Open AccessПарамагнитные антисайт Mn-дефекты в нанокерамике алюмомагниевой шпинели
Author(s) -
Анатолий Федорович Зацепин,
Арсений Николаевич Киряков,
Дамир Рафисович Байтимиров,
Т. В. Дьячкова,
Александр П. Тютюнник,
Юрий Галиулович Зайнулин
Publication year - 2020
Publication title -
fizika tverdogo tela
Language(s) - English
Resource type - Journals
eISSN - 1726-7498
pISSN - 0367-3294
DOI - 10.21883/ftt.2020.01.48744.568
Subject(s) - electron paramagnetic resonance , manganese , paramagnetism , impurity , spinel , materials science , hyperfine structure , lattice constant , crystal structure , analytical chemistry (journal) , single crystal , microcrystalline , crystallography , chemistry , nuclear magnetic resonance , condensed matter physics , atomic physics , metallurgy , physics , organic chemistry , chromatography , diffraction , optics
The influence of structural and dimensional factors on the formation of intrinsic and impurity paramagnetic centers in nanoceramics of aluminum-magnesium spinel is studied. The studied samples (with a grain size of 30 nm) were obtained by thermobaric synthesis. Microcrystalline ceramics and a MgAl2O4 single crystal were used as standards. The single crystal and microceramics contain characteristic Mn2+ paramagnetic centers (hyperfine structure constant (HFS) A = 82 G). In the studied nanoceramic samples in the initial state, both impurity Mn2+ and intrinsic F+ centers are detected. In contrast to nanoceramics, in reference samples centers of the F+ type appear only after irradiation with 130 keV by accelerated electrons. The parameters of the Mn2+ centers in nanoceramics differ significantly from those in microceramics and single crystals. For the Mn2+ center in nanoceramics, the EPR signal is characterized by two anomalous HFS constants (A1 = 91.21 G, A2 = 87.83 G) caused by two varieties of octahedrally coordinated manganese ions (anti-site defects [Mn2+]Al3+). The specific features of the spectral parameters of manganese centers correlate with a decrease in the lattice parameter of MgAl2O4 in the nanostructured state. The observed effects are interpreted based on the proposed charge compensation scheme of [Mn2+]Al3+ with an aluminum anti-site defect and an F+ center.