Lattice Strain of Zn-Mn Mixed Ferrite Nanocrystals in a Core-Shell Morpho-Chemical Structure

F H Martins,F.L.O Paula,V Pilati,R Perzynski,R.C Gomes,J Depeyrot

doi:10.1590/1980-5373-mr-2021-0596

Abstract

In this work, the crystalline structure, chemical composition, size, and morphology of core@shell nanoparticles based on Zn-Mn ferrite nanocrystals were investigated. These materials have been proposed as promising candidates for multifunctional applications in biomedicine, catalysis, environmental remediation, among others. Those properties were probed by using several experimental techniques such as Synchrotron X-Ray Diffraction, Energy-Dispersive X-ray Spectroscopy, Transmission Electron Microscopy and Selected Area Electron Diffraction. Results show that all synthesized nanoparticles present a single crystalline spinel phase without the appearance of undesirable byproducts. The nanoparticles present a non-stoichiometric Zn-Mn ferrite core, due to a Fe enrichment and a Zn loss with respect to the synthesis medium. The surface treatment of the nanoparticles induces a greater iron enrichment, which occurs at the nanoparticles surface without changing the crystalline structure. Finally, modifications in lattice parameters and strain suggest a contribution of the Mn2+ cations, mainly related to their easy oxidation in the synthesis route, which increases the structural vacancies of Mn-richer ferrites.

Highlights

Nanoparticles (NPs) based on iron-oxides nanocrystals have been probed as multifunctional tools for several applications in the biomedical field[1,2,3,4,5], agriculture[6,7,8], environmental remediation[9,10,11,12], catalysis[13,14,15], among others
These applications are conceived through the design of physical properties, which can be achieved by performing adjustments on the chemical composition of the ferrites, modifying physical properties such as the size of the nanocrystals, crystalline structure, and cation distribution
A Zn2+ fraction being replaced by Fe3+ cations and the oxidation of Mn2+ cations in Mn3+ or Mn4+, which commonly occurs during synthesis in alkaline medium due to the high concentration of oxygen in the medium[59,60,61,62,63], both contribute to the ferrite oxidation

Summary

Introduction

Nanoparticles (NPs) based on iron-oxides nanocrystals have been probed as multifunctional tools for several applications in the biomedical field[1,2,3,4,5], agriculture[6,7,8], environmental remediation[9,10,11,12], catalysis[13,14,15], among others These applications are conceived through the design of physical properties, which can be achieved by performing adjustments on the chemical composition of the ferrites, modifying physical properties such as the size of the nanocrystals, crystalline structure, and cation distribution. The introduction of non-magnetic Zn2+ ions into the crystalline structure of Mn

Methods

Results

Conclusion