Magnetic Nanomaterials

Fundamentals, Synthesis and Applications

Yanglong Hou, David J. Sellmyer

• Publisher: Wiley
• Year: 2017
• Print ISBN: 9783527341344
• eBook ISBN: 9783527803262
• Edition: 1
• Topic: Biological Sciences
• Subtopic: Biotechnology
• Index: Biological Sciences

Timely and comprehensive, this book presents recent advances in magnetic nanomaterials research, covering the latest developments, including the design and preparation of magnetic nanoparticles, their physical and chemical properties as well as their applications in different fields, including biomedicine, magnetic energy storage, wave-absorbing and water remediation.
By allowing researchers to get to the forefront developments related to magnetic nanomaterials in various disciplines, this is invaluable reading for the nano, magnetic, energy, medical, and environmental communities.

Part One
Fundamentals

1
Overview of Magnetic Nanomaterials

Ziyu Yang,¹ Shuang Qiao,¹ Shouheng Sun,² and Yanglong Hou¹

¹Peking University, College of Engineering, Department of Materials Science and Engineering, 5 Yi He Yuan Road, Beijing 100871, China

²Brown University, Department of Chemistry, 324 Brook Street, Providence, RI 02912, USA

1.1 Introduction

Magnetic nanomaterials have long been investigated due to their scientific and technological importance in many areas, such as magnetic data storage, magnetic fluids, catalysis, biomedicine, magnetic resonance imaging, hyperthermia, magnetic refrigeration, and environmental remediation [1–11]. The unique effects induced by the nanoscale distinguish the magnetism of the nanomaterials from their bulk counterparts. When a material is cut into smaller dimensions, the number of magnetic domains included in the material is decreased and magnetic coercivity is increased. When the size reaches a critical value, the material can only support a single magnetic domain and magnetic behavior of this single-domain material depends mostly on magnetization rotation. Depending on the magnetic characteristics, the single domain size of a material can be in tens, hundreds, or even thousands of nanometers. When the material dimension continues to shrink below the single domain size, surface atoms and temperature start to affect magnetic behaviors drastically and the material can become superparamagnetic at room temperature in which state it can be magnetized as a ferromagnetic material, but its magnetization direction is randomized by thermal agitation, showing zero remanent magnetization and no coercivity.

The key issues related to magnetic nanomaterials are in the synthesis with the desired size, shape, and structure controls. Due to the large surface area, surface energy, and magnetic dipolar interactions, magnetic nanomaterials should also be stabilized by a layer of organic or inorganic matrix. The coating chemistry developed further allows proper functionalization of these nanomaterials for varied applications. The controlled synthesis and coating for stabilization can now be realized from organic-phase synthesis protocols [12,13].

In this chapter, we summarize some widely explored magnetic nanomaterials of (i) metals and alloys, especially single metal M (M = Fe/Co/Ni) and their related alloys, such as MN (N = noble metal) and alloys of M₁M₂ (M₁, M₂ = Fe, Co, Ni); (ii) Fe/Co/Ni/Mn oxides; (iii) metal carbides and nitrides; (iv) rare earth (RE)-based permanent magnets, specially RE-Fe (Co), RE-Fe (Co)-B, and RE-Fe (Co)-C/N magnets. In addition to the synthesis, we also review some of the common methods used to characterize these magnetic nanomaterials to better understand their phases, morphologies, micromagnetic structures, and bonding structures. We focus on the tools of X-ray magnetic circular dichroism (XMCD) spectroscopy, Lorentz transmission electron microscope and Mössbauer spectroscopy, magnetic extended X-ray absorption fine structure (MEXAFS), magnetic force microscopy (MFM), and superconducting quantum interference device (SQUID).

1.1.1 Typical Magnetic Nanomaterials

1.1.1.1 Magnetic Nanomaterials of Metal (Fe, Co, and Ni)

Fe, Co, and Ni are three common ferromagnetic elements that serve as structural backbones for tons of magnetic ...

Table of contents

• Cover
• Title Page
• Copyright
• List of Contributors
• Preface
• Part One: Fundamentals
• Part Two: Synthesis
• Part Three: Applications
• Index
• End User License Agreement