MnZn ferrite nanoscale particles were synthesized by hydrothermal method. The effects of amount of addition La3+ on the products were discussed. The product was characterized by X-ray diffraction （XRD） and transmiss...MnZn ferrite nanoscale particles were synthesized by hydrothermal method. The effects of amount of addition La3+ on the products were discussed. The product was characterized by X-ray diffraction （XRD） and transmission electron microscope （TEM）. The results show that the sample with 0.2% La3+（mass fraction） or without La3+ has only spinel phase, but the sample with mass fraction of La3+ exceeding 0.4% posses second phase besides the spinel one; and the nano-MnZn ferrites change from cube to hexagon when the mass fractions of La3+ is up to （1.2%.） TEM image of the sample with 1.2% La3+ indicates that the homogeneous hexagonal crystal is obtained and the particles are larger than those of undoped; the addition of La3+ has great influence on the crystallization of hydrothermal process and can change the shape of particles and improve their growth. The saturation magnetization of the sample with 1.2% La3+ (2.64 A·m2·kg-1) is lower than that of undoped (17.54 (A·m2·kg-1)) and it behaves superparamagnetically.展开更多
Mn1-xZnxFe2O4 thin films with various Zn contents and of different thickness were synthesized on glass substrates directly by electroless plating in aqueous solution at 90℃ without heat treatment.The Mn-Zn ferrite fi...Mn1-xZnxFe2O4 thin films with various Zn contents and of different thickness were synthesized on glass substrates directly by electroless plating in aqueous solution at 90℃ without heat treatment.The Mn-Zn ferrite films have a single spinel phase structure and well-crystallized columnar grains growing perpendicularly to the substrates.The results of conversion electron 57Fe M?ssbauer spectroscopy(CEMS)indicate that the cation distribution of Mn1-xZnxFe2O4 ferrite nanocrystal thin films fabricated by electroless plating is different from the bulk materials' and a great quantity of Fe3+ ions are still present on A sites for x>0.5.When the Zn content of the films increases,Fe3+ ions in the films transfer from A sites to B sites and the hyperfine magnetic field reduces,suggesting that Zn2+ has strong chemical affinity towards the A sites.On the other side,with the increase of the thickness of the films,Fe3+ ions,at B sites in the spinel structure,increase and the array of magnetic moments no longer lies in the thin film plane completely.At x = 0.5,Hc and Ms of Mn1-xZnxFe2O4 thin films show a minimum of 3.7 kA/m and a maximum of 419.6 kA/m,respectively.展开更多
文摘MnZn ferrite nanoscale particles were synthesized by hydrothermal method. The effects of amount of addition La3+ on the products were discussed. The product was characterized by X-ray diffraction （XRD） and transmission electron microscope （TEM）. The results show that the sample with 0.2% La3+（mass fraction） or without La3+ has only spinel phase, but the sample with mass fraction of La3+ exceeding 0.4% posses second phase besides the spinel one; and the nano-MnZn ferrites change from cube to hexagon when the mass fractions of La3+ is up to （1.2%.） TEM image of the sample with 1.2% La3+ indicates that the homogeneous hexagonal crystal is obtained and the particles are larger than those of undoped; the addition of La3+ has great influence on the crystallization of hydrothermal process and can change the shape of particles and improve their growth. The saturation magnetization of the sample with 1.2% La3+ (2.64 A·m2·kg-1) is lower than that of undoped (17.54 (A·m2·kg-1)) and it behaves superparamagnetically.
基金the National Natural Science Foundation of China(Grant No.90505007)
文摘Mn1-xZnxFe2O4 thin films with various Zn contents and of different thickness were synthesized on glass substrates directly by electroless plating in aqueous solution at 90℃ without heat treatment.The Mn-Zn ferrite films have a single spinel phase structure and well-crystallized columnar grains growing perpendicularly to the substrates.The results of conversion electron 57Fe M?ssbauer spectroscopy(CEMS)indicate that the cation distribution of Mn1-xZnxFe2O4 ferrite nanocrystal thin films fabricated by electroless plating is different from the bulk materials' and a great quantity of Fe3+ ions are still present on A sites for x>0.5.When the Zn content of the films increases,Fe3+ ions in the films transfer from A sites to B sites and the hyperfine magnetic field reduces,suggesting that Zn2+ has strong chemical affinity towards the A sites.On the other side,with the increase of the thickness of the films,Fe3+ ions,at B sites in the spinel structure,increase and the array of magnetic moments no longer lies in the thin film plane completely.At x = 0.5,Hc and Ms of Mn1-xZnxFe2O4 thin films show a minimum of 3.7 kA/m and a maximum of 419.6 kA/m,respectively.
