Effect of spatial constraints on the phase evolution of YFeO3-based nanopowders under heat treatment of glycine-nitrate combustion products

Abstract Formation and structural transformations of yttrium orthoferrite crystals have been studied using X-ray diffractometry, Mossbauer spectroscopy and transmission electron microscopy combined with electron microdiffraction. Said processes have been studied under heat treatment of glycine-nitrate combustion products. There have been identified formations of three structural yttrium orthoferrite modifications – amorphized hexagonal h 1 > -YFeO 3 ( P 6 3 cm ) and nanocrystalline hexagonal h 2 -YFeO 3 ( P 6 3 /mmc ), as well as nanocrystalline orthorhombic o -YFeO 3 ( Pbnm ), which are selectively formed depending on available three-dimensional confinements. Based on the analysis of changes in the fluid and size composition formulation, it has been proposed mechanism for formation and transformation of YFeO 3 nanocrystals, including growth stage of h 2 -YFeO 3 crystals due to amorphized phase of h 1 > -YFeO 3 up to critical size of about 15 nm and their subsequent transformation into orthorhombic form o -YFeO 3 .