Effects of crystallite size on the structure and magnetism of ferrihydrite

Xiaoming Wang,Wenqian Xu,Jing Zhang,Luuk K Koopal,Qingsong Liu,Fan Liu,Wei Li,Xionghan Feng,Mengqiang Zhu,Donald L Sparks

doi:10.1039/c5en00191a

Abstract

The structure and magnetic properties of nano-sized (1.6 to 4.4 nm) ferrihydrite samples are systematically investigated through a combination of X-ray diffraction (XRD), X-ray pair distribution function (PDF), X-ray absorption spectroscopy (XAS) and magnetic analyses.

Highlights

Metastable nano-crystalline ferrihydrites are ubiquitous in environmental systems including surface water, soils, sediments, living organisms and even extraterrestrial substances.[1]
The detailed synthesis procedures have been described by Wang et al.[13] and the samples were labeled as 2LFh_1, 5LFh_2, 5LFh_3 and 6LFh_4, in which the first number indicates the number of diffraction lines in the X-ray diffraction (XRD) pattern, while the last number indicates the increasing order of crystallite size.[13]
From 2LFh_1 to 6LFh_4, the full width at half maximum (FWHM) of the peaks gradually decreases, which implies that the crystallite size gradually increases

Summary

Introduction

Metastable nano-crystalline ferrihydrites are ubiquitous in environmental systems including surface water, soils, sediments, living organisms and even extraterrestrial substances.[1]. For particles larger than 8 nm, the ferrihydrite thermodynamic stability sharply drops with increasing particle size, leading to the formation of nano-goethite and nano-hematite.[19,20]

Methods

Results

Discussion

Conclusion