Oriented Nanomagnets Originating from Topotactic and Pseudomorphic Reactions

Mathias I. Mørch; Jack Thomas-Hunt; Amalie P. Laursen; Jesper Simonsen; Jens Plum Frandsen; Harikrishnan Vijayan; Mogens Christensen

doi:10.1021/acs.chemmater.3c02616

Oriented Nanomagnets Originating from Topotactic and Pseudomorphic Reactions

Mathias I. Mørch, Jack Thomas-Hunt, Amalie P. Laursen, Jesper Simonsen, Jens Plum Frandsen, Harikrishnan Vijayan, Mogens Christensen^*

^*Corresponding author for this work

Research output: Contribution to journal/Conference contribution in journal/Contribution to newspaper › Journal article › Research › peer-review

Abstract

The topotactical transformation of goethite to hexaferrite was investigated using 2D synchrotron powder diffraction. The relation between structure, size, and texture in the synthesis was investigated using combined quantitative texture analysis and Rietveld refinements. Based on the refinements, the topotaxial relation from the precursor (goethite) through the intermediate (hematite) and to the product (hexaferrite) could be understood. In all three cases, the orientation of texture and smallest crystallite dimension is along the closest packed oxygen lattice, the c-axis. In the intermediary step where goethite is converted to hematite, a pseudomorphic transition is observed where particle shape is maintained along the a- and b-axis. Furthermore, the structural relation from the intermediate to the product was demonstrated to aid the understanding of the final step in the topotactical transition. Based on this study, we conclude that synthesis can be designed to promote texture in materials beyond magnets by appropriate choice and understanding of precursor structure and morphology.

Original language	English
Journal	Chemistry of Materials
Volume	36
Issue	4
Pages (from-to)	1919-1927
Number of pages	9
ISSN	0897-4756
DOIs	https://doi.org/10.1021/acs.chemmater.3c02616
Publication status	Published - 27 Feb 2024

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title = "Oriented Nanomagnets Originating from Topotactic and Pseudomorphic Reactions",

abstract = "The topotactical transformation of goethite to hexaferrite was investigated using 2D synchrotron powder diffraction. The relation between structure, size, and texture in the synthesis was investigated using combined quantitative texture analysis and Rietveld refinements. Based on the refinements, the topotaxial relation from the precursor (goethite) through the intermediate (hematite) and to the product (hexaferrite) could be understood. In all three cases, the orientation of texture and smallest crystallite dimension is along the closest packed oxygen lattice, the c-axis. In the intermediary step where goethite is converted to hematite, a pseudomorphic transition is observed where particle shape is maintained along the a- and b-axis. Furthermore, the structural relation from the intermediate to the product was demonstrated to aid the understanding of the final step in the topotactical transition. Based on this study, we conclude that synthesis can be designed to promote texture in materials beyond magnets by appropriate choice and understanding of precursor structure and morphology.",

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AU - Mørch, Mathias I.

AU - Thomas-Hunt, Jack

AU - Laursen, Amalie P.

AU - Simonsen, Jesper

AU - Frandsen, Jens Plum

AU - Vijayan, Harikrishnan

AU - Christensen, Mogens

PY - 2024/2/27

Y1 - 2024/2/27

N2 - The topotactical transformation of goethite to hexaferrite was investigated using 2D synchrotron powder diffraction. The relation between structure, size, and texture in the synthesis was investigated using combined quantitative texture analysis and Rietveld refinements. Based on the refinements, the topotaxial relation from the precursor (goethite) through the intermediate (hematite) and to the product (hexaferrite) could be understood. In all three cases, the orientation of texture and smallest crystallite dimension is along the closest packed oxygen lattice, the c-axis. In the intermediary step where goethite is converted to hematite, a pseudomorphic transition is observed where particle shape is maintained along the a- and b-axis. Furthermore, the structural relation from the intermediate to the product was demonstrated to aid the understanding of the final step in the topotactical transition. Based on this study, we conclude that synthesis can be designed to promote texture in materials beyond magnets by appropriate choice and understanding of precursor structure and morphology.

AB - The topotactical transformation of goethite to hexaferrite was investigated using 2D synchrotron powder diffraction. The relation between structure, size, and texture in the synthesis was investigated using combined quantitative texture analysis and Rietveld refinements. Based on the refinements, the topotaxial relation from the precursor (goethite) through the intermediate (hematite) and to the product (hexaferrite) could be understood. In all three cases, the orientation of texture and smallest crystallite dimension is along the closest packed oxygen lattice, the c-axis. In the intermediary step where goethite is converted to hematite, a pseudomorphic transition is observed where particle shape is maintained along the a- and b-axis. Furthermore, the structural relation from the intermediate to the product was demonstrated to aid the understanding of the final step in the topotactical transition. Based on this study, we conclude that synthesis can be designed to promote texture in materials beyond magnets by appropriate choice and understanding of precursor structure and morphology.

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VL - 36

SP - 1919

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JO - Chemistry of Materials

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ER -

Oriented Nanomagnets Originating from Topotactic and Pseudomorphic Reactions

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