Structure and magnetic properties of a nickel(ii) complex of a tridentate verdazyl radical: strong ferromagnetic metal-radical exchange coupling

2000 ◽  
pp. 2141-2142 ◽  
Author(s):  
Tosha M. Barclay ◽  
Robin G. Hicks ◽  
Martin T. Lemaire ◽  
Laurence K. Thompson
2019 ◽  
Vol 48 (37) ◽  
pp. 14189-14200 ◽  
Author(s):  
Rajendar Nasani ◽  
Thulaseedharan Nair Sailaja Sidharth ◽  
Subhadip Roy ◽  
Arpan Mondal ◽  
Jeremy M. Rawson ◽  
...  

A new Blatter radical and its Zn(ii) (1), Ni(ii) (2) and Co(ii) (3) complexes were isolated. Complex 1 exhibited radical⋯radical antiferromagnetic exchange coupling, whereas complexes 2 and 3 showed ferromagnetic metal–radical coupling.


Author(s):  
Junjie Xu ◽  
Kai Zhu ◽  
Song Gao ◽  
Yanglong Hou

The routes for the optimization of the magnetic properties of rare earth permanent magnetic nanostructures are discussed, i.e. the control of microstructure, such as size and shape as well as the exchange-coupling interactions.


1999 ◽  
Vol 577 ◽  
Author(s):  
Q. Chen ◽  
B. M. Ma ◽  
B. Lu ◽  
M. Q. Huang ◽  
D. E. Laughlin

ABSTRACTThe phase transformation and the exchange coupling in (Ndo095Lao005)9.5FebaICOsNb 2BI05 have been investigated. Nanocomposites were obtained by treating amorphous precursors at temperatures ranging from 650TC to 9500C for 10 minutes. The magnetic properties were characterized via the vibrating sample magnetometer (VSM). X-ray diffraction (XRD), thermomagnetic analysis (TMA), and transmission electron microscopy (TEM) were used to perform phase identification, measure grain size, and analyze phase distribution. The strength of the exchange coupling between the magnetically hard and soft phases in the corresponding nanocomposite was analyzed via the AM-versus-H plot. It was found that the remanence (Br), coercivity (Hci), and maximum energy product (BHmax) obtained were affected by the magnetic phases present as well as the grain size of constituent phases and their distribution. The optimal magnetic performance, BHm, occurred between 700°C to 750°C, where the crystallization has completed without excessive grain growth. TMA and TEM indicated that the system was composed of three phases at this point, Nd2(Fe Co) 14B, ca-Fe, and Fe3B. The exchange coupling interaction among these phases was consistently described via the AM-versus-H plot up to 750°C. The Br, Hci, and BHmax degraded severely when the thermal treatment temperature increased from 750°C. This degradation may be attributed to the grain growth of the main phases, from 45 to 68nm, and the development of precipitates, which grew from 5nm at 750°C to 12nm at 850°C. Moreover, the amount of the precipitates was found to increase with the thermal treatment temperatures. The precipitates, presumably borides, may cause a decrease in the amount of the a-Fe and Fe 3B and result in a redistribution of the Co in the nanocomposites. The increase of the Co content in the Nd 2(Fe Co) 14B may explain the increase of its Curie temperature with the thermal treatment temperatures. In this paper, we examine the impacts of these factors on the magnetic properties of (Ndo 95Lao 05)9 5FebaICosNb2B10.5 nanocomposite.


2021 ◽  
Author(s):  
Christian Dirk Buch ◽  
Steen Hansen ◽  
Dmitri Mitcov ◽  
Camilla Mia Tram ◽  
Gary Nichol ◽  
...  

Heterolanthanide complexes are difficult to synthesize owing to the similar chemistry of the lanthanide ions. Conse-quently, very few purely heterolanthanide complexes have been synthesized. This is despite the fact that such complexes hold inter-esting optical and magnetic properties. To fine-tune these properties, it is important that one can choose complexes with any given combination of lanthanides. Herein we report a synthetic procedure which yields pure heterodinuclear lanthanide cryptates LnLn*LX3 (X = NO3- or OTf-) based on the cryptand H3L = N[(CH2)2N=CH-R-CH=N-(CH2)2]3N (R = m-C6H2OH-2-Me-5). In the synthesis the choice of counter ion and solvent prove crucial in controlling the Ln-Ln*composition. Choosing the optimal solvent and counter ion affords pure heterodinuclear complexes with any given combination of Gd(III)-Lu(III) including Y(III). To demon-strate the versatility of the synthesis all dinuclear combinations of Y(III), Gd(III), Yb(III) and Lu(III) were synthesized resulting in 10 novel complexes of the form LnLn*L(OTf)3 with LnLn* = YbGd 1, YbY 2, YbLu 3, YbYb 4, LuGd 5, LuY 6, LuLu 7, YGd 8, YY 9 and GdGd 10. Through the use of 1H, 13C NMR and mass spectrometry the heterodinuclear nature of YbGd, YbY, YbLu, LuGd, LuY and YGd was confirmed. Crystal structures of LnLn*L(NO3)3 reveal short Ln-Ln distances of ~3.5 Å. Using SQUID magnetometry the exchange coupling between the lanthanide ions was found to be anti-ferromagnetic for GdGd and YbYb while ferromagnetic for YbGd.


2006 ◽  
Vol 102 (2) ◽  
pp. 149-156 ◽  
Author(s):  
I. D. Lobov ◽  
V. M. Maevskii ◽  
M. M. Kirillova ◽  
A. V. Korolev ◽  
F. A. Pudonin

2002 ◽  
Vol 82 (1) ◽  
pp. 85-104 ◽  
Author(s):  
A. Vernes ◽  
P. Weinberger ◽  
C. Blaas ◽  
P. Mohn ◽  
L. Szunyogh ◽  
...  

2000 ◽  
Vol 648 ◽  
Author(s):  
B. Schirmer ◽  
X. Liu ◽  
M. Wuttig

AbstractUltrathin iron films grown on Cu(100) have been found to exhibit a rich variety of structural and magnetic phases. In the present work, Fe/Ni bilayers have been prepared by molecular beam epitaxy to explore novel magnetic phenomena introduced by the ferromagnetic (FM) Ni underlayer. Unusual properties have been observed by measuring the temperature dependent magnetic properties. For 5.3 ML Fe on 7 ML Ni, a temperature dependent exchange coupling in the Fe film has been observed between the FM surface layer and FM interface layer.


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