Composition and Structure of Spark Eroded Porous Silicon

ABSTRACTPorous silicon which has been prepared by a “dry” technique, that is, by spark erosion, yields similar photoluminescence spectra as anodically etched porous silicon which has been prepared in aqueous solutions. Fourier transform infrared spectra reveal that the dominant features in spark eroded silicon are the Si-O-Si stretching mode and the Si-O-Si bending mode. No infrared vibrational modes characteristic for siloxene have been found in spark eroded Si. Results from X-ray and electron diffraction studies suggest that spark eroded Si involves minute polycrystalline silicon particles which are imbedded in an amorphous matrix.

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USXES AND OPTICAL PHENOMENA IN Si LOW-DIMENSIONAL STRUCTURES DEPENDENT ON MORPHOLOGY AND SILICON OXIDE COMPOSITION ON Si SURFACE

Surface Review and Letters ◽

10.1142/s0218625x02003329 ◽

2002 ◽

Vol 09 (02) ◽

pp. 1047-1052 ◽

Cited By ~ 10

Author(s):

T. V. TORCHYNSKA ◽

M. MORALES RODRIGUEZ ◽

G. P. POLUPAN ◽

L. I. KHOMENKOVA ◽

N. E. KORSUNSKAYA ◽

...

Keyword(s):

Porous Silicon ◽

Emission Spectroscopy ◽

Silicon Oxide ◽

Radiative Transition ◽

Photoluminescence Spectra ◽

Photoluminescence Band ◽

X Ray ◽

Force Microscopy ◽

Atomic Force ◽

Low Dimensional

It has been shown that the intensive and broad "red" photoluminescence band in porous silicon is a nonelementary one and could be decomposed on at least three elementary bands. Photoluminescence, ultrasoft X-ray emission spectroscopy, infrared absorption and atomic force microscopy methods were used to study the reasons for both luminescence band appearance in porous silicon photoluminescence spectra, prepared in different technological conditions. The mechanisms of radiative transition for both elementary bands have been discussed as well.

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Structural and Enhanced Optical Properties of Stabilized γ‒Bi2O3 Nanoparticles: Effect of Oxygen Ion Vacancies

Nanomaterials ◽

10.3390/nano10061023 ◽

2020 ◽

Vol 10 (6) ◽

pp. 1023 ◽

Cited By ~ 2

Author(s):

Ashish Chhaganlal Gandhi ◽

Chia-Liang Cheng ◽

Sheng Yun Wu

Keyword(s):

Room Temperature ◽

Excess Oxygen ◽

Ambient Atmosphere ◽

Photoluminescence Spectra ◽

X Ray Diffraction ◽

X Ray ◽

Band Emission ◽

Oxygen Ion ◽

Integrated Intensity ◽

Effect Of Oxygen

We report the synthesis of room temperature (RT) stabilized γ–Bi2O3 nanoparticles (NPs) at the expense of metallic Bi NPs through annealing in an ambient atmosphere. RT stability of the metastable γ–Bi2O3 NPs is confirmed using synchrotron radiation powder X-ray diffraction and Raman spectroscopy. γ–Bi2O3 NPs exhibited a strong red-band emission peaking at ~701 nm, covering 81% integrated intensity of photoluminescence spectra. Our findings suggest that the RT stabilization and enhanced red-band emission of γ‒Bi2O3 is mediated by excess oxygen ion vacancies generated at the octahedral O(2) sites during the annealing process.

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Preparation of Porous Hydroxyapatite Using Cetyl Trimethyl Ammonium Bromide as Surfactant for the Removal of Lead Ions from Aquatic Solutions

Polymers ◽

10.3390/polym13101617 ◽

2021 ◽

Vol 13 (10) ◽

pp. 1617

Author(s):

Silviu-Adrian Predoi ◽

Carmen Steluta Ciobanu ◽

Mikael Motelica-Heino ◽

Mariana Carmen Chifiriuc ◽

Monica Luminita Badea ◽

...

Keyword(s):

Cetyl Trimethyl Ammonium Bromide ◽

Morphological Changes ◽

Low Cost ◽

Lead Ions ◽

Ammonium Bromide ◽

Porous Hydroxyapatite ◽

X Ray ◽

Composition And Structure ◽

Cetyl Trimethyl Ammonium ◽

Co Precipitation

In the present study, a new low-cost bioceramic nanocomposite based on porous hydroxyapatite (HAp) and cetyl trimethyl ammonium bromide (CTAB) as surfactant was successfully obtained by a simple chemical co-precipitation. The composition and structure of the HAp-CTAB were characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, transmission electron microscopy (TEM), scanning electron microscope (SEM) equipped with an energy dispersive X-ray (EDX) spectrometer, and N2 adsorption/desorption analysis. The capacity of HAp-CTAB nanocomposites to remove the lead ions from aqueous solutions was studied by adsorption batch experiments and proved by Langmuir and Freundlich models. The Pb2+ removal efficiency of HAp-CTAB biocomposite was also confirmed by non-destructive ultrasound studies. The cytotoxicity assays showed that the HAp-CTAB nanocomposites did not induce any significant morphological changes of HeLa cells after 24 h of incubation or other toxic effects. Taken together, our results suggests that the obtained porous HAp-CTAB powder could be used for the decontamination of water polluted with heavy metals, such as Pb2+.

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Rapid Thermal Oxidation for Passivation of Porous Silicon

MRS Proceedings ◽

10.1557/proc-342-91 ◽

1994 ◽

Vol 342 ◽

Cited By ~ 6

Author(s):

I. BÁrsony ◽

J.G.E. Klappe ◽

É. Vázsonyi ◽

T. Lohner ◽

M. Fried

Keyword(s):

Porous Silicon ◽

Mechanical Stability ◽

Porous Substrate ◽

X Ray Diffraction ◽

X Ray ◽

Si Substrates ◽

Tetragonal Lattice ◽

Optical Heating ◽

Vertical Inhomogeneity ◽

Highly Porous

ABSTRACTChemical and mechanical stability of porous silicon layers (PSL) is the prerequisite of any active (luminescent) or passive (e.g. porous substrate) integrated applications. In this work X-ray diffraction (XRD) was used to analyze quantitatively the strain distribution obtained in different morphology PSL that were prepared on (100) p and p+Si substrates. Tetragonal lattice constant distortion can be as high as 1.4% in highly porous “as-prepared” samples. Incoherent optical heating RTO is governed by the absorption in the oxidized specimen. PSL show vertical inhomogeneity according to interpretation of spectroscopic ellipsometry (SE) data. Oxygen incorporation during RTO is controlled by specific surface (in p+ proportional, in p inversely proportional with porosity), while the developing compressive stress depends on pore size, and decreases with porosity in both morphologies.

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Luminescent Properties of Zn2SiO4:Eu3+,Dy3+ Phosphors via Sol-Gel Process

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.217-219.733 ◽

2012 ◽

Vol 217-219 ◽

pp. 733-736

Author(s):

Xiu Mei Han ◽

Shu Ai Hao ◽

Ying Ling Wang ◽

Gui Fang Sun ◽

Xi Wei Qi

Keyword(s):

Thermal Analysis ◽

Ir Spectra ◽

Sol Gel ◽

Luminescent Properties ◽

Photoluminescence Spectra ◽

X Ray Diffraction ◽

X Ray ◽

Sol Gel Process ◽

Ft Ir

Zn2SiO4:Eu3+, Dy3+ phosphors have been prepared through the sol-gel process. X-ray diffraction (XRD), thermogravimetric and ddifferential thermal analysis (TG-DTA), FT-IR spectra and photoluminescence spectra were used to characterize the resulting phosphors. The results of XRD indicated that the phosphors crystallized completely at 1000oC. In Zn2SiO4:Eu3+,Dy3+ phosphors, the Eu3+ and Dy3+ show their characteristic red(613nm, 5D0-7F2), blue (481nm, 4F9/2–6H15/2) and yellow (577nm, 4F9/2–6H13/2) emissions.

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Controlling water evaporation through self-assembly

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1604134113 ◽

2016 ◽

Vol 113 (37) ◽

pp. 10275-10280 ◽

Cited By ~ 18

Author(s):

Kevin Roger ◽

Marianne Liebi ◽

Jimmy Heimdal ◽

Quoc Dat Pham ◽

Emma Sparr

Keyword(s):

Self Assembly ◽

Feedback Loop ◽

Ambient Air ◽

Underlying Mechanism ◽

Water Evaporation ◽

Air Humidity ◽

X Ray ◽

X Ray Scattering ◽

Composition And Structure ◽

Living Organisms

Water evaporation concerns all land-living organisms, as ambient air is dryer than their corresponding equilibrium humidity. Contrarily to plants, mammals are covered with a skin that not only hinders evaporation but also maintains its rate at a nearly constant value, independently of air humidity. Here, we show that simple amphiphiles/water systems reproduce this behavior, which suggests a common underlying mechanism originating from responding self-assembly structures. The composition and structure gradients arising from the evaporation process were characterized using optical microscopy, infrared microscopy, and small-angle X-ray scattering. We observed a thin and dry outer phase that responds to changes in air humidity by increasing its thickness as the air becomes dryer, which decreases its permeability to water, thus counterbalancing the increase in the evaporation driving force. This thin and dry outer phase therefore shields the systems from humidity variations. Such a feedback loop achieves a homeostatic regulation of water evaporation.

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ROOM TEMPERATURE PHOTOLUMINESCENCE OF POLYCRYSTALLINE SIC PREPARED FROM CARBON-SATURATED SI MELT

International Journal of Modern Physics B ◽

10.1142/s021797920201083x ◽

2002 ◽

Vol 16 (06n07) ◽

pp. 1047-1051

Author(s):

JIANPING MA ◽

ZHIMING CHEN ◽

GANG LU ◽

MINGBIN YU ◽

LIANMAO HANG ◽

...

Keyword(s):

Electron Microscopy ◽

Photoelectron Spectroscopy ◽

Room Temperature ◽

Uv Light ◽

X Ray Diffraction ◽

X Ray ◽

Room Temperature Photoluminescence ◽

Composition And Structure ◽

Light Excitation ◽

Scanning Electron

Intense photoluminescence (PL) has been observed at room temperature from the polycrystalline SiC samples prepared from carbon-saturated Si melt at a temperature ranging from 1500 to 1650°C. Composition and structure of the samples have been confirmed by means of X-ray photoelectron spectroscopy, X-ray diffraction and scanning electron microscopy. PL measurements with 325 nm UV light excitation revealed that the room temperature PL spectrum of the samples consists of 3 luminescent bands, the peak energies of which are 2.38 eV, 2.77 eV and 3.06 eV, respectively. The 2.38 eV band is much stronger than the others. It is suggested that some extrinsic PL mechanisms associated with defect or interface states would be responsible to the intensive PL observed at room temperature.

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Evidence of x-ray absorption-edge shift as a function of luminescence wavelength in porous silicon

Physical Review B ◽

10.1103/physrevb.62.9911 ◽

2000 ◽

Vol 62 (15) ◽

pp. 9911-9914 ◽

Cited By ~ 17

Author(s):

G. Dalba ◽

N. Daldosso ◽

P. Fornasini ◽

M. Grimaldi ◽

R. Grisenti ◽

...

Keyword(s):

Porous Silicon ◽

Absorption Edge ◽

X Ray ◽

Absorption Edge Shift ◽

X Ray Absorption

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Sb-Te Phase-change Nanowires by Templated Electrodeposition

MRS Proceedings ◽

10.1557/opl.2012.1105 ◽

2012 ◽

Vol 1431 ◽

Cited By ~ 2

Author(s):

C. A. Ihalawela ◽

R. E. Cook ◽

X. M. Lin ◽

H. H. Wang ◽

G. Chen

Keyword(s):

Phase Change ◽

Dominant Role ◽

Pulse Excitation ◽

Aao Template ◽

X Ray ◽

High Data ◽

Aspect Ratios ◽

Composition And Structure ◽

Future Challenges ◽

Non Volatile Memory

ABSTRACTPhase-change memory materials (PCMMs) are semiconductors that exhibit rapid order-disorder transition under electrical or optical pulse excitation. Currently thin-film-based PCMMs play a dominant role in fabrication of non-volatile memory devices. In contrast, phase-change nanowires (PCNWs) have the potential to overcome future challenges such as high data density and low power consumption. Among the various methods to synthesize PCNWs, the vapor-liquid-solid method has been reported previously. In this paper, we report synthesis of Sb-Te PCNWs using a templated electrochemical method. Nanoporous anodic aluminum oxide (AAO) was used as a template for the growth of nanowires. Sb-Te PCNWs with different compositions, diameters and aspect ratios were grown inside the AAO template by electrodeposition. Composition and structure of these nanowires were characterized by energy dispersive X-ray spectroscopy, X-ray diffraction, and scanning and transmission electron microscopy. It is found that electrodeposition through nanosized channels results in materials that are quite different from those electrodeposited on unrestricted surface. The mechanism of nanowire formation inside the channels of AAO template is discussed.

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