Electronic conductivity and magnetization in the Mn-Fe-Zn-B-Al -Si-P-O system under crystallization

Abstract

The crystallization behavior of Fe2O3-doped Mn-Zn-B-Al-Si-P-O glass system was studied in relation to their magnetic and electrical properties. The glass containing 27 mol% Fe2O3 remained predominantly amorphous and enabled controlled nanocrystallization upon thermal treatment, forming iron-rich crystallites of 40–120 nm. Nanocrystallization increased DC conductivity from 10−11 S⋅cm−1 to 10−8 S⋅cm−1 at 272 K, and reduced activation energy of polaron hopping from 0.82 to 0.43 eV, disorder from 0.29 to 0.25 eV, and optical phonon frequency from ∼2.5⋅1013–1.9 ⋅ 1013 Hz. A partially crystalline reference sample with 40 mol% Fe2O3 showed outer and inner regions enriched in ferromagnetic Fe3O4 and antiferromagnetic Fe2O3, respectively. Its highest conductivity, ∼10−4 S⋅cm−1, was attributed to ∼50% of iron oxide crystallites facilitating charge transport. Magnetic measurements revealed antiferromagnetic features after nanocrystallization linked to nanoscale α-Fe2O3, whereas the reference glass-ceramic showed ferromagnetic hysteresis due to the presence of Fe3O4 crystallites.