Distribution of Cobalt Co2+ Ions in Single Crystals of Spinel Li0.5Ga2.5O4

• Published in: Physics of metals and metallography Vol. 125; no. 1; pp. 27 - 32
• Main Authors: Shapovalov, V. V., Shapovalov, V. A., Drokina, T. V., Vorotynov, A. M., Val’kov, V. I.
• Format: Journal Article
• Language: English
• Published: Moscow Pleiades Publishing 2024; Springer Nature B.V
• Subjects: Chemistry and Materials Science; Cobalt; Crystal lattices; Electrical and Magnetic Properties; Electron paramagnetic resonance; Gallium; Lithium ions; Materials Science; Metallic Materials; Oxygen ions; Single crystals; Spectra; Spinel; Symmetry; Unit cell; structurally nonequivalent positions of ions; electron paramagnetic resonance; crystal lattice; unit cell; spinel single crystal
• ISSN: 0031-918X; 1555-6190
• DOI: 10.1134/S0031918X23602883

The distribution of Co 2+ ions over sublattices and structurally nonequivalent positions in the unit cell of the crystal lattice of a single crystal of lithium gallium spinel Li 0.5 Ga 2.5 O 4 is shown. This distribution determines the properties of both mono- and nanocrystalline substances. The distribution is obtained by a special technology and is manifested in the electron paramagnetic resonance (EPR) spectra. The distribution of Co 2+ ions depends on the structural and magnetic nonequivalence. The structural and magnetic nonequivalence causes a multiminimum behavior of the crystal field potential in the unit cells of single crystals at the locations of Co 2+ ions. The Co 2+ ions are found in complexes with tetrahedral and octahedral oxygen ions. Three types of EPR spectra of Co 2+ ions have been found and investigated. The spectrum is attributed to the Co 2+ ion, which replaces the Ga 3+ ion located in a tetrahedral oxygen environment. The spectrum of the ion located in the crystal field with axial symmetry belongs to the Co 2+ ion replacing the Li + ion located in an octahedral oxygen environment. The spectrum of the ion located in a low symmetry crystal field belongs to the Co 2+ ion replacing the Ga 3+ ion located in an octahedral oxygen environment. The nearest cationic environment of the ion creates rhombic distortions due to the different valence numbers of Li + and Ga 3+ . The results of studying the angular dependences of the spectra show the presence of four and twelve magnetically nonequivalent positions in the unit cells.