19192-71-3Relevant articles and documents
Size and doping effects on the improvement of the low-temperature magnetic properties of magnetically aligned cobalt ferrite nanoparticles
Knobel, Marcelo,Moscoso-Londo?o, Oscar,Muraca, Diego,Rivas-Rojas, Patricia C.,Socolovsky, Leandro M.,Tancredi, Pablo
, (2021/11/01)
The macroscopic magnetic behavior of nanoparticulated systems is the result of several contributions, ranging from the intrinsic structural properties of the nanoparticles to their spatial arrangement within the material. Unravelling and understanding these influences is an important task to produce nano-systems with improved properties for specific technological applications. In this work we study how the magnetic behavior of a set of magnetically hard nanoparticles can be improved by the modification of the sample arrangement (either randomly or magnetically oriented) and the nature of the enclosing matrices. At first, we employed a hot-injection, continuous growth strategy to synthesize non-stoichiometric cobalt ferrite (CoxFe3?xO4) nanoparticles. We prepared five batches of hydrophobic, oleate-coated samples, with mean diameters of 8 nm, 12 nm, 16 nm and variable Co-to-Fe proportions. The structural characterization confirms that the nanoparticles have a spinel-type monocrystalline structure and that the Co and Fe ions are homogenously distributed within the system. The magnetic properties of the nanoparticles were measured by DC magnetometry, and we found that the strategy used in this work to create a system of magnetically oriented nanoparticles can lead to a significant remanence and coercive field enhancement at low temperatures when compared with randomly oriented and fixed systems. The modification of the magnetic properties was detected in the five batches of samples, but the strength of the enhancement depends on both size and composition of the nanoparticles. Indeed, for the “hardest” samples the coercive field of the magnetically oriented systems reached values of around 30 kOe (3 T), which represents a 50% increase regarding the randomly oriented system and are among the highest reported to date for a set of Fe and Co oxide nanoparticles.
Rapid and large-scale synthesis of bare Co3O4 porous nanostructures from an oleate precursor as superior Li-ion anodes with long-cycle lives
Ge, Danhua,Wu, Junjie,Qu, Genlong,Deng, Yaoyao,Geng, Hongbo,Zheng, Junwei,Pan, Yue,Gu, Hongwei
, p. 13509 - 13513 (2016/09/04)
In this study, we describe a rapid and environmentally friendly synthesis of bare Co3O4 nanocrystals derived from Co(ii) oleate complexes by calcination treatment. When directly used as anode materials for lithium-ion batteries (LIBs), the as-prepared nanocrystals could deliver a high reversible capacity of 980 mA h g-1 after 250 cycles at a current density of 100 mA g-1 and excellent cycling performance, which may be beneficial to promote the further development of the next generation of lithium ion batteries. The synthetic route can offer great advantages for the flash preparation of other metal oxide nanocrystals for energy storage application.
Nanoparticle-sulphur "inverse vulcanisation" polymer composites
Bear, Joseph C.,Peveler, William J.,McNaughter, Paul D.,Parkin, Ivan P.,O'Brien, Paul,Dunnill, Charles W.
supporting information, p. 10467 - 10470 (2015/06/25)
Composites of sulphur polymers with nanoparticles such as PbS, with tunable optical properties are reported. A hydrothermal route incorporating pre-formed nanoparticles was used, and their physical and chemical properties evaluated by transmission and scanning electron microscopy, thermogravimetric and elemental analyses. These polymers are easily synthesised from an industrial waste material, elemental sulphur, can be cast into virtually any form and as such represent a new class of materials designed for a responsible energy future.
