Nanoscopic oxygen control of functional oxide nanoparticles by electro-chemical route at ambient temperature

TL;DR

Researchers developed a method to control oxygen levels in oxide nanoparticles at room temperature without changing their size, affecting their magnetic properties.

Contribution

A novel electrochemical method to adjust oxygen stoichiometry in nanoparticles at ambient temperature without altering their size.

Findings

Electrochemical oxidation changes the oxygen stoichiometry without altering nanoparticle size.

Oxygen incorporation affects unit cell volume, lattice constants, and magnetic properties.

Surface layer oxygen changes influence magnetization and coercive field.

Abstract

La0.67Ca0.33MnOδ nanoparticles of approximate size ∼ 4 nm have been prepared by the chemical solution deposition method to investigate effect of oxygen stoichiometry in the nanoparticles without changing their sizes. Electrochemical oxidation method has been used to change the oxygen stoichiometry \documentclass[12pt]{minimal}
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\begin{document}$$\delta$$\end{document}δ at room temperature, which unlike conventional methods to change oxygen stoichiometry by heating in controlled ambience, does not lead to any significant change in size. This has allowed us to investigate the effects of stoichiometry variations in the nanoparticles with no change in size. The unit cell volume, lattice constants and orthorhombic strains of the as prepared sample (with \documentclass[12pt]{minimal}
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\begin{document}$$\delta$$\end{document}δ = 2.74) are changed by incorporation of oxygen by electrochemical oxidation which in turns affects the magnetic properties. In addition, oxidation leads to change in oxygen stoichiometry of the magnetically “dead” surface layer on the nanoparticles which also affects their magnetization and coercive field.

The online version contains supplementary material available at 10.1186/s11671-024-03969-y.

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