scholarly journals Importance of the Electrolyte in Obtaining Porous Silicon and How It Modifies the Optical and Structural Proprieties: Optical and Microstructural Investigation

2015 ◽  
Vol 2015 ◽  
pp. 1-6 ◽  
Author(s):  
F. Severiano ◽  
G. García ◽  
L. Castañeda ◽  
M. Salazar Villanueva ◽  
J. Flores Méndez
Keyword(s):  
Porous Silicon ◽  
Raman Scattering ◽  
Hydrofluoric Acid ◽  
Crystalline Silicon ◽  
Energy Dispersive Spectrometer ◽  
Visible Range ◽  
Gravimetric Analysis ◽  
Sem Images ◽  
Microstructural Investigation ◽  
Incremental Change

The effect of using different electrolytes in the physical and optical properties of porous silicon was studied. To do this porous silicon (PS) samples photoluminescent in the visible range from (100) oriented n-type crystalline silicon prepared by anodic etching were obtained. The first electrolyte was composed of a mixture of hydrofluoric acid (HF) and ethanol (CH3-CH2-OH) in a ratio of 1 : 2, respectively. The second was composed of hydrofluoric acid (HF), ethanol (CH3-CH2-OH), and hydrogen peroxide (H2O2) in a ratio of 1 : 1 : 2, respectively. Raman scattering, photoluminescence (PL), gravimetry, scanning electron microscopy (SEM), and energy dispersive spectrometer (EDS) measurements on the PSL were carried out. Raman scattering showed that the disorder in the samples obtained with H2O2is greater than in the samples obtained without this. The PL from PS increased in intensity with the incremental change in the anodization time and showed a blueshift. The blueshift of PL is consistent with the reduction in size of the silicon nanocrystallites. The sizes of nanocrystals were estimated to be 3.08, 2.6, and 2.28 nm. The gravimetric analysis showed that the porosity increased with the incorporation of H2O2. SEM images (morphological analysis) showed an incremental change in the quantity and in the porous size.

Exploring the Length Scale Limits of Porous Silicon Combustion

2015 ◽  
Vol 1758 ◽  
Author(s):  
Nicholas W. Piekiel ◽  
Christopher J. Morris ◽  
Wayne A. Churaman ◽  
David M. Lunking
Keyword(s):  
Porous Silicon ◽  
Crystalline Silicon ◽  
Energetic Material ◽  
Sodium Perchlorate ◽  
Flame Speed ◽  
Small Scale ◽  
Length Scale ◽  
Sem Images ◽  
Thermal Insulator ◽  
On Chip

ABSTRACTThe present study explores the burning of microscale porous silicon channels with sodium perchlorate. These on-chip porous silicon energetics were embedded in crystalline silicon, and therefore surrounded on three sides by an efficient thermal conductor. For slow burning systems, this presents complications as heat loss to the crystalline silicon substrate can result in inconsistent burning or flame extinction. We investigated <100 μm wide porous silicon strips, sparsely filled with sodium perchlorate (NaClO4), to probe the limits of on-chip combustion. Four different etch times were attempted to decrease the dimensions of the porous silicon strips. The smallest size achieved was 12 x 64 µm, and despite the small dimensions, demonstrated the same flame speed as the larger porous silicon strips of 6-7 m/s. We predict that unreacted porous silicon acts as a thermal insulator to aid combustion for slow burning porous silicon channels, and SEM images provide evidence to support this. We also investigated the small scale combustion of a rapidly burning sample (∼1200 m/s). Despite the rapid flame speed, the propagation followed a designed, winding flame path. The use of these small scale porous silicon samples could significantly reduce the energetic material footprint for future microscale applications.

STRUCTURAL AND OPTICAL FEATURES OF POROUS SILICON PREPARED BY ELECTROCHEMICAL ANODIC ETCHING

2009 ◽  
Vol 16 (01) ◽  
pp. 93-97 ◽  
Author(s):  
L. S. CHUAH ◽  
Z. HASSAN ◽  
F. K. YAM ◽  
H. ABU HASSAN
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Porous Silicon ◽  
Raman Scattering ◽  
Raman Spectra ◽  
Raman Peak ◽  
Sem Images ◽  
Anodic Etching ◽  
Etching Duration ◽  
Scanning Electron

Porous silicon (PS) samples were prepared by electrochemical anodic etching of n-type (111) silicon wafers in HF solution. The structural, optical, and chemical features of the PS were investigated in terms of different etching durations. The porous samples were investigated by scanning electron microscopy (SEM), photoluminescence (PL), and Raman scattering. SEM images indicated that the pores increased with the etching duration; however, the etching duration has significant effect on the shape of the pores. PL measurements revealed that the porosity-induced PL intensity enhancement was only observed in the porous samples. Raman spectra showed shifting of PS Raman peak to lower frequency relative to non-porous silicon Raman peak.

Enhanced electrical and luminescent performance of a porous silicon/MEH-PPV nanohybrid synthesized by anodization and repeated spin coating

RSC Advances ◽  
2015 ◽  
Vol 5 (121) ◽  
pp. 99892-99898 ◽  
Author(s):  
A. M. S. Salem ◽  
F. A. Harraz ◽  
S. M. El-Sheikh ◽  
H. S. Hafez ◽  
I. A. Ibrahim ◽  
...  
Keyword(s):  
Porous Silicon ◽  
Spin Coating ◽  
Hydrofluoric Acid ◽  
Crystalline Silicon ◽  
Electrochemical Anodization ◽  
Single Crystalline Silicon ◽  
Single Crystalline ◽  
Pore Sizes ◽  
Wide Range

The electrochemical anodization of a single crystalline silicon in hydrofluoric acid-based solution leads to the formation of porous silicon (PSi) with tunable pore sizes and morphology for a wide range of technological applications.

Raman Scattering in Electrochemically Prepared Porous Silicon

1991 ◽  
Vol 256 ◽  
Author(s):  
Y. -J. Wu ◽  
X. -S. Zhao ◽  
P. D. Persans
Keyword(s):  
Porous Silicon ◽  
Raman Scattering ◽  
Amorphous Silicon ◽  
Room Temperature ◽  
High Efficiency ◽  
Silicon Oxide ◽  
Electrochemical Etching ◽  
Visible Range ◽  
Microcrystalline Silicon ◽  
Hydrogenated Amorphous

ABSTRACTPorous silicon of various porosity has been prepared by electrochemical etching of silicon with different doping levels. Room temperature photoluminescence in the visible range is observed from the powder scraped from the top layer of the etched samples. In this paper we use Raman scattering to characterize the source of the high efficiency photoluminescence. We have also studied microcrystalline silicon prepared by thermal annealing of hydrogenated amorphous silicon/amorphous silicon oxide multilayers.

Anisotropic and polarization effects in Raman scattering in porous silicon

1995 ◽  
Vol 255 (1-2) ◽  
pp. 139-142 ◽  
Author(s):  
I. Gregora ◽  
B. Champagnon ◽  
L. Saviot ◽  
Y. Monin
Keyword(s):  
Porous Silicon ◽  
Raman Scattering ◽  
Polarization Effects

Investigation of porous silicon by Raman scattering and second-harmonic generation techniques

1994 ◽  
Author(s):  
Leonid A. Golovan ◽  
Andrei V. Zoteyev ◽  
Pavel K. Kashkarov ◽  
Viktor Y. Timoshenko
Keyword(s):  
Porous Silicon ◽  
Raman Scattering ◽  
Second Harmonic Generation ◽  
Harmonic Generation ◽  
Second Harmonic

The Photoluminescence Enhancement and Stability of Porous Silicon by Cathodic Reduction and Acid Treatment

2014 ◽  
Vol 887-888 ◽  
pp. 458-461
Author(s):  
Chang Qing Li ◽  
Kun Wang ◽  
Pei Jia Liu ◽  
Qi Ming
Keyword(s):  
Electron Microscope ◽  
Porous Silicon ◽  
Acid Treatment ◽  
Cathodic Reduction ◽  
Luminescence Properties ◽  
Sem Images ◽  
Photoluminescence Enhancement ◽  
The Stability ◽  
Scanning Electron ◽  
Cathode Reduction

Porous silicon (PSi) was fabricated by using electrochemical anodic etching method. Then acid treatment and cathode reduction treatment were employed to improve the luminescence properties and stability of PSi material. Photoluminescence (PL) measurements and scanning electron microscope (SEM) were used to observe the luminescence properties and microstructure of samples, respectively. The results of PL measurements showed that the PL intensity and the stability of luminescence of samples after cathodic reduction and acid treatment were significantly improved. The SEM images showed that the porosity of PSi may be increased through the cathodic reduction treated.

Li(Ni1/3Co1/3Mn1/3)O2 with High Rate Capability Synthesized via a Novel Gel-Combustion Method

2011 ◽  
Vol 391-392 ◽  
pp. 973-977
Author(s):  
Jing Mao ◽  
Ke Hua Dai ◽  
Yu Chun Zhai
Keyword(s):  
Energy Dispersive Spectrometer ◽  
Rate Capability ◽  
Chelating Agent ◽  
Combustion Method ◽  
Xrd Analysis ◽  
High Rate ◽  
High Rate Capability ◽  
Sem Images ◽  
Gel Combustion ◽  
Gel Combustion Method

Li(Ni1/3Co1/3Mn1/3)O2material with high rate capability was synthesized by a novel gel-combustion method using polyvinylpyrrolidone as a polymer chelating agent and a fuel. X-ray diffraction (XRD), scanning electron microscope (SEM) and energy dispersive spectrometer (EDS) were used to study the structure, morphology and element distribution of the Li(Ni1/3Co1/3Mn1/3)O2material. XRD analysis showed that all samples were α-NaFeO2structure and Li(Ni1/3Co1/3Mn1/3)O2prepared at 900 °C had the highest c/a of 4.977 indicating the highest layered-ness. EDS scan demonstrated that the precursor was homogeneous. SEM images indicated all samples were well crystallized. Charge and discharge tests showed all samples had good rate capability. Among them, Li(Ni1/3Co1/3Mn1/3)O2prepared at 900 °C had the highest capacity and the best rate capability. It delivered 162.1 mAh•g−1at 0.25 C between 2.5 and 4.3 V and the capacity retention was about 81% compared to that of 0.25C rate.

scholarly journals Possible source of ancient carbon in phytolith concentrates from harvested grasses

2012 ◽  
Vol 9 (5) ◽  
pp. 1873-1884 ◽  
Author(s):  
G. M. Santos ◽  
A. Alexandre ◽  
J. R. Southon ◽  
K. K. Treseder ◽  
R. Corbineau ◽  
...  
Keyword(s):  
Plant Tissue ◽  
Atmospheric Carbon Dioxide ◽  
Energy Dispersive Spectrometer ◽  
Nutrient Acquisition ◽  
Published Data ◽  
Plant Nutrient ◽  
Before Present ◽  
Sem Images ◽  
Carbon Dioxide Co2 ◽  
Scanning Electron

Abstract. Plants absorb and transport silicon (Si) from soil, and precipitation of Si within the living plants results in micrometric amorphous biosilica particles known as phytoliths. During phytolith formation, a small amount of carbon (<2%) can become occluded in the silica structure (phytC) and therefore protected from degradation by the environment after plant tissue decomposition. Since the major C source within plants is from atmospheric carbon dioxide (CO2) via photosynthesis, the current understanding is that the radiocarbon (14C) content of phytC should reflect the 14C content of atmospheric CO2 at the time the plant is growing. This assumption was recently challenged by 14C data from phytoliths extracted from living grasses that yielded ages of several thousand years (2–8 kyr BP; in radiocarbon years "Before Present" (BP), "Present" being defined as 1950). Because plants can take up small amounts of C of varying ages from soils (e.g., during nutrient acquisition), we hypothesized that this transported C within the plant tissue could be attached to or even embedded in phytoliths. In this work, we explore this hypothesis by reviewing previously published data on biosilica mineralization and plant nutrient acquisition as well as by evaluating the efficiency of phytolith extraction protocols from scanning electron microscope (SEM) images and energy dispersive spectrometer (EDS) analyses from harvested grasses phytolith concentrates. We show that current extraction protocols are inefficient since they do not entirely remove recalcitrant forms of C from plant tissue. Consequently, material previously measured as "phytC" may contain at least some fraction of soil-derived C (likely radiocarbon-old) taken up by roots. We also suggest a novel interpretation for at least some of the phytC – which enters via the root pathway during nutrient acquisition – that may help to explain the old ages previously obtained from phytolith concentrates.

Tribological and thermomechanical analysis of CaO (quicklime) particulates filled ZA-27 alloy composites for bearing application

2015 ◽  
Vol 232 (1) ◽  
pp. 20-34 ◽  
Author(s):  
Swati Gangwar ◽  
Amar Patnaik ◽  
IK Bhat
Keyword(s):  
Wear Rate ◽  
Normal Load ◽  
Energy Dispersive Spectrometer ◽  
Thermo Gravimetric Analysis ◽  
Research Work ◽  
Surface Profile ◽  
Specific Wear Rate ◽  
Gravimetric Analysis ◽  
Load Range ◽  
Environment Temperature

This research work investigates friction and wears behaviour of CaO filler / particulate reinforced ZA-27 alloy composites. Pin-on-disk tribometer confining to ASTM G 99 standard with EN-31 hardened steel disc was used to simulate the tribological performance experimentally. The tribological parameters were evaluated over a normal load range of 5–45 N, sliding velocity of 1.047–5.235 m/s., sliding distance of 500–2500 m, environment temperature of 25–45℃ and filler content range of 0–10 wt%. The various alloy composites were fabricated under vacuum environment by high-temperature gravity casting technique. The steady-state specific wear rate and coefficient of friction were evaluated under different boundary conditions and thereafter Taguchi design of experiment methodology was adopted to compute the experimental specific wear rate of the proposed alloy composites. The dynamic mechanical analysis and thermo-gravimetric analysis study were also performed in order to observe the thermal characteristics of the composites at higher temperature. Finally, the surface morphology of the worn samples was performed using field-emission scanning electron microscope to understand the wear mechanism prevailed at rubbing surfaces and then atomic force microscopy analysis was studied to evaluate the surface profile of the worn sample. At the end, energy-dispersive spectrometer analysis was also performed to find out the elemental compositions of the worn alloy composites.

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