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3 Acta Physica Polonica A

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Corrosion Behavior of Crofer 22APU for Metallic Interconnects in Single and Dual Atmosphere Exposures at 1073 K

100%

Stygar M. , Matsuda K. , Lee S. , Brylewski T.

Acta Physica Polonica A

2017

tom 131

nr 5

1394-1398

To determine the impact of an oxidizing Ar-H₂-H₂O/air dual atmosphere on the kinetics and mechanism of oxidation of the Crofer 22APU steel as compared to oxidation in a single atmosphere (Ar-H₂-H₂O or air), the oxidation kinetics of this steel were investigated both in single and dual reaction atmospheres at 1073 K during 100, 250, 500, and 1000 h of oxidation. Detailed morphological observations and the results of chemical composition analyses carried out using transmission electron microscopy combined with energy-dispersive X-ray spectroscopy revealed the presence of Fe in the scale formed on the cathode side in the dual atmosphere. Based on morphological observations (scanning- and transmission electron microscopies) and chemical and phase composition analyses (energy-dispersive X-ray spectroscopy and X-ray diffraction, respectively) of the products of oxidation of the Crofer 22APU steel, and on the determined oxidation kinetics, a mechanism describing scale growth on both sides of the steel during its oxidation in conditions involving a gradient of the chemical potential of oxygen and hydrogen was proposed.

Gamma-C₂S Synthesis from Fly Ash of Fluidize-Bed Boiler for CO₂ Capture

100%

Na S. , Kang S. , Lee S. , Song M.

Acta Physica Polonica A

2015

tom 127

nr 4

1282-1285

This paper describes the CO₂ capture performance of cement blended paste incorporating gamma-dicalcium silicate (gamma-C₂S) made with industrial by-products, by taking into consideration of effect of CaCO₃, fly ash replacement ratio under the sintering process. X-ray diffraction method was conducted in order to quantitatively investigate the gamma-C₂S content. CO₂ capture performance of mortar sample incorporating gamma-C₂S was investigated by means of compressive strength test using accelerated carbonation chamber. The experimental results revealed that the kind of CaCO₃ would affect the affect the formation of gamma-C₂S after the sintering with respect to the XRD-Rietveld analysis. Moreover, it is confirmed that compressive strength of mortar sample incorporating gamma-C₂S has the same tendency at curing age of 3, 7 and 28days. Blended mortar sample made with 10 wt.% replacement ratio of gamma-C₂S had high compressive strength value compared to normal mortar sample, therefore, incorporating gamma-C₂S had a positive effect on the compressive strength after accelerated carbonation. Finally, the waste foundry sand powder may be alternative to produce gamma-C₂S.

Influence of Growth Break before Capping on Photoluminescence Dynamics of CdSe/ZnSe Self-Assembled Quantum Dots

75%

Nowak S. , Suffczyński J. , Goryca M. , Kossacki P. , Gaj J. , Lee S. , Furdyna J.

Acta Physica Polonica A

2008

tom 114

nr 5

1267-1271

Influence of growth breaks before capping of CdSe self-assembled quantum dot layers on photoluminescence dynamics was examined in three samples. Short (5s) break resulted only in a small blue shift, caused probably by partial strain relaxation and/or Zn interdiffusion. Long (20 min) break induced a strong broadening and red shift of the spectra, combined with a dramatic slow down of the photoluminescence decays. The main result of the long break was identified as introduction of defects (impurities), which generate local electric fields and act as traps of photogenerated carriers.

Exchange Coupling in Magnetic Semiconductor Multilayers and Superlattices

75%

Furdyna J. , Leiner J. , Liu X. , Dobrowolska M. , Lee S. , Chung J. , Kirby B.

The study of ferromagnetic semiconductors continues to be of great interest because of their potential for spintronic devices. While there has been much progress in our understanding of ferromagnetic semiconductor materials - particularly of the canonical III-V system Ga_{1-x}Mn_xAs - many issues still remain unresolved. One of these is the nature of interlayer exchange coupling in GaMnAs-based multilayers, an issue that is important from the point of view of possible spintronic applications. In this connection, it is important to establish under what conditions the interlayer exchange coupling between successive GaMnAs layers is antiferromagnetic or ferromagnetic, since manipulation of such interlayer exchange coupling can then be directly applied to achieve giant magnetoresistance and other devices based on this material. In this review we will describe magneto-transport, magnetization, and neutron reflectometry experiments applied to two types of GaMnAs-based multilayer structures - superlattices and tri-layers - consisting of GaMnAs layers separated by non-magnetic GaAs spacers. These measurements serve to identify conditions under which AFM coupling will occur in such GaMnAs/GaAs multilayer systems, thus providing us the information which can be used for manipulating magnetization (and thus also giant magnetoresistance) in structures based on the ferromagnetic semiconductor GaMnAs.