# Optical, luminescence and magnetic properties of braunite‒rhodonite nanocomposites synthesized by green aqueous sol‒gel route

## TL;DR

Researchers made nanocomposites from braunite and rhodonite using a green method and found they have useful optical and magnetic properties for electronics and biomedical uses.

## Contribution

A green sol-gel method was used to synthesize braunite-rhodonite nanocomposites with tunable optical and magnetic properties.

## Key findings

- Nanocomposites showed green, yellow, and red fluorescence emissions.
- Optical band gap energy increased with higher MnSiO3-content.
- Nanocomposites exhibited antiferromagnetic properties with increased magnetization at higher MnSiO3-content.

## Abstract

Braunite (Mn7SiO12)‒rhodonite (MnSiO3) nanocomposites have been synthesized utilizing a green aqueous citrate sol‒gel route. The influence of heat-treatment temperature on the structure and properties of these nanocomposites was investigated. X-ray diffraction and high resolution transmission electron microscopy analyses demonstrated that well-crystallized nanoparticles, having average sizes in the range of 18‒42 nm, were produced. MnSiO3-content increased in the nanocomposites with increasing calcination temperature from 600 to 900 °C. Optical, photoluminescence and magnetic properties were determined. Ultraviolet–visible-near infrared diffuse reflectance spectra were used, applying Kubelka–Munk function, for optical absorbance calculation and determination of the band gap energy (Eg). Optical absorption spectra exhibited bands at 415‒438 nm originated from Mn2+ ions, and other bands at 550 and 599 nm due to absorption of Mn3+ ions. Eg was found to increase with increasing MnSiO3-content in the nanocomposites. The obtained nanocomposites gave green fluorescence emissions at 525‒565 nm, a yellow emission at 584 nm and red emissions at 619 nm. All the synthesized nanocomposites exhibited antiferromagnetic properties in which the paramagnetic contribution and magnetization increased as the MnSiO3-content increased. The present nanocomposites are promising candidates for application as light emitting diodes as well as magnetoelectronic materials which are used in biomedical applications.