Core/Shell Nanoparticles: Classes, Properties, Synthesis Mechanisms, Characterization, and Applications

In this chapter, we will restrict our attention to the ferrites and a few other closely related materials. The great interest in ferrites stems from their unique combination of a spontaneous magnetization and a high electrical resistivity. The observed magnetization results from the difference in the magnetizations of two non-equivalent sub-lattices of the magnetic ions in the crystal structure. Materials of this type should strictly be designated as “ferrimagnetic” and in some respects are more closely related to anti-ferromagnetic substances than they are to ferromagnetics in which the magnetization results from the parallel alignment of all the magnetic moments present. We shall not adhere to this special nomenclature except to emphasize effects, which are due to the existence of the sub-lattices.

Ferromagnetic materials

http://files.janapv.webnode.cz/200000097-8a03f8afdf/ex_bias_nano.pdf

Exchange bias in nanostructures

We developed two-step solution-phase reactions to form hybrid materials of Mn3O4 nanoparticles on reduced graphene oxide (RGO) sheets for lithium ion battery applications. Mn3O4 nanoparticles grown selectively on RGO sheets over free particle growth in solution allowed for the electrically insulating Mn3O4 nanoparticles wired up to a current collector through the underlying conducting graphene network. The Mn3O4 nanoparticles formed on RGO show a high specific capacity up to ~900mAh/g near its theoretical capacity with good rate capability and cycling stability, owing to the intimate interactions between the graphene substrates and the Mn3O4 nanoparticles grown atop. The Mn3O4/RGO hybrid could be a promising candidate material for high-capacity, low-cost, and environmentally friendly anode for lithium ion batteries. Our growth-on-graphene approach should offer a new technique for design and synthesis of battery electrodes based on highly insulating materials.

Mn3O4-Graphene Hybrid as a High Capacity Anode Material for Lithium Ion Batteries

https://www.andrew.cmu.edu/user/dl0p/laughlin/pdf/PMS.pdf

Amorphous and nanocrystalline materials for applications as soft magnets

We report on the investigation of the exchange bias effect in Fe layers on EuTe(111), an antiferromagnetic semiconductor. For this ferromagnet (FM)/semiconducting antiferromagnet (AFM) exchange bias system, we have found positive and negative exchange bias effect (EB). Fresh samples exhibit positive EB, independently of the applied cooling field, indicating antiferromagnetic coupling between the FM and the AFM layers at the Fe/EuTe(111) interface. The change in EB with time, from positive EB for fresh samples to negative EB after short time,is attributed to aging effects at the Fe/EuTe interface.

/pdf/exchange-bias-in-fe-eute-111-bilayers-1pukdn9dyn.pdf

Exchange bias in Fe/EuTe(111) bilayers

On the Use of Joule Heating Techniques to Produce Nanostructured Magnetic Materials from Melt-Spun Ribbons

Microstructure and Magnetic Properties of Co Films on Si: Thickness and Roughness Dependence

/pdf/brazil-s-student-mobility-initiative-13uegvqmf4.pdf

Marcelo Knobel

Papers

Exchange bias in Fe/EuTe(111) bilayers

On the Use of Joule Heating Techniques to Produce Nanostructured Magnetic Materials from Melt-Spun Ribbons

Microstructure and Magnetic Properties of Co Films on Si: Thickness and Roughness Dependence

Brazil’s Student Mobility Initiative

Role of Soft Magnetic Properties on the Sensitivity of the Giant Magneto-Impedance Effect