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

A new precursor of molecule-based magnetic systems, [Fe(H2opba-i)(dmso)2]Cl (1), with opba = ortho-phenylenebis(oxamato) in an iminoalcohol tautomeric form, was obtained as a product from the reaction between H4opba and FeCl3. Data from elemental analysis, IR and Mossbauer spectroscopies and magnetic measurements indicate that this precursor is composed of a mixture of trans (83%) and cis (17%) isomers. The cMT value at 298K (2.1 emu K mol-1) corresponds to FeIII with spin state (S) between 3/2 and 5/2. Theoretical calculations (PBE/DZVP2) of trans- and cis-[Fe(H2opba-i)(dmso)2 ]+ show that both isomers have spin S = 1/2 in the ground state and S = 3/2 for the trans and S = 5/2 for the cis in the first excited state. The combination of these results leads to cMT values of 0.375 and 2.3 emu K mol-1, at low and high temperature respectively, which are in accordance with the experimental data for 1.

/pdf/synthesis-and-density-functional-calculations-of-the-new-3pzdcc65rz.pdf

Synthesis and density functional calculations of the new molecule-based magnet precursor [Fe(H2opba-i)(dmso)2]Cl

Iron Oxide Nanoparticles in a Dynamic Flux: Implications for Magnetic Hyperthermia-Controlled Fluid Viscosity

The effect of particle size distribution on the magnetic properties of nanocrystalline Fe/sub 86/Zr/sub 7/Cu/sub 1/B/sub 6/ samples is studied in detail. The analysis applies a realistic particle size distribution, obtained from transmission electron microscopy images, to the recently developed extended Random Anisotropy Model. The effect of a broad size distribution is found to be more relevant when the tail of the distribution is larger than 20 nm.

Influence of particle size distribution on magnetic properties of nanocrystalline soft magnetic Fe/sub 86/Zr/sub 7/Cu/sub 1/B/sub 6/

Apresenta o Programa de Formacao Interdisciplinar Superior (ProFIS), curso de nivel superior implantado na Universidade Estadual de Campinas (Unicamp) em 2011. Primeiramente, sao citados os objetivos e as diretrizes que nortearam a criacao do curso – aumento do ingresso de alunos de escolas publicas na universidade e a adocao de um programa de formacao geral – e, em seguida, descritos, em linhas gerais, o novo curso, seu curriculo e o processo de transferencia dos alunos concluintes do ProFIS para os cursos de graduacao da Unicamp. Conclui apresentando uma analise sobre o criterio de selecao adotado, bem como alguns dados estatisticos que revelam que os propositos de inclusao social foram plenamente alcancados pela primeira turma matriculada no programa.

/pdf/programa-de-formacao-interdisciplinar-superior-um-novo-2hdx2i4p4a.pdf

Marcelo Knobel

Papers

Synthesis and density functional calculations of the new molecule-based magnet precursor [Fe(H2opba-i)(dmso)2]Cl

Iron Oxide Nanoparticles in a Dynamic Flux: Implications for Magnetic Hyperthermia-Controlled Fluid Viscosity

Influence of particle size distribution on magnetic properties of nanocrystalline soft magnetic Fe/sub 86/Zr/sub 7/Cu/sub 1/B/sub 6/

Programa de Formação Interdisciplinar Superior: um novo caminho para a educação superior

Study of anhysteretic magnetization loops of Co0.35(SiO2)0.65 granular film