Hydrothermal synthesis of Al-doped magnetite nanoflakes and the effect of aspect ratio on their magnetic properties

Abstract

The current study is an effort to use a hydrothermal process to create flake-like iron oxide particles with various aspect ratios. In the initial stage, various morphologies of hematite nanoparticles were produced, which were subsequently thermally reduced into the magnetite phase using C2H2 gas as the reduction atmosphere. Tuning the aluminum cation concentration in the initial hydrothermal batch composition resulted in truncated hexagonal bipyramid (THB) shaped particles and pseudo-hexagonal flakes with varying diameters and thicknesses. The likely mechanisms for morphological evolution were addressed. The studies utilizing FESEM images indicated that particles with aspect ratios ranging from 1.1 to 20.3 were obtained. Because hematite nanoparticles are known to be weakly ferromagnetic, we concentrated on investigating changes in magnetic characteristics caused by aspect ratio alterations in magnetite nanoparticles. The alternating gradient force magnetometery technique was used to measure the magnetic characteristics at room temperature. Maximum magnetizations of 30–99 emu/g were recorded at a maximum field strength of 9 kOe, which was very sensitive to the aspect ratio. The successful hydrothermal synthesis of magnetite flake particles and control of their magnetic properties by aspect ratio changes might be a promising result that could be extended to other physical and chemical application fields.