Structural infection and anomalous phase sequences in complex oxides prepared from nanodispersed components

Abstract

The complex oxides prepared by solid-phase synthesis from nanoscopic components are studied using X-ray diffraction. It is demonstrated that the use of nanoscopic components in the solid-phase synthesis of lutetium borate LuBO₃ and europium molybdate Eu₂(MoO₄)₃ leads to anomalous sequences of phase transformations in these compounds: the vaterite ⇒ calcite ⇔ vaterite sequence for LuBO₃ and the β ⇒ α ⇔ β sequence for Eu₂(MoO₄)₃ are observed instead of the previously known sequences, namely, the calcite ⇔ vaterite sequence for LuBO₃ and the α ⇔ β sequence for Eu₂(MoO₄)₃. The revealed anomalous sequences do not depend on the procedure used for preparing reactants and are determined by the nanoscopic sizes of the initial components. It is found that microscopic additions of a number of simple oxides can suppress the kinetics of solid-phase synthesis of particular complex oxides and initiate the formation of new phases in the synthesis of other complex oxides (the so-called structural infection effect).