scholarly journals Magnetism of FePt Nanoclusters in Polyimide

2015 ◽  
Vol 2015 ◽  
pp. 1-10 ◽  
Author(s):  
Mircea Chipara ◽  
Tom George ◽  
Yingfan Xu ◽  
Ralph Skomski ◽  
Lanping Yue ◽  
...  
Keyword(s):  
Magnetic Anisotropy ◽  
Thermal Annealing ◽  
Blocking Temperature ◽  
Fept Nanoparticles ◽  
Hybrid Films ◽  
Polyimide Films ◽  
X Ray ◽  
X Ray Scattering ◽  
Paramagnetic Impurities ◽  
Spin Resonance

FePt nanoclusters have been implanted onto polyimide films and subjected to thermal annealing in order to obtain a special magnetic phase (L10) dispersed within the polymer. SQUID measurements quantified the magnetic features of the as-prepared and annealed hybrid films. As-implanted FePt nanoparticles in polyimide films exhibited a blocking temperature of 70 ± 5 K. Thermal annealing in zero and 10 kOe applied magnetic field increased the magnetic anisotropy and coercivity of the samples. Wide Angle X-Ray Scattering confirmed the presence of FePt and L10phase. All samples (as deposited and annealed) exhibited electron spin resonance spectra consisting of two overlapping lines. The broad line was a ferromagnetic resonance originating from FePt nanoparticles. Its angular dependence indicated the magnetic anisotropy of FePt nanoparticles. SEM micrographs suggest a negligible coalescence of FePt nanoparticles, supporting that the enhancement of the magnetic properties is a consequence of the improvement of the L10structure. The narrow ESR line was assigned to nonmagnetic (paramagnetic) impurities within the samples consistent with graphite-like structures generated by the local degradation of the polymer during implantation and annealing. Raman spectroscopy confirmed the formation of graphitic structures in annealed KHN and in KHN-FePt.

In situ X-ray Scattering Study of the Formation of Au Nano Crystals During Thermal Annealing

2007 ◽  
Vol 1027 ◽  
Author(s):  
Do Young Noh ◽  
Ki-Hyun Ryu ◽  
Hyon Chol Kang
Keyword(s):  
Thermal Annealing ◽  
Bragg Reflection ◽  
Ex Situ ◽  
X Ray ◽  
Force Microscopy ◽  
X Ray Scattering ◽  
Atomic Force ◽  
Au Thin Films ◽  
Ray Scattering

AbstractThe transformation of Au thin films grown on sapphire (0001) substrates into nano crystals during thermal annealing was investigated by in situ synchrotron x-ray scattering and ex situ atomic force microscopy (AFM). By monitoring the Au(111) Bragg reflection and the low Q reflectivity and comparing them with ex situ AFM images, we found that polygonal-shape holes were nucleated and grow initially. As the holes grow larger and contact each other, their boundary turns into Au nano crystals. The Au nano crystals have a well-defined (111) flat top surface and facets in the in-plane direction.

Synchrotron Small Angle X-Ray Scattering Spectra of Iron-Based Magnetic Fluids

2013 ◽  
Vol 545 ◽  
pp. 31-35 ◽  
Author(s):  
Krit Koyvanich ◽  
Komkrich Chokprasombat ◽  
Chitnarong Sirisathitkul ◽  
Phimphaka Harding ◽  
Supagorn Rugmai
Keyword(s):  
Magnetic Fluid ◽  
Small Angle ◽  
Magnetic Fluids ◽  
Superparamagnetic Nanoparticles ◽  
The Other ◽  
Fept Nanoparticles ◽  
X Ray ◽  
Iron Platinum ◽  
X Ray Scattering ◽  
Ray Scattering

Magnetic fluid is a special class of materials which possesses the advantages of a liquid state of the carrier and a magnetic state of the particles. In addition to the conventional uses in mechanical engineering, magnetic fluids containing magnetite (Fe3O4) superparamagnetic nanoparticles are under research and development for drug delivery, hyperthermia and MRI contrast agents. On the other hand, iron-platinum (FePt) is investigated as materials for ultrahigh density recording. Before their assembly into patterned media, the as-synthesized FePt nanoparticles in superparamagnetic state are commonly stored in forms of magnetic fluids. In this work, iron-platinum (FePt) nanoparticles with their surface modified by oleic acid and oleyleamine were synthesized from the polyol process. The starting material was an environmental friendly iron(III) acetylacetonate and the products were dispersed in n-hexane. In small-angle X-ray scattering (SAXS) measurements at the Synchrotron Light Research Institute, Thailand, each magnetic fluid was injected into a sample cell with aluminum foil windows and the X-ray of wavelength 1.55 Å from BL2.2 was used. The measured SAXS intensity profiles as a function of the scattering vector from 0.27 to 2.30 nm-1 were fitted and compared between two different reactions. Nanoparticles synthesized by using a higher amount of Fe(acac)3 were matched with monodisperse spheres of radius 2.4±0.3 nm. The other reaction with a reducing agent gave rise to smaller nanoparticles of two size distributions. From this work, the potential of synchrotron radiation to complement conventional characterization techniques in the investigation of nanoparticles for high density recording and biomedical applications is underlined.

X-ray scattering study of thermal nanopore templating in hybrid films of organosilicate precursor and reactive four-armed porogen

2006 ◽  
Vol 17 (14) ◽  
pp. 3490-3498 ◽  
Author(s):  
Jinhwan Yoon ◽  
Kyuyoung Heo ◽  
Weontae Oh ◽  
Kyeong Sik Jin ◽  
Sangwoo Jin ◽  
...  
Keyword(s):  
Hybrid Films ◽  
X Ray ◽  
X Ray Scattering ◽  
Scattering Study ◽  
Ray Scattering

Small-Angle X-Ray Scattering Study on Nanostructures of Polyimide Films

2010 ◽  
Vol 27 (9) ◽  
pp. 096103 ◽  
Author(s):  
Liu Xiao-Xu ◽  
Yin Jing-Hua ◽  
Sun Dao-Bin ◽  
Bu Wen-Bin ◽  
Cheng Wei-Dong ◽  
...  
Keyword(s):  
Small Angle ◽  
Polyimide Films ◽  
X Ray ◽  
X Ray Scattering ◽  
Scattering Study ◽  
Ray Scattering

Self-organization of Fe clusters on mesoporous TiO2templates

2014 ◽  
Vol 47 (6) ◽  
pp. 1921-1930 ◽  
Author(s):  
Patrick Ziegler ◽  
Neelima Paul ◽  
Peter Müller-Buschbaum ◽  
Birgit Wiedemann ◽  
Wolfgang Kreuzpaintner ◽  
...  
Keyword(s):  
Magnetic Measurements ◽  
Magnetic Behavior ◽  
Grazing Incidence ◽  
Self Organization ◽  
Hybrid Films ◽  
Correlation Lengths ◽  
X Ray ◽  
Stages Of Growth ◽  
X Ray Scattering ◽  
Out Of Plane

Fe layers with thicknesses between 5 and 100 nm were sputtered on mesoporous nanostructured anatase TiO2templates. The morphology of these hybrid films was probed with grazing-incidence small-angle X-ray scattering and X-ray reflectivity, complemented with magnetic measurements. Three different stages of growth were found, which are characterized by different correlation lengths for each stage. The magnetic behavior correlates with the different growth regimes. At very small thicknesses the TiO2template is coated and a porous Fe film results, with in-plane and out-of-plane magnetization components. With increasing thickness, agglomeration of Fe occurs and the magnetization gradually turns mostly in plane. At large thicknesses, the iron grows independently of the template and the magnetization is predominantly in plane with a bulk-like characteristic.

scholarly journals Engineered chemotaxis core signaling units indicate a constrained kinase-off state

2020 ◽  
Vol 13 (657) ◽  
pp. eabc1328
Author(s):  
Alise R. Muok ◽  
Teck Khiang Chua ◽  
Madhur Srivastava ◽  
Wen Yang ◽  
Zach Maschmann ◽  
...  
Keyword(s):  
Kinase Activity ◽  
Resonance Spectroscopy ◽  
X Ray ◽  
X Ray Scattering ◽  
Cryo Electron Microscopy ◽  
Spin Resonance ◽  
Bacterial Chemoreceptors ◽  
Coupling Protein ◽  
Site Directed Spin Labeling ◽  
Receptor Dimers

Bacterial chemoreceptors, the histidine kinase CheA, and the coupling protein CheW form transmembrane molecular arrays with remarkable sensing properties. The receptors inhibit or stimulate CheA kinase activity depending on the presence of attractants or repellants, respectively. We engineered chemoreceptor cytoplasmic regions to assume a trimer of receptor dimers configuration that formed well-defined complexes with CheA and CheW and promoted a CheA kinase-off state. These mimics of core signaling units were assembled to homogeneity and investigated by site-directed spin-labeling with pulse-dipolar electron-spin resonance spectroscopy (PDS), small-angle x-ray scattering, targeted protein cross-linking, and cryo–electron microscopy. The kinase-off state was especially stable, had relatively low domain mobility, and associated the histidine substrate and docking domains with the kinase core, thus preventing catalytic activity. Together, these data provide an experimentally restrained model for the inhibited state of the core signaling unit and suggest that chemoreceptors indirectly sequester the kinase and substrate domains to limit histidine autophosphorylation.

X-ray scattering study on the electric field-induced interfacial magnetic anisotropy modulation at CoFeB / MgO interfaces

2018 ◽  
Vol 18 (11) ◽  
pp. 1212-1217
Author(s):  
Kyung Mee Song ◽  
Dong-Ok Kim ◽  
Jae-Sung Kim ◽  
Dong Ryeol Lee ◽  
Jun Woo Choi
Keyword(s):  
Electric Field ◽  
Magnetic Anisotropy ◽  
X Ray ◽  
X Ray Scattering ◽  
Scattering Study ◽  
Ray Scattering
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