Microwave and magneto-optic properties of ε-Fe₂O₃ nanoparticles arising in borate glasses doped with Fe and Gd

Abstract

The ε-Fe2O3 nanoparticles in borate glasses co-doped with low concentrations of Fe2O3 and Gd2O3 were investigated with two experimental techniques – visible magnetic circular dichroism (MCD) and electron spin resonance (ESR). The most prominent features of the MCD spectra are: non-linear dependence of the spectral maxima intensities on the Gd concentration and strong increase with the temperature decrease. The ESR spectra of these glasses exhibit two features with g = 4.3 due to the diluted Fe3+ ions and 2.0 associated both with Fe3+ ions and with nanoparticles. The integrated spectra intensities do not follow the T-1 Curie law suggesting a considerable contribution from the magnetically ordered nanoparticles to ESR. Analysis of the MCD and ESR concentration dependences allow suggestion on the Gd ions incorporation into nanoparticles.

Effect of gadolinium on magnetic circular dichroism and electron magnetic resonance of ε-Fe2O3 nanoparticles formed in borate glasses

“…Recently, we have reported a new possibility of obtaining ε-Fe 2 O 3 nanoparticles: their spontaneous formation in the course of devitrification and subsequent thermal treatment of Al 2 O 3 -K 2 O-B 2 O 3 glasses co-doped with low contents of Fe 2 O 3 and Gd 2 O 3 [43][44][45]. However, the role of gadolinium in the nanoparticle formation and its effect on the nanoparticle properties has not been elucidated in our previous works.…”

“…Prior to MCD and EMR studies, the samples were characterized by structural and static magnetic measurements. In order to provide a comprehensive analysis of our results concerning ε-Fe 2 O 3 nanoparticles formed in borate glasses, we have used certain structural and EMR data reported in our previous publications [43][44][45].These data are shown in Figs. 2, 3 and 9 a.…”