Synthesis of magnetic and multiferroic materials from polyvinyl alcohol-based gels

This review article summarizes results on the synthesis of the magnetic materials including modified nickel ferrite (Ni0.9Co0.1Cu0.1Fe1.9O4−δ), yttrium iron garnet (Y3Fe5O12), lanthanum-containing manganites (MхLa1−хMnO3 (М=Pb, Ba or Sr; x=0.3−0.35)), and multiferroics (BiFeO3 and BiFe0.5Mn0.5O3) from polyvinyl alcohol-based gels. It is shown that the ammonium nitrate accelerates destruction of organic components of xerogels and thus Ni0.9Co0.1Cu0.1Fe1.9O4−δ and BiFeO3 can be prepared at record low temperatures (100 and 250 °С, respectively) which are 200-300 °С lower compared to the process where air is used as an oxidizing agent. As for the synthesis of Y3Fe5O12, MхLa1−хMnO3 and BiFe0.5Mn0.5O3, the presence of NH4NO3 favors formation of foreign phases, which ultimately complicate reaction mechanisms and lead to the higher temperature to synthesize target products. Developed methods provide nanoscale magnetic and multiferroic materials with an average particle size of ∼20-50 nm.