oxide.

A novel 6H-type hexagonal perovskite Ba(CrTe)TeO was prepared at high pressure (6 GPa) and temperature (1773 K). Both transmission electron microscopy and synchrotron powder X-ray diffraction data demonstrate that Ba(CrTe)TeO crystallizes in P6/mmc with face-shared (CrTe)O octahedral pairs interconnected with TeO octahedra via corner-sharing. Structure analysis shows a mixed Cr/Cr valence state with ∼10% Cr. The existence of Cr in Ba(CrCrTe)TeO is further evidenced by X-ray absorption near-edge spectroscopy. Magnetic properties measurements show a paramagnetic response down to 4 K and a small glassy-state curvature at low temperature. In this work, the octahedral CrO component is stabilized in an oxide material for the first time; the expected Jahn-Teller distortion of high-spin (d) Cr is not found, which is attributed to the small proportion of Cr (∼10%) and the face-sharing arrangement of CrO octahedral pairs, which structurally disfavor axial distortion.