10,966 research outputs found
Improved tunneling magnetoresistance in (Ga,Mn)As/AlO(x)/CoFeB magnetic tunnel junctions
No full textWe fabricated (Ga,Mn)As/AlO(x)/Co(40)Fe(40)B(20) magnetic tunnel junctions with ferromagnetic semiconductor/insulator/ferromagnetic metal (S/I/F) structure. The treatments of pre-annealing and post-plasma cleaning on the (Ga,Mn) As film were introduced before the growth of the subsequent layers. A high tunneling magnetoresistance (TMR) ratio of 101% is achieved at 2 K, and the spin polarization of (Ga,Mn) As, P = 56.8%, is deduced from Julliere's formula. The improved TMR ratio is primarily due to the improved magnetism of (Ga,Mn) As layer by low-temperature annealing and cleaned interface between (Ga,Mn) As and AlO(x) attained by subsequent plasma cleaning process. (C) 2011 American Institute of Physics. [doi:10.1063/1.3603946
Effects of Mn on the crystal structure of alpha-Al(Mn,Fe)Si particles in A356 alloys
No full textIn a commercial Al-7.0Si-0.38Mg cast alloy (A356) with 0.20wt% Fe, added Mn modifies acicular beta-Al5FeSi particles to less acicular alpha-Al(Mn,Fe)Si in both crystallization and precipitation conditions. The crystal structure of alpha-Al(Mn,Fe)Si changes from body-centered cubic (bcc)/ simple cubic (sc) to Pm3 structures in response to an increase in the bulk Mn content of the alloy. The alpha-Al(Mn,Fe)Si particles (50-200nm) precipitate during solution treatment and their precipitation temperature is about 485 degrees C in the as-cast condition. (c) 2006 Elsevier B.V. All rights reserved.This work was supported by the Korea materials and components industry agency (inter-research consortium for MCT)
Mn-Doped Nano-Hydroxyapatites as Theranostic Agents with Tumor pH-Amplified MRI-Signal Capabilities for Guiding Photothermal Therapy
No full textChengyu Li, Ziyou Ding, Yingchao Han State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Biomedical Materials and Engineering Research Center of Hubei Province, Wuhan University of Technology, Wuhan, 430070, People’s Republic of ChinaCorrespondence: Yingchao Han, Email [email protected]: The integration of diagnostic and therapeutic functions into a biosafe nanoplatform with intelligent response functions at the tumor microenvironment (TME) is a promising strategy for cancer therapy.Methods: Mn-doped nano-hydroxyapatite (nHAPMn) nanoparticles were successfully prepared via a simple coprecipitation method for magnetic resonance imaging (MRI)-guided photothermal therapy. This study is the first to report on the use of Mn to render biodegradable hydroxyapatite suitable for MRI and effective photothermal therapy (PTT) simultaneously by regulating the pH of nHAPMn during the preparation process.Results: Combined with near-infrared (NIR) laser irradiation, a photothermal conversion efficiency of 26% and effective photothermal lethality in vitro were achieved. Moreover, the degradation of nHAPMn led to the release of Mn ions and amplified the MRI signals in an acidic TME, which confirmed that nHAPMn had a good pH-responsive MRI capacity in solid tumors. In animal experiments, tumors in the nHAPMn5+NIR group completely abated after 14 days of treatment, with no significant recurrence during the experiment.Conclusion: Therefore, nHAPMn is promising as a nanotheranostic agent and can be effective in clinical diagnosis and therapy for treating cancer.Graphical Abstract: Keywords: photothermal therapy, magnetic resonance imaging, hydroxyapatite, manganese, pH-amplifie
Mechanistic study for enhanced CO oxidation activity on (Mn,Fe) co-doped CeO2(111)
No full textOwing to the unique properties such as facile redoxability and high stability, ceria has been used for a wide range of applications including automotive emission control, catalytic combustion, hydrocarbon reforming, and electrocatalytic reactions. It is well known that enhanced chemical reactivity can be achieved on transition metal (TM)-doped ceria nano-catalysts. In particular, co-doping of TM on CeO2 surface has recently opened a great potential to improve the catalytic activity compared to the single doped one. In this study, we performed OFT calculations to compare the activity of CO oxidation between Mn-, Fe-, and (Mn,Fe)-doped CeO2(111) via Mars-van Krevelen (MvK) mechanism. We firstly verified that a conventional linear relationship between oxygen vacancy formation energy and the catalytic activity of CO oxidation is also effective for the co-doped CeO2(111). It turns out that the energy required to create oxygen vacancy (E-vf), that is a key descriptor of the reactivity, will be extremely useful to rapidly screen the catalytic activity on co-doped oxide system. Then, we investigated the entire reaction profile of CO oxidation via the MvK mechanism on Fe-, Mn-and (Mn,Fe)-doped CeO2(111). Based on the results, we confirmed the improved activity of CO oxidation on the co-doped system, which was in good agreement with the prediction from E-vf. From this study, we believe that the co-doping of TM on oxide catalysts will be a noble strategy to enhance the catalytic activity. (C) 2016 Elsevier B.V. All rights reserved.11Nsciescopu
Nonlinear influence of excess Mn on the magnetoelastic transition in (Mn,Cr)<sub>2</sub>Sb
No full textThe influence of excess Mn on the magnetoelastic ferromagnetic-to-antiferromagnetic transition Tt in the magnetocaloric compound (Mn,Cr)2Sb has been studied. With increasing excess Mn the magnetoelastic transition temperature for (Mn,Cr)2Sb initially increases and then decreases. This trend is accompanied by a strong reduction of the (Mn,Cr)Sb secondary phase. With increasing excess Mn a higher Cr content was found in the (Mn,Cr)Sb secondary phase in comparison to the matrix phase. This competition for Cr leads to a nonlinear dependence of Tt with increasing excess Mn at a fixed nominal Cr content. However, we observed that Tt depends linear on the c/a ratio for a wide range of temperatures from 170 to 350 K. A compositional diagram of the c/a ratio was constructed to assist the selection of (Mn,Cr)2Sb alloys with a desired transition temperature.RST/Fundamental Aspects of Materials and Energ
Mn-doped Sequentially Electrodeposited Co-based Oxygen Evolution Catalyst for Efficient Anion Exchange Membrane Water Electrolysis
No full textDesigning high-performance and durable oxygen evolution
reaction
(OER) catalysts is important for green hydrogen production through
anion exchange membrane water electrolysis (AEMWE). Herein, a series
of Mn-doped Co-based OER catalysts supported on FeOxHy (FCMx) are presented to enhance the OER activity. Mn doping effectively
reduces the size of the Co oxide particles, thereby augmenting the
active surface area. Moreover, Mn doping induces the creation of oxygen
vacancies, leading to an efficient structural conversion during the
OER, which is confirmed via in situ Raman spectroscopy. Under optimal
conditions, the catalyst exhibits an overpotential of 234.4 mV at
10 mA cm–2 and a Tafel slope of 37.2 mV dec–1 under half-cell conditions. The AEMWE single-cell
system demonstrates a current density of 1560 mA cm–2 at 1.8 V at 60 °C with a degradation rate of 0.4 mV h–1 for 500 h at 500 mA cm–2. Our development of a
robust OER catalyst represents notable progress in the field of nonprecious-metal
water electrolysis, marking a step toward cost-effective green hydrogen
production
Tunneling magnetoresistance in CoFeB/GaAs/(Ga,Mn)As hybrid magnetic tunnel junctions
No full textWe reported the all electronic demonstration of spin injection and detection in the trilayers with hybrid structure of CoFeB/GaAs/(Ga,Mn)As (metal/insulator semiconductor) by probing the magnetoresistance at low temperature from 1.8 to 30 K. Tunneling magnetoresistance (TMR) ratios of 3.8%, 4.7%, 2.9%, and 1.4% at 1.8, 10, 20, and 30 K, respectively, were observed. Bias dependence of both the junction resistance and TMR ratio was studied systematically. V-half at which TMR drops to half of its maximum is 6.3 mV, being much smaller compared to that observed in (Ga,Mn)As/ZnSe/Fe and (Ga,Mn)As/AlAs/MnAs hybrid structures, indicating lower Fermi energy of (Ga,Mn)As
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