Synthesis and Phase Composition of Fe/Mn Containing Nanocrystals in Glasses from the System Na_2O/MnO/SiO_2/Fe_2O_3

摘要

Oxide glass-ceramics containing ferrimagnetic nanocrystals are of fundamental and practical interest due to their electrical and magnetic properties. Depending on phase composition, size and volume fraction of the crystalline phase formed, the precipitated crystals are applied as parts of ferrofluids, in magnetic resonance imaging and as parts of biomagnetic sensors for the detection of different chemical and biochemical substances. In the present investigation, glasses from the system Na_2O/MnO/SiO_2/Fe_2O_3 are produced by the conventional melting technique; after applying appropriate time-temperature programs, the nanocrystalline magnetic phase is precipitated in a glass matrix. The phase composition and microstructure of the formed glass-ceramics is studied by x-ray diffraction, and scanning and transmission electron microscopy. Anomalous small angle x-ray scattering experiments are used to gather information about the phase composition and structure of the nano-sized crystals formed, as well as about their size distribution.