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

IF 1.1 4区材料科学 Q3 METALLURGY & METALLURGICAL ENGINEERING

Physics of Metals and Metallography Pub Date : 2024-04-21 DOI:10.1134/s0031918x23602883

V. V. Shapovalov, V. A. Shapovalov, T. V. Drokina, A. M. Vorotynov, V. I. Val’kov

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Abstract

The distribution of Co²⁺ ions over sublattices and structurally nonequivalent positions in the unit cell of the crystal lattice of a single crystal of lithium gallium spinel Li_0.5Ga_2.5O₄ 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 Co²⁺ 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 Co²⁺ ions. The Co²⁺ ions are found in complexes with tetrahedral and octahedral oxygen ions. Three types of EPR spectra of Co²⁺ ions have been found and investigated. The \({\text{Co}}_{{{\text{tetr}}}}^{{2 + }}\) spectrum is attributed to the Co²⁺ ion, which replaces the Ga³⁺ ion located in a tetrahedral oxygen environment. The spectrum of the \({\text{Co}}_{{{\text{oct}}}}^{{2 + }}\) ion located in the crystal field with axial symmetry belongs to the Co²⁺ ion replacing the Li⁺ ion located in an octahedral oxygen environment. The spectrum of the \({\text{Co}}_{{{\text{oct}}}}^{{2 + }}\) ion located in a low symmetry crystal field belongs to the Co²⁺ ion replacing the Ga³⁺ 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 Ga³⁺. The results of studying the angular dependences of the spectra show the presence of four and twelve magnetically nonequivalent positions in the unit cells.

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尖晶石 Li0.5Ga2.5O4 单晶中 Co2+ 钴离子的分布

摘要展示了 Co2+ 离子在锂镓尖晶石 Li0.5Ga2.5O4 单晶体晶格单元格中的亚晶格和结构非等价位置上的分布。这种分布决定了单晶和纳米晶物质的特性。该分布是通过一种特殊技术获得的，并在电子顺磁共振（EPR）光谱中得到体现。Co2+ 离子的分布取决于结构和磁性非等价性。结构和磁性非等价性会导致单晶体单元格中 Co2+ 离子所在位置的晶体场势出现多重最小值。Co2+ 离子与四面体和八面体氧离子形成络合物。发现并研究了 Co2+ 离子的三种 EPR 光谱。({\text{Co}}_{{\text{tetr}}}}^{2+ }}/)光谱归因于 Co2+离子，它取代了位于四面体氧环境中的 Ga3+离子。位于轴对称晶场中的\({text{Co}}_{{text{oct}}}}^{{2 + }}\) 离子的光谱属于 Co2+ 离子，它取代了位于八面体氧环境中的 Li+ 离子。位于低对称性晶场中的\({text{Co}}_{{text{oct}}}}^{2 + }}\) 离子的光谱属于 Co2+ 离子取代了位于八面体氧环境中的 Ga3+ 离子。由于 Li+ 和 Ga3+ 的价数不同，离子的最近阳离子环境产生了菱形畸变。对光谱角度依赖性的研究结果表明，在单元格中存在四个和十二个磁性非等价位置。

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来源期刊

Physics of Metals and Metallography 工程技术-冶金工程

CiteScore

2.00

自引率

25.00%

发文量

108

审稿时长

3 months

期刊介绍： The Physics of Metals and Metallography (Fizika metallov i metallovedenie) was founded in 1955 by the USSR Academy of Sciences. Its scientific profile involves the theory of metals and metal alloys, their electrical and magnetic properties, as well as their structure, phase transformations, and principal mechanical properties. The journal also publishes scientific reviews and papers written by experts involved in fundamental, application, and technological studies. The annual volume of publications amounts to some 250 papers submitted from 100 leading national scientific institutions.