In-situ formation of barium ferrite in iron doped “tetragonal tungsten bronze”: Elaboration of room temperature multiferroic composites

Recent studies of ceramics of formula Ba2LnFeNb4O15 (Ln = rare earth) with the “tetragonal tungsten bronze” (TTB) structure have correlated their room temperature multiferroics properties to the occurrence of barium ferrite parasitic phases. This work presents the elaboration of Ba2LaFeNb4O15 and Ba2EuFeNb4O15 composite samples with an excess of hematite in the TTB nominal composition. The influence of crystal-chemistry on the phase content and properties of Ba2LnFeNb4O15 TTB composites is discussed. A particular focus on the mechanisms related to the in-situ formation of barium ferrite is given. We show that we can control the spurious ferrite phase in TTB multiferroic composites and thus modulate their magnetic response.