Nanoparticle-containing glasses co-doped with transition and rare earth elements: comparative studies of transparent magnets

A comparative multitechnique study (including transmission electron microscopy, synchrotron radiation, static magnetisation, magnetic circular dichroism and electron magnetic resonance) has been carried out of nanoparticle-containing borate glasses of two different types: (i) with iron and manganese oxide additives and (ii) with iron and rare earth oxide additives. Due to the presence of magnetic nanoparticles, these glasses have a nonlinear magnetic field dependence of magnetization with hysteresis and saturation while remaining transparent in the visible and near-infrared spectral ranges. The nature of the nanoparticles has been identified as manganese ferrite for type (i) glasses and maghemite for type (ii) glasses. The synchrotron radiation studies as well as the computer-assisted electron magnetic resonance provide an insight into the morphological characteristics of the magnetic nanoparticles in the glass.