Titanium dioxide films were formed on quartz and crystalline p-Si (100) substrates by DC reactive magnetron sputtering method. Pure titanium target was sputtered at a constant oxygen partial pressure of 5x10-2 Pa, and at different sputtering powers in the range 80 – 200 W. The as-deposited films were annealed in air for 1 hour at 1023 K. The deposited films were characterized by studying the surface morphology by atomic force microscopy (AFM), electrical and dielectric properties from current-voltage and capacitance-voltage measurements. Atomic force micrographs of the films showed that the Rrms and Ra increased with the increase of sputter power from 80 to 200 W. The leakage current density was increased by increasing the sputtering power.
Structural, Dielectric and Optical properties of Sputtered TiO2 nano-filmsIOSR Journals
Thin films of TiO2 were deposited on quartz and p-Si (100) substrates held at room temperature by sputtering of titanium target at various sputter powers in the range 80 - 200 W. The as-deposited films were annealed in air for an hour at 1023 K. The annealed films were characterized by using Fourier transform infra red spectroscopy, X-ray diffraction, Surface morphology, dielectric and optical properties. The deposition rate of the films increased from 1.26 to 6.66 nm/min. with increase of sputter power from 80 to 200 W. TiO2 films formed at sputter power of 80 W and annealed at 1023 K were polycrystalline in nature with anatase phase crystallite size of 40 nm, dielectric constant of 10, optical band gap of 3.65 eV and refractive index 2.35.
Effect of Nanoporous Anodic Aluminum Oxide (AAO) Characteristics On Solar Abs...A Behzadmehr
Nanoporous anodic aluminum oxide (AAO) has been used in many different fields of science and technology, due to its great structural characteristics. Solar selective surface is an important application of this type porous material. This paper investigates the effect of nanoporous AAO properties, including; film thickness, pore area percentage and pore diameter, on absorption spectra in the range of solar radiation. The parameters were verified individually depending on anodization condition, and the absorption spectra were characterized using spectrophotometer analysis. The results showed that the absorptivity was increased with growth of the film thickness. Furthermore, increasing the pore diameter shifted the absorption spectra to the right range, and vice versa. The investigation revealed the presence of an optimum pore area percentage around 14% in which the absorptivity was at its maximum value.
Effect of Exchangeable Cations on Bentonite Swelling Characteristics of Geosy...drboon
Geosynthetic clay liners (GCLs) are thin hydraulic barriers which contain the bentonite sandwiched between geotextiles or geomembrane. Bentonite swelling is a very common phenomenon observed in GCLs. It is one of the major causes for permeability reduction in hydraulic barriers. The aim of this study is to characterize the swelling behavior of bentonite in GCLs by exchangeable cations. X-ray diffraction test and scanning electron microscopy were used to quantify the swelling characteristics of this bentonite under contact with salt solutions, as in the hydraulic barriers. The results from X-ray diffraction test showed that the presence of clay minerals was swelling montmorillonite. The swell volume of bentonite decreases with increasing valence of cations. In the case of the same valence the free swell volume of bentonite increased with decreasing concentration of permeant liquids. From another test, the scanning electron microscopy, it can be seen that the bentonite appears as corn flake like crystals for air-dried bentonite. However, specimen permeated with salt solutions, the clay has become more porous and fluffy and porous size seemed to be diminished.
Rosa alejandra lukaszew a review of the thin film techniques potentially ap...thinfilmsworkshop
SRF is a surface phenomenon where only ~10 penetration depths are needed (l=40 nm for niobium), thus it has been recognized for some time now that it would be economically convenient to use thin film coated cavities. But problems arise with defects within 1 or 2 l of the surface or on the surface, and insufficient attention has been paid to this topic, including trapping of impurities like oxygen in defects as well as surface roughness enabling magnetic field pinning sites. Earlier attempts at CERN applied standard sputter PVD methods, but the grain size for the CERN Nb/Cu films was 100 nm, which is 10,000 times smaller than for conventional SRF cavities with the ensuing problems that appear at grain boundaries. Thus, these prior attempts showed higher surface resistance and worst Q-slope than bulk. I will review more modern approaches using higher energetic PVD methods for thin film deposition which offer promise to achieve thin films with improved superconducting performance.
This is a power point presentation of project work on preparing Zinc oxide thin films by using SILAR technique and CBD technique and studying its characteristics.
Structural, Dielectric and Optical properties of Sputtered TiO2 nano-filmsIOSR Journals
Thin films of TiO2 were deposited on quartz and p-Si (100) substrates held at room temperature by sputtering of titanium target at various sputter powers in the range 80 - 200 W. The as-deposited films were annealed in air for an hour at 1023 K. The annealed films were characterized by using Fourier transform infra red spectroscopy, X-ray diffraction, Surface morphology, dielectric and optical properties. The deposition rate of the films increased from 1.26 to 6.66 nm/min. with increase of sputter power from 80 to 200 W. TiO2 films formed at sputter power of 80 W and annealed at 1023 K were polycrystalline in nature with anatase phase crystallite size of 40 nm, dielectric constant of 10, optical band gap of 3.65 eV and refractive index 2.35.
Effect of Nanoporous Anodic Aluminum Oxide (AAO) Characteristics On Solar Abs...A Behzadmehr
Nanoporous anodic aluminum oxide (AAO) has been used in many different fields of science and technology, due to its great structural characteristics. Solar selective surface is an important application of this type porous material. This paper investigates the effect of nanoporous AAO properties, including; film thickness, pore area percentage and pore diameter, on absorption spectra in the range of solar radiation. The parameters were verified individually depending on anodization condition, and the absorption spectra were characterized using spectrophotometer analysis. The results showed that the absorptivity was increased with growth of the film thickness. Furthermore, increasing the pore diameter shifted the absorption spectra to the right range, and vice versa. The investigation revealed the presence of an optimum pore area percentage around 14% in which the absorptivity was at its maximum value.
Effect of Exchangeable Cations on Bentonite Swelling Characteristics of Geosy...drboon
Geosynthetic clay liners (GCLs) are thin hydraulic barriers which contain the bentonite sandwiched between geotextiles or geomembrane. Bentonite swelling is a very common phenomenon observed in GCLs. It is one of the major causes for permeability reduction in hydraulic barriers. The aim of this study is to characterize the swelling behavior of bentonite in GCLs by exchangeable cations. X-ray diffraction test and scanning electron microscopy were used to quantify the swelling characteristics of this bentonite under contact with salt solutions, as in the hydraulic barriers. The results from X-ray diffraction test showed that the presence of clay minerals was swelling montmorillonite. The swell volume of bentonite decreases with increasing valence of cations. In the case of the same valence the free swell volume of bentonite increased with decreasing concentration of permeant liquids. From another test, the scanning electron microscopy, it can be seen that the bentonite appears as corn flake like crystals for air-dried bentonite. However, specimen permeated with salt solutions, the clay has become more porous and fluffy and porous size seemed to be diminished.
Rosa alejandra lukaszew a review of the thin film techniques potentially ap...thinfilmsworkshop
SRF is a surface phenomenon where only ~10 penetration depths are needed (l=40 nm for niobium), thus it has been recognized for some time now that it would be economically convenient to use thin film coated cavities. But problems arise with defects within 1 or 2 l of the surface or on the surface, and insufficient attention has been paid to this topic, including trapping of impurities like oxygen in defects as well as surface roughness enabling magnetic field pinning sites. Earlier attempts at CERN applied standard sputter PVD methods, but the grain size for the CERN Nb/Cu films was 100 nm, which is 10,000 times smaller than for conventional SRF cavities with the ensuing problems that appear at grain boundaries. Thus, these prior attempts showed higher surface resistance and worst Q-slope than bulk. I will review more modern approaches using higher energetic PVD methods for thin film deposition which offer promise to achieve thin films with improved superconducting performance.
This is a power point presentation of project work on preparing Zinc oxide thin films by using SILAR technique and CBD technique and studying its characteristics.
Novel effects can occur in materials when structures are formed with sizes comparable to any one of many possible length scales, such as the de Broglie wavelength of electrons, or the optical wavelengths of high energy photons. In these cases quantum mechanical effects can dominate material properties. One example is quantum confinement where the electronic properties of solids are altered with great reductions in particle size. The optical properties of nanoparticles, e.g. fluorescence, also become a function of the particle diameter. This effect does not come into play by going from macrosocopic to micrometer dimensions, but becomes pronounced when the nanometer scale is reached.
Electrochemical Supercapacitive Performance of Sprayed Co3O4 ElectrodesIJERA Editor
Nanocrystalline cobalt oxide (Co3O4) thin film electrodes were fabricated by spray pyrolysis method on conducting fluorine doped tin oxide (FTO) substrates using ammonia complexed with cobalt chloride (CoCl2. 6H2O) solution. The structural and morphological properties of Co3O4electrodes were studied using X-ray diffraction (XRD) and scanning electron microscopy (SEM).The surface morphology study showed the film formation of porous surface with clusters. The electrochemical supercapacitive properties ofCo3O4 electrodes were evaluated using cyclic voltammetry and galvanostatic charge-discharge method. The Co3O4electrodes showed maximum specific capacitance of 168 F/g in 1 M aqueous KOH electrolyte at the scan rate of 20 mV/s. The maximum specific energy and specific power of the cell are 2.2Wh/kg and 0.23 kW/kg, respectively.
Process flow of spray pyrolysis techniqueIOSR Journals
The chemical spray pyrolysis technique (SPT) has been, throughout last 3 decades, one amongst the most important techniques to deposit a large type of materials in thin film kind. The prime requisite for getting sensible quality thin film is that the optimization of propaedeutic conditions viz. substrate temperature, spray rate, concentration of solution etc. However, in recent years a stress has been given to a range of atomization techniques like supersonic nebulisation, improved spray reaction, corona spray transformation, electricity spray transformation and microchip primarily based spray transformation. This is often the foremost crucial parameter because it permits management over the scale of the droplets and their distribution over the preheated substrates. An intensive review of thin film materials ready throughout the last ten years is given to demonstrate the flexibility of the chemical SPT. the assorted conditions to get thin films of metal compound, metallic mineral oxides, binary, ternary and quaternary chalcogenides and superconducting oxides are given. The consequences of precursor, dopants, substrate temperature, post tempering treatments, answer concentration etc., on the physico-chemical properties of those films are given likewise. It’s discovered that the properties of thin films rely significantly on the propaedeutic conditions. The properties of the thin film will be simply tailored by adjusting or optimizing these conditions that successively are appropriate for a specific application.
Change the name and enjoy the File on Synthesis of nano materials. It is a really brief file can be used in small level presentation eg for the university students amd etc in educational field
Synthesis, Characterization of ZnS nanoparticles by Coprecipitation method us...IOSR Journals
ZnS nanoparticles are prepared by coprecipitation method using various capping agents like PVP (polyvinylpyrrolidone), PVA (polyvinylalcohol) and PEG-4000 (polyethyleneglycol). These are characterized by UV-Visible spectra, X-ray diffraction (XRD) studies, Fourier Transform Infra-red spectra (FTIR) and Transmission electron microscopy (TEM). UV-Visible absorption spectra are used to find the optical band gap and the values obtained have been found to be in the range of 3.80-4.00eV. The particle size of nanoparticles calculated from XRD pattern has been in the range of 2-4 nm. It is also observed that the particle size of nanoparticle is affected by the nature of capping agent. Photo catalytic degradation of xylenol orange (XO) by the nanoparticles shows that these act as photo catalysts under sunlight irradiation. The XO dye was degraded more than 87.24, 83.42 and 73.05% in the presence of PEG-4000, PVA and PVP capped ZnS nanoparticles in 120, 150 and 180 min. respectively. The kinetics of catalyzed by synthesized ZnS nanoparticles with XO dye follows pseudo-first order kinetics with reasonable apparent rate constants.
Novel effects can occur in materials when structures are formed with sizes comparable to any one of many possible length scales, such as the de Broglie wavelength of electrons, or the optical wavelengths of high energy photons. In these cases quantum mechanical effects can dominate material properties. One example is quantum confinement where the electronic properties of solids are altered with great reductions in particle size. The optical properties of nanoparticles, e.g. fluorescence, also become a function of the particle diameter. This effect does not come into play by going from macrosocopic to micrometer dimensions, but becomes pronounced when the nanometer scale is reached.
Electrochemical Supercapacitive Performance of Sprayed Co3O4 ElectrodesIJERA Editor
Nanocrystalline cobalt oxide (Co3O4) thin film electrodes were fabricated by spray pyrolysis method on conducting fluorine doped tin oxide (FTO) substrates using ammonia complexed with cobalt chloride (CoCl2. 6H2O) solution. The structural and morphological properties of Co3O4electrodes were studied using X-ray diffraction (XRD) and scanning electron microscopy (SEM).The surface morphology study showed the film formation of porous surface with clusters. The electrochemical supercapacitive properties ofCo3O4 electrodes were evaluated using cyclic voltammetry and galvanostatic charge-discharge method. The Co3O4electrodes showed maximum specific capacitance of 168 F/g in 1 M aqueous KOH electrolyte at the scan rate of 20 mV/s. The maximum specific energy and specific power of the cell are 2.2Wh/kg and 0.23 kW/kg, respectively.
Process flow of spray pyrolysis techniqueIOSR Journals
The chemical spray pyrolysis technique (SPT) has been, throughout last 3 decades, one amongst the most important techniques to deposit a large type of materials in thin film kind. The prime requisite for getting sensible quality thin film is that the optimization of propaedeutic conditions viz. substrate temperature, spray rate, concentration of solution etc. However, in recent years a stress has been given to a range of atomization techniques like supersonic nebulisation, improved spray reaction, corona spray transformation, electricity spray transformation and microchip primarily based spray transformation. This is often the foremost crucial parameter because it permits management over the scale of the droplets and their distribution over the preheated substrates. An intensive review of thin film materials ready throughout the last ten years is given to demonstrate the flexibility of the chemical SPT. the assorted conditions to get thin films of metal compound, metallic mineral oxides, binary, ternary and quaternary chalcogenides and superconducting oxides are given. The consequences of precursor, dopants, substrate temperature, post tempering treatments, answer concentration etc., on the physico-chemical properties of those films are given likewise. It’s discovered that the properties of thin films rely significantly on the propaedeutic conditions. The properties of the thin film will be simply tailored by adjusting or optimizing these conditions that successively are appropriate for a specific application.
Change the name and enjoy the File on Synthesis of nano materials. It is a really brief file can be used in small level presentation eg for the university students amd etc in educational field
Synthesis, Characterization of ZnS nanoparticles by Coprecipitation method us...IOSR Journals
ZnS nanoparticles are prepared by coprecipitation method using various capping agents like PVP (polyvinylpyrrolidone), PVA (polyvinylalcohol) and PEG-4000 (polyethyleneglycol). These are characterized by UV-Visible spectra, X-ray diffraction (XRD) studies, Fourier Transform Infra-red spectra (FTIR) and Transmission electron microscopy (TEM). UV-Visible absorption spectra are used to find the optical band gap and the values obtained have been found to be in the range of 3.80-4.00eV. The particle size of nanoparticles calculated from XRD pattern has been in the range of 2-4 nm. It is also observed that the particle size of nanoparticle is affected by the nature of capping agent. Photo catalytic degradation of xylenol orange (XO) by the nanoparticles shows that these act as photo catalysts under sunlight irradiation. The XO dye was degraded more than 87.24, 83.42 and 73.05% in the presence of PEG-4000, PVA and PVP capped ZnS nanoparticles in 120, 150 and 180 min. respectively. The kinetics of catalyzed by synthesized ZnS nanoparticles with XO dye follows pseudo-first order kinetics with reasonable apparent rate constants.
IOSR Journal of Pharmacy and Biological Sciences(IOSR-JPBS) is an open access international journal that provides rapid publication (within a month) of articles in all areas of Pharmacy and Biological Science. The journal welcomes publications of high quality papers on theoretical developments and practical applications in Pharmacy and Biological Science. Original research papers, state-of-the-art reviews, and high quality technical notes are invited for publications.
Qualitative Chemistry Education: The Role of the TeacherIOSR Journals
Abstract: This paper discussed the role of a chemistry teacher towards improving the quality of education in Nigeria. The decline in the quality of education has been attributed to many factors. Some of these factors are unqualified teachers, examination malpractice,, lack of practical skills, method of classroom instruction, to mention but a few. The role of a chemistry teacher among others is to change the method of classroom instruction from lecture method to innovative learning strategy such as cooperative learning and concept mapping, and to make use of improvised materials in the absence of standard equipments . It also examine the problems associated with the fall in quality of education. Finally it is recommended that Government should ensure that adequate funds are released to train science teachers, since teachers are the main determinant of quality in Education.
Seismic Study and Spatial Variation of b-value in Northeast IndiaIOSR Journals
Study of recent seismicity and b-value estimation by Least Square and Maximum Likelihood Estimation methods in five tectonic blocks of Northeast India demarcates indo Burma Belt, Main Central Thrust, Main Boundary Thrust, Shilling Plateau, Mikir Hills and Kopili Lineament as active seismic source of the region. Spatial variation of b-value is observed by dividing the study area into 10×10 grids. Higher b-value contours depict the highly seismic area with structural heterogeneity, while lower b-value contours indicate the areas under high stress. b-values are observed in the range of 0.437 - 0.908 and mostly concentrated around 0.7, indicating high stress accumulation.
Influence of Thickness on Electrical and Structural Properties of Zinc Oxide ...paperpublications3
Abstract: Zinc Oxide (ZnO) thin films were prepared on corning (7059) glass substrates at a thickness of 75.5 and 130.5nm by RF sputtering technique. The deposition was carried out at room temperature after which the samples were annealed in open air at 1500C. The electrical and structural properties of these films were studied. The electrical properties of the films were monitored by four-point probe method while the structural properties were studied by X-ray diffraction (XRD). It was found that the electrical resistance of the films decreases with increase in the thickness of the films. The XRD analysis of the films showed that the films have a peak located at 〖34.31^0-34.35〗^0with hkl (002). Other parameters calculated include the stress ( ) and the grain size (D).
IJERA (International journal of Engineering Research and Applications) is International online, ... peer reviewed journal. For more detail or submit your article, please visit www.ijera.com
Optical and Electrical Properties of TiO2 Doped Fe2O3 Thin Film Prepared by S...IJAEMSJORNAL
In this work, iron oxide (Fe2O3) and titanium oxide (TiO2) doping (Fe2O3) thin films have been prepared by spray pyrolysis technique (SPT) on a glass substrate. We have studied the effects of various doping percentage of (TiO2) on (Fe2O3) optical and electrical properties. The optical parameters of the prepared films as absorbance, absorption coefficient, optical energy gap and refractive index have been calculated for all prepared films. D.C conductivity and Hall effect for all films are measured. The results showed that absorbance of prepared films decreases with increasing percentage of (TiO2) this lead to increase the energy gap and conductivity decreased with increasing of percentage of (TiO2) as well as the results showed throughout the study that all films have tow activation energy, its value increase with increasing of percentage of (TiO2). Hall effect measurement showed all films have n-type conductivity.
Photoelectrochemical characterization of titania photoanodes fabricated using...Arkansas State University
Design and fabrication of new electrodes for photo-electrolysis using a material that is photo-active, stable, corrosion resistant, and cost effective.
surface characteristics and electrochemical impedance investigation of spark-...mohammad fazel
In this study, the surface characteristic of oxide films on Ti-6Al-4V alloy formed by an anodic oxidation treatment at potentials higher than the breakdown voltage was evaluated.
Synthesis Of Nanostructured TiO2 Thin Films By Pulsed Laser Deposition (PLD) ...sarmad
Sarmad Sabih Al-Obaidi
Ali Ahmed Yousif
Abstract
In this work, nanostructured TiO2 thin films were grown by pulsed laser deposition (PLD) technique on glass substrates. TiO2 thin films then were annealed at 400-600 °C in air for a period of 2 hours. Effect of annealing on the structural and morphological were studied. Many growth parameters have been considered to specify the optimum conditions, namely substrate temperature (300 °C), oxygen pressure (10-2 Torr), laser fluence energy density (0.4 J/cm2), using double frequency Q-switching Nd:YAG laser beam (wavelength 532nm), repetition rate (1-6 Hz) and the pulse duration of 10 ns. The results of the X-ray test show that all nanostructures tetragonal are polycrystalline. These results show that grain size increase from 19.5 nm to 29.5 with the increase of annealing temperature. The XRD results also reveal that the deposited thin film, annealed at 400 °C of TiO2 have anatase phase. Thin films annealed at 500 °C and 600 °C have mixed anatase and rutile phases. Full Width at Half Maximum (FWHM) values of the (101) peaks of these films decrease from 0.450° to 0.301° with the increase of annealing temperature. Surface morphology of the thin films have been studied by using atomic force microscopes (AFM). AFM measurements confirmed that the films have good crystalline and homogeneous surface. The Root Mean Square (RMS) value of thin films surface roughness are increased with the increase of annealing temperature.
الخلاصة
على (PLD) النانویة بوساطة تقنیة ترسیب اللیزر النبضي (TiO في ھذا البحث، تم انماء أغشیة اوكسید التیتانیوم ( 2
الرقیقة من 400 الى 600 درجة مئویة في الھواء مدة ساعتین . ودرس تأثیر TiO قواعد زجاجیة. ومن ثم لدنت أغشیة 2
التلدین في الخصائص التركیبیة والطبوغرافیة. عوامل عدیدة لأنماء الأغشیة اخذت بنظر الاعتبار لتحدید الحالة المثلى مثل
0.4 ) باستخدام J/cm 10-2 ) ،كثافة طاقة الفیض اللیزري( 2 Torr) 300 ) ،ضغط الأوكسجین ºC) درجة حرارة القاعدة
532 بمعدل تكراریة - 1 nm التردد المضاعف للیزر النیدیمیوم- یاك الذي یعمل بتقنیة عامل النوعیة عند الطول الموجي
6 ھرتز) وامد نبضة 10 نانوثانیة. تظُھر نتائج فحوصات الأشعة السینیة أن جمیع التراكیب النانویة رباعیة متعددة )
التبلور. وان ھذه النتائج تظھر زیادة في حجم الحبیبات من 19.5 نانومتر الى 29.5 نانومترمع زیادة درجة حرارة التلدین.
نتائج الأشعة السینیة اظھرت ایضا ان الغشاء المرسب والملدن في 400 درجة مئویة لثنائي اوكسید
Correlation between the Interface Width and the Adhesion Strength of Copper F...IOSRJAP
The present study has been conducted in order to determine the influence of negative bias voltage applied to substrate on adhesion of copper films deposited on carbon steel substrates. The adhesion strength has been evaluated by the scratch test. Coatings were deposited by a DC magnetron sputtering system. The substrates were firstly mechanically polished and then ion-etched by argon ions prior to deposition. Adhesion was found to increase with the bias voltage. The critical load had a value of 9.5 g for an unbiased substrate and reached 18.5 g for a bias voltage of 600 V. Equally important, the interface width, measured using Auger electron spectroscopy, increased as a function of the bias voltage. The width of the interface is related to the time of ion milling in the Auger spectrometer. The size of this width is obtained from the Auger elemental depth profiles through measuring the depth of the interface coating/substrate. The width had a value of 335 min with a bias of 600 V whereas it didn't exceed 180 min when the substrate was unbiased. Therefore, the effect of the bias voltage was to expand the interface because of the diffusion phenomenon and physical mixing of materials at the interface. Moreover, the critical load increased with the increase of the interface width.
Dye Sensitized Solar Cells Incorporated with Tio2 -ZnO NanoparticlesScientific Review SR
We demonstrated an improvement in efficiency of Dye sensitized solar cells (DSSCs) decorated with
zinc oxide (ZnO) nanoparticles (NPs) through successive ionic layer adsorption and reaction (SILAR). A series of
ZnO with different SILAR cycles were synthesized on TiO
2 that has been pre-grown on fluorine tin oxide (FTO)
glass slides. The performance of DSSCs containing ZnO NPs was significantly affected. The photovoltaic (PV)
performance decreased with increasing number of SILAR cycles from two SILAR cycles to four SILAR cycles,
the best performance was achieved using the anodes prepared with two SILAR cycles. The best cell shows a
conversion efficiency (η) of 0.0064 %. The cell exhibits ~ 2.13 improvement over the performance (0.0030 %) of
bare FTO-based device. The related PV performance enhancement mechanism is discussed
Studies on in-Doped Zno Transparent Conducting thin FilmsIJRESJOURNAL
ABSTRACT: In this manuscript we have investigated the influences of indium dopants on zinc oxide (ZnO) thin films regarding physico-chemical properties for application in modern conducting devices. As a starting material, Indium (III) chloride, and Zn(CH3COO)2⋅2H2O were used. The complex TSDC spectrum was obtained by submitting the sample to a constant electrical field Ep = 10M V/m during 2 min at a varing polarization temperature of Tmax = 1500C. A minimal sheet resistance with electrical resistivity as low in the range of 10-3 Ω·cm was found for this thin film.
We investigate thermoelastic stresses in titanium dioxide films on a sapphire
substrate that arise during thermal annealing. The effect of thermal processes on
thermoelastic stresses in titanium dioxide films has been studied experimentally. The
obtained experimental results are in good agreement with the theoretical calculations
of mechanical stresses in a titanium dioxide film
Introduction:
RNA interference (RNAi) or Post-Transcriptional Gene Silencing (PTGS) is an important biological process for modulating eukaryotic gene expression.
It is highly conserved process of posttranscriptional gene silencing by which double stranded RNA (dsRNA) causes sequence-specific degradation of mRNA sequences.
dsRNA-induced gene silencing (RNAi) is reported in a wide range of eukaryotes ranging from worms, insects, mammals and plants.
This process mediates resistance to both endogenous parasitic and exogenous pathogenic nucleic acids, and regulates the expression of protein-coding genes.
What are small ncRNAs?
micro RNA (miRNA)
short interfering RNA (siRNA)
Properties of small non-coding RNA:
Involved in silencing mRNA transcripts.
Called “small” because they are usually only about 21-24 nucleotides long.
Synthesized by first cutting up longer precursor sequences (like the 61nt one that Lee discovered).
Silence an mRNA by base pairing with some sequence on the mRNA.
Discovery of siRNA?
The first small RNA:
In 1993 Rosalind Lee (Victor Ambros lab) was studying a non- coding gene in C. elegans, lin-4, that was involved in silencing of another gene, lin-14, at the appropriate time in the
development of the worm C. elegans.
Two small transcripts of lin-4 (22nt and 61nt) were found to be complementary to a sequence in the 3' UTR of lin-14.
Because lin-4 encoded no protein, she deduced that it must be these transcripts that are causing the silencing by RNA-RNA interactions.
Types of RNAi ( non coding RNA)
MiRNA
Length (23-25 nt)
Trans acting
Binds with target MRNA in mismatch
Translation inhibition
Si RNA
Length 21 nt.
Cis acting
Bind with target Mrna in perfect complementary sequence
Piwi-RNA
Length ; 25 to 36 nt.
Expressed in Germ Cells
Regulates trnasposomes activity
MECHANISM OF RNAI:
First the double-stranded RNA teams up with a protein complex named Dicer, which cuts the long RNA into short pieces.
Then another protein complex called RISC (RNA-induced silencing complex) discards one of the two RNA strands.
The RISC-docked, single-stranded RNA then pairs with the homologous mRNA and destroys it.
THE RISC COMPLEX:
RISC is large(>500kD) RNA multi- protein Binding complex which triggers MRNA degradation in response to MRNA
Unwinding of double stranded Si RNA by ATP independent Helicase
Active component of RISC is Ago proteins( ENDONUCLEASE) which cleave target MRNA.
DICER: endonuclease (RNase Family III)
Argonaute: Central Component of the RNA-Induced Silencing Complex (RISC)
One strand of the dsRNA produced by Dicer is retained in the RISC complex in association with Argonaute
ARGONAUTE PROTEIN :
1.PAZ(PIWI/Argonaute/ Zwille)- Recognition of target MRNA
2.PIWI (p-element induced wimpy Testis)- breaks Phosphodiester bond of mRNA.)RNAse H activity.
MiRNA:
The Double-stranded RNAs are naturally produced in eukaryotic cells during development, and they have a key role in regulating gene expression .
This pdf is about the Schizophrenia.
For more details visit on YouTube; @SELF-EXPLANATORY;
https://www.youtube.com/channel/UCAiarMZDNhe1A3Rnpr_WkzA/videos
Thanks...!
THE IMPORTANCE OF MARTIAN ATMOSPHERE SAMPLE RETURN.Sérgio Sacani
The return of a sample of near-surface atmosphere from Mars would facilitate answers to several first-order science questions surrounding the formation and evolution of the planet. One of the important aspects of terrestrial planet formation in general is the role that primary atmospheres played in influencing the chemistry and structure of the planets and their antecedents. Studies of the martian atmosphere can be used to investigate the role of a primary atmosphere in its history. Atmosphere samples would also inform our understanding of the near-surface chemistry of the planet, and ultimately the prospects for life. High-precision isotopic analyses of constituent gases are needed to address these questions, requiring that the analyses are made on returned samples rather than in situ.
Professional air quality monitoring systems provide immediate, on-site data for analysis, compliance, and decision-making.
Monitor common gases, weather parameters, particulates.
Nutraceutical market, scope and growth: Herbal drug technologyLokesh Patil
As consumer awareness of health and wellness rises, the nutraceutical market—which includes goods like functional meals, drinks, and dietary supplements that provide health advantages beyond basic nutrition—is growing significantly. As healthcare expenses rise, the population ages, and people want natural and preventative health solutions more and more, this industry is increasing quickly. Further driving market expansion are product formulation innovations and the use of cutting-edge technology for customized nutrition. With its worldwide reach, the nutraceutical industry is expected to keep growing and provide significant chances for research and investment in a number of categories, including vitamins, minerals, probiotics, and herbal supplements.
Body fluids_tonicity_dehydration_hypovolemia_hypervolemia.pptx
Surface Morphological and Electrical Properties of Sputtered Tio2 Thin Films
1. IOSR Journal of Applied Physics (IOSR-JAP)
e-ISSN: 2278-4861.Volume 4, Issue 1 (May. - Jun. 2013), PP 25-29
www.iosrjournals.org
www.iosrjournals.org 25 | Page
Surface Morphological and Electrical Properties of Sputtered
Tio2 Thin Films
M.Thaidun1x
, B.Venkata Rao1
, L.Raja Mohan Reddy1
Department of Physics,Loyola Degree College (YSRR),Pulivendla,A.P,India.516390
Abstract: - Titanium dioxide films were formed on quartz and crystalline p-Si (100) substrates by DC reactive
magnetron sputtering method. Pure titanium target was sputtered at a constant oxygen partial pressure of 5x10-
2
Pa, and at different sputtering powers in the range 80 – 200 W. The as-deposited films were annealed in air
for 1 hour at 1023 K. The deposited films were characterized by studying the surface morphology by atomic
force microscopy (AFM), electrical and dielectric properties from current-voltage and capacitance-voltage
measurements. Atomic force micrographs of the films showed that the Rrms and Ra increased with the increase of
sputter power from 80 to 200 W. The leakage current density was increased by increasing the sputtering power.
Keyword: - AFM, DC sputtering technique, Titanium dioxide thin film.
I. Introduction
For a long time, TiO2
thin films have got attention in either as an optical material or as a protective
layer for very large scale integrated circuits, because of their high refractive index, excellent optical
transmittance and good semiconductor properties (3eV gap), high dielectric constant, very good wear resistance,
a high chemical resistance against solvents and acids and stability [1-3]. Due to these special properties, TiO2
has become the subject of many investigations for applications in optical coatings, microelectronic devices and
protective layers. In the last decade, titanium dioxide has also attracted a great deal of interest due to its
photocatalytic behavior [4, 5]. The decomposition of organic compounds on the surface of TiO2 and the
reduction of the contact angle between water and the surface of TiO2 under UV irradiation results in self-
cleaning and anti-fogging effects [6]. It is well known that titania exhibits three distinct crystalline forms apart
from the amorphous form: an orthorhombic one, the brookite and two tetragonal phases, the anatase and the
rutile [7, 8]. The occurrence of anatase and rutile phase depends significantly on the method and conditions of
deposition as well as the substrate temperature [9]. Each crystalline form is convenient for a different purpose.
While rutile is mainly desirable for optical applications, anatase has more efficient photocatalytic properties.
Which structure is formed during the fabrication of TiO2 thin films depends on the deposition technique, the
deposition parameters and the deposition configuration.
TiO2 films were prepared by various methods, such as chemical vapour deposition, pulsed laser
deposition, sol-gel deposition, spray pyrolysis, plasma enhanced chemical vapour deposition and DC/RF
magnetron sputtering [10-14]. However for most deposition techniques, a high temperature by use of substrate
heating or post-deposition annealing is required for the growth of anatase or rutile phases of TiO2 thin films
instated of amorphous films. Compared to other deposition methods, DC Magnetron sputtering technique has
significant importance because it enables control of the structure, good adhesion on the substrate of deposited
films, high density and homogeneity, composition and properties of TiO2 films by adjusting the deposition
conditions. This results in high quality thin films with thickness uniformity over large areas and well controlled
stoichiometry.
II. Experimental
Thin films of TiO2 were deposited on silicon and quartz substrates by sputtering of titanium target
under various oxygen partial pressures using the DC modes. The TiO2 films were deposited at oxygen partial
pressure of 5x10-2
Pa and at a fixed substrate temperature of 303 K and at different sputtering powers in the
range 80 – 200 W. The as-deposited films were annealed in air at 750o
C for 1 hour. The TiO2 films were
deposited on p-type silicon substrate by DC magnetron sputtering and the top electrode of aluminum was
deposited using Hind High Vacuum coating unit by vacuum evaporation. The Si wafers were placed in Teflon
container. Insoluble organic contaminants in the wafer can be removed by immersing the wafers in the organic
clean solution, which is maintained (5:1:1, H2O: H2O2: NH4OH) for 10 minutes. Removed carrier form the
organic clean solution and rinse wafer in the deionized water for one minute. Submerge the carrier with wafer in
the oxide strip solution (50:1, H2O:HF) for 15 seconds in order to remove silicon dioxide that may be
accumulated as a result of organic clean. Then remove carrier from the bath and rinse the wafer in deionized
water for one minute. Finally removed the substrates from the substrate carrier contained deionized water and
2. Surface Morphological and Electrical Properties of Sputtered TiO2 thin films
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blown dry with nitrogen. The deposited films were characterized by studying the surface morphology by atomic
force microscopy (AFM), electrical and dielectric properties from current-voltage and capacitance-voltage
measurements.
III. Results and Discussion
The dependence of deposition rate of the TiO2 films on the sputtering power is shown in figure 3.1. The
deposition rate of the films at a low sputtering power of 50 W was 1.26 nm/min. At low sputtering powers, the
target current was low which attributed to the lower argon ion bombardment on the target surface due to lower
ion flux results in low sputtering yield. The deposition rate of the films increased from 1.26 to 6.66 nm/ min
with the increase of sputter power from 80 to 200 W. At higher sputtering powers, high argon ion flux generally
resulted in substantial ion bombardment on the target with high kinetic energy which increased the probability
that the impact of incident ions will eject more target atoms [15].
The surface morphological studies of the sputtered TiO2 thin films were carried out by using atomic
force microscope. Figure 3.2 shows the atomic force micrographs of the TiO2 films deposited at different
sputtering powers. The micrographs showed that the TiO2 films deposited at low sputtering power has a
smoother and less dense in structure. At low sputtering powers, the adatoms with low kinetic energy result in
negligible surface diffusion. When sputtering power increased to 120 W, the TiO2 films appeared to be
continuous with fine sized grains might be due to presence of mixed phase. As the sputtering power increased to
160 W, the grain size of the films increased. The surface diffusion of the adatoms was enhanced with the
momentum transfer to the growing surface resulted an increase in the grain size present in the films. The
enhancement in crystallinity of the films was achieved at higher sputtering power of 200 W due to larger impact
energy of the bombarding particles, which lead to better surface mobility. The higher the sputtering power, the
more likely the film formed was of continuous and with higher crystallinity due to sufficient high adatom
mobility which improved the surface diffusion. The grain size of the TiO2 films increased as the sputtering
power increased. The increase in the grain size was a result of bombardment to the growth surface by more
energetic particles with increasing sputtering power was also reported by Song et al. [16].
Figure 3.3 shows the typical leakage current characteristics of the MOS (Al/TiO2/p-Si) structured
capacitors for negative and positive applied voltages formed at different sputter powers. For the current –
voltage measurements, a step time of 1s and a step voltage of 0.1 V was used. It is seen from the figure that the
leakage current density increased with the increase of sputter power. The minimum leakage current density
achieved with sputter power of 80 W at a gate bias voltage of 1.5 V was 1.30x10-8
A/cm2
and it was increased to
1.39x10-6
A/cm2
by increasing the sputter power to 200 W. The increase in leakage current density with
sputtering power was due to the increase in oxygen defects in the TiO2 films and also increases in the structural
defects. Huang et al. [17] was also observed the increase in leakage currents with the increase in sputter power
of MgTiO3 films.
Figure 3.4 shows the capacitance-voltage at different frequencies at different frequencies for
Al/TiO2/p-Si capacitors formed at different sputtering powers in the range 80 – 200 W and annealed at 1023 K.
The capacitance of the TiO2 capacitors was decreased with the increase in frequency. The increase of
capacitance of the device at low frequencies depends on the ability of the electron concentration to follow the
applied signal. While the decrease of capacitance of the device at high frequencies, the charge at the interface
cannot follow an AC signal.
The capacitance–voltage measurements for TiO2 films formed at different sputtering powers were
shown in figure 3.5. The experimental characteristics are similar to normal C–V dependence, i.e. accumulation,
depletion and inversion could be easily recognized (Fig. 3.5). For negatively biased structure, negative electron
charge at the gate is balanced by positive hole charges accumulated near the surface of the semiconductor (p-
type). In an ideal MOS system capacitance (C) measured in this accumulation state is equal to oxide capacitance
Cox = 2794x10-12
F at 80 W. Switching the bias voltage into positive direction makes semiconductor surface
depleted from the holes, so that the additional capacitance of space charge layer Cs, is serially connected to Cox.
Moreover, the positive gate biasing makes that at low frequency conditions inversion of the conduction type
occurs. In the strong inversion conditions, potential changes at the gate are determined by the presence of
electrons at the semiconductor metal interface. Thus, the total measured capacitance, similar to the accumulation
state, approach to the Cox. The capacitance of TiO2 films was decreased from 2794x10-12
to 1309x10-12
F with
the increase of sputter power from 80 to 200 W [17]. The capacitance of the TiO2 capacitors was increased due
to the decrease in the measured thickness of the films with the decrease of sputtering power. From the measured
capacitance and physical thickness, the dielectric constant (k) of the TiO2 films can be calculated. The dielectric
constant was calculated from the capacitance - voltage curves using the following formula,
C = kεoA / t (1)
Where C is the capacitance, k the dielectric constant of the material, εo the permittivity of free space (8.85x10-
3
fF/µm), A the area of the capacitor, and t the thickness of the dielectric. The dielectric constant of the TiO2
3. Surface Morphological and Electrical Properties of Sputtered TiO2 thin films
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films formed at sputter power of 80 W was 10 and it increased to 35 with the increase of sputtering power to
200 W. Figure 3.6 shows the dependence of dielectric constant on sputter power. The dielectric constant of the
films increased with the increase of sputter power. These annealed films at different sputter powers leads to
decrease of structural defects, and change the phase transformation from anatase to rutile phase, hence enhance
in the dielectric constant of the TiO2 films.
IV. FIGURES
Fig.3.1. Variation of deposition rate with sputter power of TiO2 films.
Fig.3.2. Atomic force micrographs of TiO2 films formed at: (a) 80, (b) 120, (c) 160 and (d) 200 W
4. Surface Morphological and Electrical Properties of Sputtered TiO2 thin films
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Fig. 3.3. I-V characteristics of TiO2 films formed at different sputter powers.
Fig. 3.4 Capacitance – Voltage curves of Al/TiO2/p-Si capacitors at different Frequencies.
Fig. 3.5 Capacitance – Voltage curves (at 1 MHz) of Al/TiO2/p-Si capacitors
5. Surface Morphological and Electrical Properties of Sputtered TiO2 thin films
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Fig. 3.6 Variation of dielectric constant with sputter powers
V. Conclusion
In conclusion, TiO2 films formed at sputter power of 80 W and annealed at 1023 K were
polycrystalline in nature with anatase phase, the grain size of the TiO2 films increased as the sputtering power
increased. The leakage current density and dielectric constant was increased by increasing the sputtering power.
References
[1] Y. Leprince-Wang, D. Souche, K. Yu-Zhang, S. Fisson, G. Vuye and J. Rivory, Thin Solid Films, 359 (2000) 171.
[2] P. Zeman and S. Takabayashi, Surface and Coatings Technology, 93 (2002) 153.
[3] L. Miao, P. Jin, K. Kaneko, A. Terai, N. Nabatova-Gabain and S. Tanemura, Applied Surface Science, 255 (2003) 212.
[5] R. Wang, K. Hashimoto, A. Fujishima, M. Chikuni, E. Kojima, A. Kitamura, M.Shimohigoshi and T. Watanabe, Nature, 388 (1997)
431.
[6] T. Watanabe, A. Nakajima, R. Wang, M. Minabe, S. Koizumi, A. Fujishima and K. Hashimoto, Thin Solid Films, 351 (1999) 260.
[7] K. Takagi, T. Makimoto, H. Hiraiwa and T. Negishi, J. Vac. Sci. Technol., A 19(6) (2001) 2931.
[8] S. Ben Amor, G. Baud, J. P. Besse and M. Jacquet, Materials Science and Engineering, B47 (1997) 110.
[9] J. Szczyrbowski, G. Bräuer, M. Ruske, J. Bartella, J. Schroeder and A. Zmelty, Surface and Coatings Technology, 112 (1999) 261.
[10] N. Martin, C. Rousselot, D. Rondot, F. Palmino and R. Mercier, Thin Solid Films, 300 (1997) 113.
[11] M. Takeuchi, N. Yamasaki, K. Tsujimaru, Chem. Lett., 35 (2006) 904.
[12] A. Verma, A.G. Joshi, A.K.Bakshi, S.M. Shivaprasad and S.A. Agnihotry, Appl. Surf. Sci., 252 (2006) 5131.
[13] I.Turkevych, Y. Pihosh, M. Goto, A.Kasahara, M. Tosa, S. kato, K. Takehana, T. Takamasu, G. Kido and N. Koguchi, Thin Solid
Films, 516 (2007) 2387.
[14] M. Vishwas, S.K. Sharma, K. Narshimha Reao, S. Mohan,K.V.A. Gowda and R.P.S. Chakradhar, Spectrochim. Acta, Part A 74
(2009) 839.
[15] Nirupama and S. Uthanna, J. Mater. Sci.: Mater. Electron., 21 (2010) 45.
[16] Y.S. Song, J.K. Park, T.W. Kin and C.W. Chung, Thin Solid Films, 467 (2004) 120.
[17] C.L. Huang and Y.B. Chen, J.Cryst. Growth, 285 (2005) 586.