Synthesis and crystal structure of multicomponent ceramics YBa2CuR2O6 and YBa4R3O9 (R = Cu, Mg, Zn, Ni, Co)

Abstract

High entropy oxides YBa₂CuR₂O₆ and YBa₄R₃O₉ have been synthesized by the method of solid-phase synthesis from a charge, which contains such common counterparts as BaCO₃, Y₂O₃ and CuO along with the equimolar mixture of oxides CuO, MgO, ZnO, NiO and CoO (conditionally labelled as RO). Phase composition and crystal structure refinement of the products synthesized has been provided by X-ray powder diffraction. It has been shown that a well known rhombic compound r-YBa2Cu3O7 with a = 0. 3834(2) nm, b = 0. 3888(2) nm, c = 0. 3888(2) nm is formed under the conditions of solid-phase synthesis carried out without the use of a multicomponent mixture of oxides. While the use of RO oxide in the charge leads to the formation of phases related to the known structural types of t-YBa₂Cu₃O₆ and YBa₄Cu₃O₉, namely, the tetragonal phase YBa₂CuR₂O₆ with a = 0. 3877(2) nm, c = 1. 1632(7) nm and the cubic phase of YBa₄R₃O₉ with a = 0. 8228(2) nm. Analysis of the atom’s location in the regular systems of points of structures of multicomponent phases YBa₂CuR₂O₆ and YBa₄R₃O₉ indicates that the conditional “high-entropy” cationic component R = CuMgZnNiCo occupies only the position with an octahedral environment of oxygen atoms in these structures. Therefore, if there are positions with an octahedral RO6 environment in the designed multicomponent oxide compounds, the use of “high-entropy” component of the charge R = Cu, Mg, Zn, Ni, Co to create new single-phase high entriopy oxide materials with oxygen is very effective.