Study of growth of dot and column in porous silicon samples of various thicknesses prepared at a constant current density

2015 ◽  
Vol 73 ◽  
pp. 110-115 ◽  
Author(s):  
Fateh Singh Gill ◽  
Varij Panwar ◽  
Himanshu Gupta ◽  
G.S. Kalra ◽  
Shanta Chawla ◽  
...  
Keyword(s):  
Porous Silicon ◽  
Current Density ◽  
Constant Current ◽  
Constant Current Density

Anodization Current Density Independent Photoluminescence of Porous Silicon

2013 ◽  
Vol 538 ◽  
pp. 85-88
Author(s):  
Yuan Ming Huang ◽  
Bao Gai Zhai ◽  
Qing Lan Ma
Keyword(s):  
Porous Silicon ◽  
Current Density ◽  
Hydrofluoric Acid ◽  
Photoluminescence Spectrum ◽  
Electronic Devices ◽  
Constant Current ◽  
Peak Wavelength ◽  
General Belief ◽  
Constant Current Density

Porous silicon (PS) is usually prepared by means of the anodization under constant current density, and fabrication of PS is a key step towards the realization of all-silicon electronic devices. It is a general belief that the photoluminescent properties of electrochemically etched PS depend on the anodization current density. In this work, we electrochemically prepared a series of PS films in the electrolyte of hydrofluoric acid by varying anodizing current density in the range of 1-70 mA/cm2. In spite of the different anodizing current density, the peak wavelength of the photoluminescence spectrum of the electrochemically anodized PS does not depend on the anodization current density. SEM has been utilized to characterize the morphology of the prepared PS films, and the mechanism is discussed for the anodization current independent photoluminescence of PS.

Study on Special Morphology Hydroxyapatite Bioactive Coating by Electrochemical Deposition

2013 ◽  
Vol 537 ◽  
pp. 256-260
Author(s):  
Cai Ge Gu ◽  
Qian Gang Fu ◽  
He Jun Li ◽  
Jin Hua Lu ◽  
Lei Lei Zhang
Keyword(s):  
Electrochemical Deposition ◽  
Current Density ◽  
Electrolyte Concentration ◽  
Spherical Particles ◽  
Constant Current ◽  
Constant Current Density ◽  
Depth Direction ◽  
Special Morphology ◽  
Calcium Phosphate Coatings ◽  
Coating Weight

Bioactive calcium phosphate coatings were deposited on carbon/carbon（C/C） composites using electrochemical deposition technique. The effects of electrolyte concentration and constant current density on morphology, structure and composition of the coating were systematically investigated using scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier transformed infrared (FTIR) spectroscopy. The results show that, the coating weight elevated gradually with the increase of electrolyte concentration, and the morphology of coatings changed from spherical particles to nanolamellar crystals with interlocking structure initially. Then the coating transformed into seaweed-like and nano/micro-sized crystals along the depth direction of the coating. The coatings showed seaweed-like morphology as the deposition current density was less than 20mA. With the less current density, the coating became more homogenous. However, the coating was fiakiness crysal, with needlike crystal stacked upside as the current density reached to 20mA/cm2. The coating weight was improved gradually when the current density increased from 2.5mA/cm2 to 10mA/cm2, then reduced with the increasing current density in the range of 10 to 20mA/cm2.

EFFECT OF ETCHING TIME ON OPTICAL AND MORPHOLOGICAL FEATURES OF N-TYPE POROUS SILICON PREPARED BY PHOTO-ELECTROCHEMICAL METHOD

2016 ◽  
Vol 78 (3) ◽  
Author(s):  
Asad A. Thahe ◽  
Noriah Bidin ◽  
Mohammed A. Al-Azawi ◽  
Naser M. Ahmed
Keyword(s):  
Porous Silicon ◽  
Gravimetric Method ◽  
Constant Current ◽  
Etching Time ◽  
Absorption Data ◽  
Time Duration ◽  
Constant Current Density ◽  
Force Microscopy ◽  
Atomic Force ◽  
Structure Properties

Achieving efficient visible photoluminescence from porous-silicon (PSi) is demanding for optoelectronic and solar cells applications. Improving the absorption and emission features of PSi is challenging. Photo-electro-chemical etching assisted formation of PSi layers on n-type (111) silicon (Si) wafers is reported. Samples are prepared at constant current density (~30 mA/cm2) under varying etching times of 10, 15, 20, 25, and 30 min. The influence of etching time duration on the growth morphology and spectral properties are inspected. Room temperature photoluminescence (PL) measurement is performed to determine the optical properties of as-synthesized samples. Sample morphologies are imaged via Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM). The thickness and porosity of the prepared samples are estimated using the gravimetric method. The emission and absorption data is further used to determine the samples band gap and electronic structure properties. Results and analyzed, interpreted with different mechanisms and compared.  

Effect of Water on the IR Properties of Mg2+ Intercalated Electrochromic Nb2O5 Thin Films

2006 ◽  
Vol 972 ◽  
Author(s):  
Gargi Agarwal ◽  
G B Reddy
Keyword(s):  
Thin Films ◽  
Aqueous Solution ◽  
Water Content ◽  
Current Density ◽  
Sol Gel ◽  
Constant Current ◽  
Cyclic Stability ◽  
Constant Current Density ◽  
Effect Of Water ◽  
Ftir Studies

AbstractSol-gel derived Nb2O5 thin films were intercalated with Mg2+,using the non-aqueous solution of Mg(ClO4)2 in propylene carbonate (pc) as the electrolyte. 2% and 4% ( volume %) water was added to the electrolyte to study the effect of water on the electrochromic properties of Nb2O5. This paper presents the changes in optical and structural properties of the intercalated films with and without water in the electrolyte. The ratio (x) of the Mg2+ and Nb atoms has been controlled by optimizing the intercalation duration under a constant current density. The fall in transmittance on intercalation (for x= 0.8) increased by 15% with 4% water in the electrolyte, compared to the film intercalated without water. FTIR studies show that water is incorporated in the films on intercalation and small quantities of Mg(OH)2 and Nb-OH are formed along with Mg-O-Nb bonds. The presence of water in electrolyte decreases water content in the films and enhances the formation of Mg(OH)2, Mg-O-Nb and Nb-OH bonds. The recovery of Mg2+ on deintercalation is slightly reduced in presence of water in the electrolyte. The cyclic stability of the films intercalated without water is more than that of the films intercalated in presence of water.

Impedance Measurements to Determine the Influence of Fluoride at Platinum Anodes During the Formation of Peroxodisulfate

1995 ◽  
Vol 50 (11) ◽  
pp. 1717-1722
Author(s):  
Irene Scheler ◽  
Dietrich W. Wabner
Keyword(s):  
Current Density ◽  
Constant Current ◽  
Anode Surface ◽  
Impedance Spectra ◽  
Double Layer Capacitance ◽  
Constant Current Density ◽  
Impedance Measurements ◽  
Double Function ◽  
Galvanostatic Conditions ◽  
Electrolyte Resistance

The electrode reactions at platinum anodes in 1.5 M H2SO4 + 2.3 M (NH4)2SO4 solution with and without addition of NaF (0.5 M) have been examined. Impedance spectra between 1 to 100.000 Hz were measured under galvanostatic conditions. Electrolyte, polarization, chargetransfer resistance (RD), double-layer capacitance (CD) and inductance (L) were determined.For a constant current density, fluoride causes an increase o f CD and a decrease of RD. At a certain potential (measured and corrected by the electrolyte resistance) CD nearly remains the same with and without fluoride, whereas RD is slightly increased by fluoride.This behaviour is explained by the double function o f the fluoride: It is adsorbed on the anode surface and causes an increase o f the real current density on the surface. Simultaneously, the evolution o f oxygen is hindered by fluoride.

scholarly journals Ceftriaxone Degradation in the Presence of Sodium Halides Investigated by Electrochemical Methods Assisted by UV-Vis Spectrophotometry

2021 ◽  
Vol 11 (4) ◽  
pp. 1376
Author(s):  
Bogdan Tutunaru ◽  
Adriana Samide ◽  
Simona Iordache ◽  
Cristian Tigae ◽  
Andreea Simionescu ◽  
...  
Keyword(s):  
Cyclic Voltammetry ◽  
Current Density ◽  
Platinum Electrode ◽  
Active Species ◽  
Constant Current ◽  
Fluoride Ions ◽  
Constant Current Density ◽  
Iodide Ions ◽  
Transformation Reaction ◽  
Sodium Halides

The electrochemical stability of ceftriaxone (CFTX), belonging to the third generation of cephalosporin antibiotics, was studied by electrochemical measurements recorded on a platinum electrode (Pt) in aqueous solutions containing sodium halides. The electrochemical behavior of ceftriaxone was investigated by cyclic voltammetry (CV) and constant current density electrolysis assisted by UV-Vis spectrophotometry. Cyclic voltammetry highlighted that the addition of CFTX in sodium halide solutions leads to significant changes in the hysteresis characteristics due to specific interactions with active species from electrolytes, as well as with the platinum electrode surface. After CV, when an exterior electric stimulus in short time (40 s) was applied, the UV-Vis spectra illustrated that CFTX is stable in the presence of F− ions, it is electro(degraded/transformed) in the presence of Cl− and Br− ions and interacts instantly with I− species. Electrolysis at constant current density confirms the results obtained from cyclic voltammetry, showing that (i) in the presence of fluoride ions CFTX gradually decomposes, but not completely, in about 60 min, without identifying a reaction product; (ii) chloride and bromide ions determine the almost complete CFTX electro(degradation/transformation) in 10 and 5 min, respectively, with completion of the electro-transformation reaction after 60 and 30 min, respectively; (iii) instantaneous interactions between CFTX and the iodide ions occurred.

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