A layered double hydroxide-derived exchange spring magnet array grown on graphene and its application as an ultrathin electromagnetic wave absorbing material

2019 ◽  
Vol 7 (39) ◽  
pp. 12270-12277 ◽  
Author(s):  
Xiaonan Zhao ◽  
Xiaoyu Nie ◽  
Ya Li ◽  
Yanhui Pu ◽  
Xin Sun ◽  
...  
Keyword(s):  
Electromagnetic Wave ◽  
Exchange Coupling ◽  
Coupling Effect ◽  
Soft Magnetic ◽  
Magnetic Phases ◽  
Graphene Composite ◽  
Exchange Spring ◽  
Doped Graphene ◽  
Absorbing Material ◽  
Double Hydroxide

An exchange spring magnet/N-doped graphene composite is synthesized as an ultrathin and highly efficient electromagnetic wave absorbing material utilizing the exchange coupling effect between hard/soft magnetic phases.

scholarly journals Nanocomposite permanent magnetic materials Nd-Fe-B type: The influence of nanocomposite on magnetic properties

2005 ◽  
Vol 41 (1) ◽  
pp. 95-102 ◽  
Author(s):  
Nadezda Talijan ◽  
Jasna Stajic-Trosic ◽  
Aleksandar Grujic ◽  
Vladan Cosovic ◽  
Vladimir Menushenkov ◽  
...  
Keyword(s):  
Magnetic Material ◽  
Heat Treatment ◽  
Magnetic Properties ◽  
Permanent Magnet ◽  
Exchange Coupling ◽  
Coupling Effect ◽  
Soft Magnetic ◽  
Magnetic Phases ◽  
New Type ◽  
Permanent Magnet Materials

The influence on the magnetic properties of nanocristalline ribbons and powders has character of microstructure, between others ? the grain size volume of hard and soft magnetic phases and their distribution. Magnetic properties of ribbons and powders depend mainly on their chemical composition and parameters of their heat treatment [1]. Technology of magnets from nanocristalline ribbon consists of the following process: preparing the Nd-Fe- B alloy, preparing the ribbon, powdering of the ribbon, heat treatment of the powder and finally preparing the magnets. Nanocomposite permanent magnet materials based on Nd-Fe- B alloy with Nd low content are a new type of permanent magnetic material. The microstructure of this nanocomposite permanent magnet is composed of a mixture of magnetically soft and hard phases which provide so called exchange coupling effect.

Study on the Nanostructure and Magnetic Properties of NdFeNbB Permanent Magnets

2010 ◽  
Vol 638-642 ◽  
pp. 1749-1754
Author(s):  
X.F. Wang ◽  
X.Y. Chen ◽  
Z.L. Jiang ◽  
Y. Chen ◽  
H.M. Chen
Keyword(s):  
Exchange Coupling ◽  
Permanent Magnets ◽  
Coupling Effect ◽  
Maximum Energy ◽  
Soft Magnetic ◽  
Magnetic Phases ◽  
Maximum Energy Product ◽  
Energy Product ◽  
High Maximum ◽  
Intrinsic Coercivity

Nd2Fe14B/-Fe nanocomposite permanent magnet contains the hard and soft magnetic phases, Nd2Fe14B and -Fe respectively. An exchange coupling effect exists between the two magnetic phases. The effect of alloying element Nb on its nanostructure and properties have been studied. Adding Nb to the alloy is effective to refine grains, a relatively small grain size causes a high intrinsic coercivity, remanence and therefore a high maximum energy product, (BH)max. MFM (Magnetic Force Microscope) was used to observe the magnetic micro-domain structure in the nanophase alloys. The length of the magnetic contrast shows a significant dependence on the microstructure and phase constitution, and the longer length is correspond with the larger exchange coupling effect between the soft and hard magnetic phases.

scholarly journals Nanocrystalline Nd-Fe-B Alloys for Polymer-Bonded Magnets Production

2012 ◽  
Vol 2012 ◽  
pp. 1-6
Author(s):  
Aleksandar Grujić ◽  
Vladan Ćosović ◽  
Aleksandar Ćosović ◽  
Jasna Stajić-Trošić
Keyword(s):  
Magnetic Properties ◽  
Exchange Coupling ◽  
Magnetic Phase ◽  
Coupling Effect ◽  
Maximum Energy ◽  
Soft Magnetic ◽  
Nanocomposite Structure ◽  
Maximum Energy Product ◽  
Energy Product ◽  
Composite Production

This study presents how different nanostructures of starting Nd-Fe-B particles have influence on magnetic properties of polymer-bonded Nd-Fe-B materials. Two types of nanocrystalline Nd-Fe-B alloys were used for polymer composite production by compression molding technique. The particles with low neodymium content (Nd-low) have nanocomposite structure with small exchange coupling effect between hard and soft magnetic phase. In other hand, practically monophase hard magnetic structure of Nd-Fe-B particles with stoichiometric neodymium content (Nd-stoich) shows improved magnetic properties. With increasing concentration of polymer matrix, the coercivity (Hcb), remanence (Br), and maximum energy product ((BH)max) decrease more prominenty for composites with stoichiometric Nd-Fe-B content.

NiZn double hydroxide nanosheet-anchored nitrogen-doped graphene enriched with the γ-NiOOH phase as an activity modulated water oxidation electrocatalyst

Nanoscale ◽  
2017 ◽  
Vol 9 (34) ◽  
pp. 12590-12600 ◽  
Author(s):  
Ayasha Nadeema ◽  
Vishal M. Dhavale ◽  
Sreekumar Kurungot
Keyword(s):  
Water Oxidation ◽  
Composite Catalyst ◽  
Facile Synthesis ◽  
Nitrogen Doped ◽  
Graphene Composite ◽  
Nitrogen Doped Graphene ◽  
Doped Graphene ◽  
Double Hydroxide

We report a facile synthesis of an open, thin layered and γ-NiOOH enriched NiZn-double hydroxide/nitrogen doped graphene composite catalyst exhibiting robust OER activity.

scholarly journals Magnetic Phase Coexistence and Hard–Soft Exchange Coupling in FePt Nanocomposite Magnets

Nanomaterials ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 1618
Author(s):  
O. Crisan ◽  
I. Dan ◽  
P. Palade ◽  
A. D. Crisan ◽  
A. Leca ◽  
...  
Keyword(s):  
Exchange Coupling ◽  
Hysteresis Loops ◽  
Squid Magnetometry ◽  
X Ray Diffraction ◽  
Soft Magnetic ◽  
Magnetic Phases ◽  
X Ray ◽  
Annealing Temperatures ◽  
Nanocomposite Magnets ◽  
Inflection Points

With the aim of demonstrating phase coexistence of two magnetic phases in an intermediate annealing regime and obtaining highly coercive FePt nanocomposite magnets, two alloys of slightly off-equiatomic composition of a binary Fe-Pt system were prepared by dynamic rotation switching and ball milling. The alloys, with a composition Fe53Pt47 and Fe55Pt45, were subsequently annealed at 400 °C and 550 °C and structurally and magnetically characterized by means of X-ray diffraction, 57Fe Mössbauer spectrometry and Superconducting Quantum Interference Device (SQUID) magnetometry measurements. Gradual disorder–order phase transformation and temperature-dependent evolution of the phase structure were monitored using X-ray diffraction of synchrotron radiation. It was shown that for annealing temperatures as low as 400 °C, a predominant, highly ordered L10 phase is formed in both alloys, coexisting with a cubic L12 soft magnetic FePt phase. The coexistence of the two phases is evidenced through all the investigating techniques that we employed. SQUID magnetometry hysteresis loops of samples annealed at 400 °C exhibit inflection points that witness the coexistence of the soft and hard magnetic phases and high values of coercivity and remanence are obtained. For the samples annealed at 500 °C, the hysteresis loops are continuous, without inflection points, witnessing complete exchange coupling of the hard and soft magnetic phases and further enhancement of the coercive field. Maximum energy products comparable with values of current permanent magnets are found for both samples for annealing temperatures as low as 500 °C. These findings demonstrate an interesting method to obtain rare earth-free permanent nanocomposite magnets with hard–soft exchange-coupled magnetic phases.

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