CRYSTAL STRUCTURE OF THE COMPOUND Ba₂GdRuO₆

Abstract

The work investigated the crystal structure of the double perovskite Ba₂GdRuO₆ by X-ray powder diffraction. X-ray phase analysis was performed, which confirmed the single-phase nature of the sample. Using the TREOR module of the HighScore Plus 3.0 program, the diffraction pattern was indexed and the space symmetry group I41/amd (141) of the tetragonal system with unit cell parameters a=b=2.478 Å, c=11.897 Å was determined. The microstructural parameters of the crystal lattice were refined using the Rietveld method using correlation matrices. The discrepancy factor is R=3.93%, which indicates the high quality of the structural model. The coordinates of the Ba, Gd, Ru, and O atoms in the structure were established, their Wyckoff positions and filling factors were determined. It is shown that the structure is a typical double perovskite A₂BB'O₆, where gadolinium (Gd³⁺) and ruthenium (Ru⁵⁺) atoms form regular octahedra with six oxygen atoms each, located in positions 8c and 8d, respectively, with a coordination number Z=6. Barium atoms occupy large cavities between the octahedra, and oxygen forms intermetallic bridges, ensuring the coherence of the structure. This structure is typical of materials with magnetic and electrical properties that are interesting for materials physics. Literature data on the magnetic, electronic, mechanical, and thermoelectric properties of Ba₂GdRuO₆ are analyzed. The material exhibits complex magnetic behavior with competition of antiferromagnetic and ferrimagnetic phases, a Curie temperature of 60 K, is a semiconductor with a band gap of about 1 eV, and exhibits high thermoelectric efficiency at elevated temperatures. The proposed crystal structure for the compound Ba2GdRuO6 can be determined in further studies using the diffraction spectrum recorded by the powder method with the Bragg-Brentano imaging geometry in a wider range. It is also possible to synthesize a single crystal of this compound and study the crystal structure by the single crystal method.