Exploring reaction pathways in the hydrothermal growth of phase-pure bismuth ferrites

Phase-pure bismuth ferrites (BiFeO3 and Bi2Fe4O9) are grown using hydrothermal synthesis. In addition to varying the KOH, bismuth, and iron salt concentrations to tune which crystalline phases are formed, we identified that a 48h, pre-furnace, room temperature reaction is critical for the formation...

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Bibliographic Details
Published in:Journal of crystal growth 2017-06, Vol.468, p.104-109
Main Authors: Goldman, Abby R., Fredricks, Jeremy L., Estroff, Lara A.
Format: Article
Language:English
Subjects:
A1. Crystal growth reaction pathways
A1. Reaction intermediates
A2. Hydrothermal crystal growth
B1. Bismuth ferrite
B2. Multiferroic materials
Bismuth
Bismuth ferrite
Chemical synthesis
Crystal growth
Crystallization
Crystals
Ferrites
Morphology
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Summary:Phase-pure bismuth ferrites (BiFeO3 and Bi2Fe4O9) are grown using hydrothermal synthesis. In addition to varying the KOH, bismuth, and iron salt concentrations to tune which crystalline phases are formed, we identified that a 48h, pre-furnace, room temperature reaction is critical for the formation of phase-pure BiFeO3. To understand the reaction pathways leading to the different bismuth ferrite phases, we investigate the changes in composition of the intermediate products as a function of reagent concentrations and room temperature reaction times. During the syntheses that included a room temperature reaction, Bi25FeO40 is formed in the intermediate products, and BiFeO3 is the majority phase of the final products. The BiFeO3 crystals grown using this method are clusters of faceted subunits. These results indicate that forming Bi25FeO40 is a productive route to the formation of BiFeO3. Bi2Fe4O9 is formed via an alternate reaction pathway that proceeded via an amorphous precursor. This improved understanding of how hydrothermal synthesis can be used to control the phase-purity and morphology of bismuth ferrites opens doors to explore the multiferroic properties of BiFeO3 with complex morphologies. •We developed a robust and tunable synthesis of phase-pure BiFeO3 and Bi2Fe4O9.•A pre-furnace, room temperature reaction is critical for forming phase-pure BiFeO3.•BiFeO3 forms via Bi25FeO40, while Bi2Fe4O9 forms via an amorphous precursor.•The BiFeO3 crystals grown using this method are clusters of faceted subunits.
ISSN:0022-0248
1873-5002
DOI:10.1016/j.jcrysgro.2016.09.054