Open AccessМагнитные свойства легированных натрием композитов типа фуллерен-терморасширенный графит
Author(s) -
В.И. Берёзкин,
В.В. Попов,
С.В. Кидалов,
Н.В. Шаренкова
Publication year - 2019
Publication title -
fizika tverdogo tela
Language(s) - English
Resource type - Journals
eISSN - 1726-7498
pISSN - 0367-3294
DOI - 10.21883/ftt.2019.10.48251.477
Subject(s) - magnetic moment , paramagnetism , materials science , analytical chemistry (journal) , graphite , ferromagnetism , condensed matter physics , chemistry , composite material , physics , chromatography
The magnetic properties (field range H = 0–50 kOe, temperature range T = 3–300 K), and structural features of a sodium-doped carbon composite material based on fullerene C_60 and thermally exfoliated graphite (TEG) are studied. The material is obtained with different ratios of the components by sintering at a pressure of 7 GPa and T = 600°C, at which it is found that significant amorphization of the crystal lattice of the initial C_60 occurs. The dia-, para-, and ferromagnetic components ( M _D, M _PM, and M _FM) were separated from the total magnetic moment of the samples under study. It is found that a sodium dopant has no effect on the magnetic properties of the composite. Analysis of the M _PM( H ) field dependences by using the Brillouin function for the fullerene-containing sample (i.e., without TEG) makes it possible to determine the quantum number of the total angular momentum of paramagnetic (PM) centers. Its value is found to be J = 1, which corresponds to elementary magnetic moment μ_PM = 2μ_B of a PM center. The concentration of PM centers is estimated at the level of N _PM ≈ (2–5) × 10^18 g^–1 for most samples, including the material without TEG. The introduction of TEG into the initial composition and an increase in its proportion in the composite leads to a strong increase in the magnetic moment, which is explained by an increase in both the J value and the concentration of PM centers.