A comparative study of $\gamma$-Fe$_2$O$_3$ and $\epsilon$-Fe$_2$O$_3$ nanoparticles arising in borate glasses doped with Fe and Gd

Formation and properties of the iron oxides $\gamma$-Fe$_2$O$_3$ and $\epsilon$-Fe$_2$O$_3$ nanoparticles arising in glasses of basic compositions Ge$_2$O-K$_2$O-Al$_2$O$_3$-B$_2$O$_3$ and K$_2$O-Al$_2$O$_3$-B$_2$O$_3$ doped with different concentrations of Fe$_2$O$_3$ and Gd$_2$O$_3$ and subjected to the additional thermal treatment are studied. The X-ray diffraction, TEM microscopy, magnetooptical effects, and electron spin resonance study allow elucidating the matrix and Gd role in determining the nanoparticle properties.