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

Hydrogen energy, economy and storage: Review and recommendation

Recovery and reuse of expensive catalysts after catalytic reactions are important factors for sustainable process management. The aim of this Review is to highlight the progress in the formation and catalytic applications of magnetic nanoparticles and magnetic nanocomposites. Directed functionalization of the surfaces of nanosized magnetic materials is an elegant way to bridge the gap between heterogeneous and homogeneous catalysis. The introduction of magnetic nanoparticles in a variety of solid matrices allows the combination of well-known procedures for catalyst heterogenization with techniques for magnetic separation.

Magnetically Separable Nanocatalysts: Bridges between Homogeneous and Heterogeneous Catalysis

https://hal.archives-ouvertes.fr/hal-00864984/document

MXene: a promising transition metal carbide anode for lithium-ion batteries

The aim of this review article on recent developments of mechanochemistry (nowadays established as a part of chemistry) is to provide a comprehensive overview of advances achieved in the field of atomistic processes, phase transformations, simple and multicomponent nanosystems and peculiarities of mechanochemical reactions. Industrial aspects with successful penetration into fields like materials engineering, heterogeneous catalysis and extractive metallurgy are also reviewed. The hallmarks of mechanochemistry include influencing reactivity of solids by the presence of solid-state defects, interphases and relaxation phenomena, enabling processes to take place under non-equilibrium conditions, creating a well-crystallized core of nanoparticles with disordered near-surface shell regions and performing simple dry time-convenient one-step syntheses. Underlying these hallmarks are technological consequences like preparing new nanomaterials with the desired properties or producing these materials in a reproducible way with high yield and under simple and easy operating conditions. The last but not least hallmark is enabling work under environmentally friendly and essentially waste-free conditions (822 references).

/pdf/hallmarks-of-mechanochemistry-from-nanoparticles-to-5cyjx2wiue.pdf

Hallmarks of mechanochemistry: From nanoparticles to technology

Magnetic properties of CoFe2O4 ferrite doped with rare earth ion

Gold nanoparticles-mesoporous silica composite (GNPs-MPS) is developed as a novel enzyme immobilization matrix for biosensor construction The mesoporous silica SBA-15 is chosen and the GNPs-SBA-15 is formed from AuCl4− adsorbed H2N-SBA-15 by NaBH4 reduction The synthesis process of the composite is monitored by UV–vis spectroscopy and the product is characterized by transmission electron microscopy (TEM) measurement An amperometric glucose biosensor is built by immobilizing IO4−-oxidized-glucose oxidase (IO4−-oxidized-GOD) on GNPs-MPS modified Au electrode using 2-aminoethanethiol as a cross-linker Cyclic voltammetry (CV) and amperometry are employed to investigate the catalytic behavior of the biosensor to the oxidation of glucose As a result, the biosensor exhibits an excellent bioelectrocatalytic response to glucose with a fast response time less than 7 s, a broad linear range of 002–14 mM, high sensitivity of 61 μA mM−1 cm−2, as well as good long-term stability and reproducibility These performances could be ascribed to the GNPs-MPS's features, such as excellent conductivity, large surface area and good biocompatibility

Gold nanoparticles-mesoporous silica composite used as an enzyme immobilization matrix for amperometric glucose biosensor construction

Lithium ferrite nanocrystallites ranging from several nanometres to several hundreds of nanometres in size have been prepared by the polyethylene glycol gel method. These nanocrystallites were identified as pure lithium ferrite by x-ray diffraction analysis. Their magnetization and de-magnetization were measured by using a vibrating sample magnetometer at different temperatures. The specific saturation magnetization and the coercivities change with the diameter of these nanocrystallites and with temperature. The effective magnetic anisotropy constants of these samples were deduced by using the law of approach to saturation. It is found that the value of a lithium ferrite nanocrystallite of diameter 9.1 nm is about ten times greater than the magnetocrystalline anisotropy constant of bulk lithium ferrite. The coercivities of these nanocrystallites at different temperatures were calculated by using the mixed coercivity model. The calculated coercivity results are consistent with the experimental ones.

https://iopscience.iop.org/article/10.1088/0022-3727/29/10/008/pdf

A study on the coercivity and the magnetic anisotropy of the lithium ferrite nanocrystallite

Effect of Eu,Tb codoping on the luminescent properties of Y2O3 nanorods

Nanocrystalline Fe/Fe3C composites have been fabricated by an efficient solid-state synthesis route. In this reaction process, we choose the organic compound melamine as the carbon source and hydrothermally prepared nanocrystalline Fe/Fe3O4 composite as metal precursor. X-ray diffraction, transmission electron microscopy, high-resolution transmission electron microscopy and vibrating sample magnetometry have been used to characterize the composites. The experimental results show that changing reaction temperature, reaction time and the amount of melamine allows control over the composition of Fe/Fe3C composites, particle morphology and magnetic properties. The possible formation mechanisms of as-prepared nanostructures with different morphologies are discussed briefly. Magnetization measurements indicate that the composites display ferromagnetic properties at room temperature.

Hua Yang

Papers

Magnetic properties of CoFe2O4 ferrite doped with rare earth ion

Gold nanoparticles-mesoporous silica composite used as an enzyme immobilization matrix for amperometric glucose biosensor construction

A study on the coercivity and the magnetic anisotropy of the lithium ferrite nanocrystallite

Effect of Eu,Tb codoping on the luminescent properties of Y2O3 nanorods

Magnetic properties of nanocrystalline Fe/Fe3C composites