High-Temperature and High-Pressure Aqueous Solution Formation, Growth, Crystal Structure, and Magnetic Properties of BiFeO₃ Nanocrystals

In situ synchrotron radiation powder X-ray diffraction (SR-PXRD) was applied to study the formation and growth of BiFeO 3 nanocrystals, revealing that phase pure BiFeO 3 can be obtained in high-temperature, high-pressure aqueous solution using Bi(NO 3 ) 3 and Fe(NO 3 ) 3 ·9H 2 O as precursors and KOH as mineralizer. The method gives a rapid way for preparation of nanomaterials, and the formation of BiFeO 3 can be finished within seconds after its initial nucleation in near-critical aqueous solution. As proof of concept BiFeO 3 nanocrystals were subsequently synthesized in a continuous flow supercritical system and for reference also in autoclaves. High resolution multitemperature SR-PXRD data were measured between 100 and 1000 K with a step size of 100 K. The magnetic properties of both the autoclave and the continuous flow samples are studied.