spectrum of a partly superparamagnetic specimen is shown in Figure 8.22, whereby
the superposition of a doublet with a sextet can be seen. The doublet characterizes
the superparamagnetic fraction of the specimen, whereas the sextet is the “fingerprint” of the conventional magnetic fraction of the specimen. Clearly, the specimen
consisted of a material with a relatively broad particle size distribution, where a
certain fraction with the smaller particle size was superparamagnetic. The remainder of the specimen shows the spectrum of conventional magnetic materials.
The situation is different in the case of the spectra shown in Figures 8.23 and 8.24,
which depict M€ ossbauer spectra of two different superparamagnetic ferrites. The
spectrum displayed in Figure 8.23 stems from a c-Fe 2 O 3 specimen, measured at
Figure 8.22 M€ ossbauer spectrum of a partly
superparamagnetic specimen. The
experimental data are fitted with two magnetic
sites: (i) a quadrupole site stemming from the
superparamagnetic fraction of the specimen
with the small particle size, represented by the
central doublet, and (ii) a conventional
magnetic site, attributed to the part of the
specimen with the larger particle size, leading
to the sextet.
Figure 8.23 M€ ossbauer spectrum of ZrO 2 -coated c-Fe 2 O 3 particles determined at 300 K. The
spectrum consists only of the doublet representing superparamagnetic material.
188j 8 Magnetic Properties of Nanoparticles
the superposition of a doublet with a sextet can be seen. The doublet characterizes
the superparamagnetic fraction of the specimen, whereas the sextet is the “fingerprint” of the conventional magnetic fraction of the specimen. Clearly, the specimen
consisted of a material with a relatively broad particle size distribution, where a
certain fraction with the smaller particle size was superparamagnetic. The remainder of the specimen shows the spectrum of conventional magnetic materials.
The situation is different in the case of the spectra shown in Figures 8.23 and 8.24,
which depict M€ ossbauer spectra of two different superparamagnetic ferrites. The
spectrum displayed in Figure 8.23 stems from a c-Fe 2 O 3 specimen, measured at
Figure 8.22 M€ ossbauer spectrum of a partly
superparamagnetic specimen. The
experimental data are fitted with two magnetic
sites: (i) a quadrupole site stemming from the
superparamagnetic fraction of the specimen
with the small particle size, represented by the
central doublet, and (ii) a conventional
magnetic site, attributed to the part of the
specimen with the larger particle size, leading
to the sextet.
Figure 8.23 M€ ossbauer spectrum of ZrO 2 -coated c-Fe 2 O 3 particles determined at 300 K. The
spectrum consists only of the doublet representing superparamagnetic material.
188j 8 Magnetic Properties of Nanoparticles