Shape controllable synthesis of NdFeO3 micro single crystals by a hydrothermal route

Abstract

Orthorhombic NdFeO₃ (space group: Pnma) crystals with controlled morphologies and sizes were synthesized via a hydrothermal method. The morphologies of the final products strongly depend on the concentration of alkali. When the concentration of the KOH solution was adjusted from 16 M to 19 M, cuboid, cross-shaped and bar-shaped NdFeO₃ crystals were obtained respectively. The bar-shaped NdFeO₃ crystals are preferentially oriented along the direction of [010]. The formation of NdFeO₃ crystals can be explained by a “dissolution–precipitation” mechanism. It is interesting to find that if the precipitates are isolated by centrifugation before hydrothermal treatment, then mixed with KOH solutions, followed by adding an appropriate amount of KNO₃, the rod-shaped NdFeO₃ crystals with high aspect ratio and small size will be obtained in the hydrothermal route. The magnetic properties of NdFeO₃ crystals with different shapes were also explored.