Pub Date : 2014-02-27DOI: 10.4236/WJNSE.2014.41005
Xuyao Xu, Xiaosong Zhou, Lin Ma, Miaoyan Mo, Cuifen Ren, Rongkai Pan
Nanocrystalline TiO2 powders with high photocatalytic activity were prepared by one-step microemulsion-mediated hydrothermal method using tetrabutylorthotitanate (TiO(C4H9)4, TBOT) as precursor. The as-prepared TiO2 powders were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and the Brunauer-Emmett-Teller (BET) specific surface area measurements. The effects of the oil/water ratio and hydrothermal temperature on the microstructures and photocatalytic activity of the TiO2 powders were investigated. The results suggest that increasing the oil/water emulsion ratio significantly decreased the particle size of the as-prepared TiO2 powders and improved the photocatalytic activity. With hydrothermal temperature increasing, the average crystallite size increased and the photocatalytic activities of TiO2 powders decreased.
{"title":"One-Step Microemulsion-Mediated Hydrothermal Synthesis of Nanocrystalline TiO 2","authors":"Xuyao Xu, Xiaosong Zhou, Lin Ma, Miaoyan Mo, Cuifen Ren, Rongkai Pan","doi":"10.4236/WJNSE.2014.41005","DOIUrl":"https://doi.org/10.4236/WJNSE.2014.41005","url":null,"abstract":"Nanocrystalline TiO2 powders with high photocatalytic activity were prepared by one-step microemulsion-mediated hydrothermal method using tetrabutylorthotitanate (TiO(C4H9)4, TBOT) as precursor. The as-prepared TiO2 powders were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and the Brunauer-Emmett-Teller (BET) specific surface area measurements. The effects of the oil/water ratio and hydrothermal temperature on the microstructures and photocatalytic activity of the TiO2 powders were investigated. The results suggest that increasing the oil/water emulsion ratio significantly decreased the particle size of the as-prepared TiO2 powders and improved the photocatalytic activity. With hydrothermal temperature increasing, the average crystallite size increased and the photocatalytic activities of TiO2 powders decreased.","PeriodicalId":66816,"journal":{"name":"纳米科学与工程(英文)","volume":"4 1","pages":"29-34"},"PeriodicalIF":0.0,"publicationDate":"2014-02-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70878117","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2014-02-27DOI: 10.4236/WJNSE.2014.41002
Abdelaali Fargi, N. Hizem, A. Kalboussi, A. Souifi
Several methods of characterization of trap levels like I-V, C-V and transient spectroscopy (DLTS) were used to determine the accurate values of the activation energies of traps present in N+P junctions obtained after retrograde profile implantation of indium and boron on silicon. Four main traps located at Ev + 0.15 eV, Ev + 0.21 eV, Ev + 0.28 eV and Ev + 0.46 eV are reported. Shallow levels are also calculated from I-V characteristics. Concurrently, indium channel doped NMOSFETs are investigated showing the kink phenomenon. In order to discuss the relationship between the kink effect and the active indium trap level situated at 0.16 eV, the transient effects are studied by varying the integration time and the temperature. The effects of substrate polarization are also carried out showing the reduction of the kink with the bulk positive polarization.
利用I-V、C-V和瞬态光谱(dts)等几种表征陷阱能级的方法，确定了铟和硼在硅上逆行注入后N+P结中陷阱活化能的准确值。四个主要的陷阱分别位于Ev + 0.15 Ev, Ev + 0.21 Ev, Ev + 0.28 Ev和Ev + 0.46 Ev。浅电平也从I-V特性计算。同时，研究了掺杂铟沟道的nmosfet，发现了扭结现象。为了探讨结扭效应与处于0.16 eV的活性铟阱能级之间的关系，通过改变积分时间和温度研究了结扭效应的瞬态效应。基片极化的影响也表明，随着本体正极化的增加，扭结减少。
{"title":"Electrical Analysis of Indium Deep Levels Effects on Kink Phenomena of Silicon NMOSFETs","authors":"Abdelaali Fargi, N. Hizem, A. Kalboussi, A. Souifi","doi":"10.4236/WJNSE.2014.41002","DOIUrl":"https://doi.org/10.4236/WJNSE.2014.41002","url":null,"abstract":"Several methods of characterization of trap levels like I-V, C-V and transient spectroscopy (DLTS) were used to determine the accurate values of the activation energies of traps present in N+P junctions obtained after retrograde profile implantation of indium and boron on silicon. Four main traps located at Ev + 0.15 eV, Ev + 0.21 eV, Ev + 0.28 eV and Ev + 0.46 eV are reported. Shallow levels are also calculated from I-V characteristics. Concurrently, indium channel doped NMOSFETs are investigated showing the kink phenomenon. In order to discuss the relationship between the kink effect and the active indium trap level situated at 0.16 eV, the transient effects are studied by varying the integration time and the temperature. The effects of substrate polarization are also carried out showing the reduction of the kink with the bulk positive polarization.","PeriodicalId":66816,"journal":{"name":"纳米科学与工程(英文)","volume":"4 1","pages":"7-15"},"PeriodicalIF":0.0,"publicationDate":"2014-02-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70877923","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2014-02-27DOI: 10.4236/WJNSE.2014.41001
A. Johari, Anoopshi Johari, V. Rana, M. Bhatnagar
In the present work, one-dimensional nanostructures of silicon oxide (SiOx) have been synthesized by thermal annealing method with and without chromium thin film on silicon substrate. The synthesis was carried out at different process temperatures ranging from 1000°C to 1100°C by using gold/chromium (Au/Cr) catalysts stack layer on the Si substrate in nitrogen (N2) ambience. The as-synthesized SiOx nanostructures have tetragonal rutile structure and show polycrystalline nature. The SEM images reveal wire-like nanostructures on the substrate with and without chromium thin film. Under the catalytic reaction of the gold/chromium metal, the density of SiOx nanowires is enhanced, since the Cr layer serves as a diffusion barrier for the diffusion of the gold downwards into the Si substrate. The vapor-liquid solid (VLS) growth mechanism is found to be dominant in the growth of SiOx nanowires. Furthermore, X-Ray diffraction microscopy (XRD) and Photoluminescence spectroscopy (PL) analysis conclude the defect free growth of the SiOx nanowires on gold/chrome/silicon substrate.
{"title":"Role of Chromium Intermediate Thin-Film on the Growth of Silicon Oxide (SiO x ) Nanowires","authors":"A. Johari, Anoopshi Johari, V. Rana, M. Bhatnagar","doi":"10.4236/WJNSE.2014.41001","DOIUrl":"https://doi.org/10.4236/WJNSE.2014.41001","url":null,"abstract":"In the present work, one-dimensional nanostructures of silicon oxide (SiOx) have been synthesized by thermal annealing method with and without chromium thin film on silicon substrate. The synthesis was carried out at different process temperatures ranging from 1000°C to 1100°C by using gold/chromium (Au/Cr) catalysts stack layer on the Si substrate in nitrogen (N2) ambience. The as-synthesized SiOx nanostructures have tetragonal rutile structure and show polycrystalline nature. The SEM images reveal wire-like nanostructures on the substrate with and without chromium thin film. Under the catalytic reaction of the gold/chromium metal, the density of SiOx nanowires is enhanced, since the Cr layer serves as a diffusion barrier for the diffusion of the gold downwards into the Si substrate. The vapor-liquid solid (VLS) growth mechanism is found to be dominant in the growth of SiOx nanowires. Furthermore, X-Ray diffraction microscopy (XRD) and Photoluminescence spectroscopy (PL) analysis conclude the defect free growth of the SiOx nanowires on gold/chrome/silicon substrate.","PeriodicalId":66816,"journal":{"name":"纳米科学与工程(英文)","volume":"04 1","pages":"1-6"},"PeriodicalIF":0.0,"publicationDate":"2014-02-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70877704","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2013-12-05DOI: 10.4236/WJNSE.2013.34019
M. T. Angaji, A. Zinali, N. Qazvini
The present study was carried out on the effect of acid leaching on the modification and structure alteration of montmorillonite. A nanostructured, activated material was prepared by selective leaching of pure smectite clay with different concentrations of sulfuric acid (1 - 10 N/L) at 85°C for 120 min using a solid/liquid ratio of 1:20 and a reflux system. The Fourier transform infrared (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-Ray diffraction (XRD) techniques were used for the characterization and study of the acid-treated montmorillonite clay. Chemical structure of specimens was distinguished by FTIR. The results showed that the formation of Si-OH bonds and leaching of Al3+ ions increased progressively with severity of the acid treatment. As the FTIR studies indicated, acid treatment led to the removal of the octahedral Al3+ cations and an increase in the Si-OH bonds. The morphological alteration of the untreated and treated montmorillonite was investigated by using TEM and SEM. X-ray fluorescence (XRF) analysis revealed a considerable decrease in the relative content of Al by increasing the acid strength. Moreover, the XRD results showed that the treatment using highly concentrated acid resulted in the formation of an amorphous silica phase.
{"title":"Study of Physical, Chemical and Morphological Alterations of Smectite Clay upon Activation and Functionalization via the Acid Treatment","authors":"M. T. Angaji, A. Zinali, N. Qazvini","doi":"10.4236/WJNSE.2013.34019","DOIUrl":"https://doi.org/10.4236/WJNSE.2013.34019","url":null,"abstract":"The present study was carried out on the effect of acid leaching on the modification and structure alteration of montmorillonite. A nanostructured, activated material was prepared by selective leaching of pure smectite clay with different concentrations of sulfuric acid (1 - 10 N/L) at 85°C for 120 min using a solid/liquid ratio of 1:20 and a reflux system. The Fourier transform infrared (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-Ray diffraction (XRD) techniques were used for the characterization and study of the acid-treated montmorillonite clay. Chemical structure of specimens was distinguished by FTIR. The results showed that the formation of Si-OH bonds and leaching of Al3+ ions increased progressively with severity of the acid treatment. As the FTIR studies indicated, acid treatment led to the removal of the octahedral Al3+ cations and an increase in the Si-OH bonds. The morphological alteration of the untreated and treated montmorillonite was investigated by using TEM and SEM. X-ray fluorescence (XRF) analysis revealed a considerable decrease in the relative content of Al by increasing the acid strength. Moreover, the XRD results showed that the treatment using highly concentrated acid resulted in the formation of an amorphous silica phase.","PeriodicalId":66816,"journal":{"name":"纳米科学与工程(英文)","volume":"3 1","pages":"161-168"},"PeriodicalIF":0.0,"publicationDate":"2013-12-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.4236/WJNSE.2013.34019","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70877649","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2013-12-05DOI: 10.4236/WJNSE.2013.34017
M. Yaldagard, M. Jahanshahi, N. Seghatoleslami
Highly-dispersed platinum and platinum-based catalysts on a conductive support are commonly used as electrode materials in low-temperature fuel cells, particularly the hydrogen PEMFC and the direct methanol PEMFC. The performance and durability/stability of these catalysts strongly depend on the characteristics of the support. Catalysts supported on high surface area carbon black are widely used in low-temperature fuel cells. However, the corrosion of carbon black has been recognized as one of major causes of performance degradation and durability issues of low-temperature fuel cells under high-potential conditions. So the need for alternative supports with outstanding physical and mechanical properties to carry out the successful reaction in catalyst layer and give a longer lifetime for the electrocatalysts is inevitable. The emergence of nanotechnology and development of nanostructure materials in recent years has opened up new avenues of materials development for low-temperature fuel cells. This paper presents the performance with a variety of carbon-based nanostructured materials such as carbon nanotubes (CNT), carbon nanofibers (CNF), carbon aerogels, nanoplates of graphene, etc. So the present paper provides an overview of these nanostructured materials as low-temperature fuel cell catalyst supports. The improved characteristics of the nanostructured supports with respect to commercially used carbon black (Vulcan XC-72) and their effect on the electrochemical activity are highlighted. Additionally, it reviews the literature on the synthesis of nanostructured-supported Pt electrocatalysts for proton exchange membrane (PEM) fuel cell catalyst loading reducing through the improvement of catalyst utilization and activity. The features of each synthetic method were also discussed based on the morphology of the synthesized catalysts.
{"title":"Carbonaceous Nanostructured Support Materials for Low Temperature Fuel Cell Electrocatalysts—A Review","authors":"M. Yaldagard, M. Jahanshahi, N. Seghatoleslami","doi":"10.4236/WJNSE.2013.34017","DOIUrl":"https://doi.org/10.4236/WJNSE.2013.34017","url":null,"abstract":"Highly-dispersed platinum and platinum-based catalysts on a conductive support are commonly used as electrode materials in low-temperature fuel cells, particularly the hydrogen PEMFC and the direct methanol PEMFC. The performance and durability/stability of these catalysts strongly depend on the characteristics of the support. Catalysts supported on high surface area carbon black are widely used in low-temperature fuel cells. However, the corrosion of carbon black has been recognized as one of major causes of performance degradation and durability issues of low-temperature fuel cells under high-potential conditions. So the need for alternative supports with outstanding physical and mechanical properties to carry out the successful reaction in catalyst layer and give a longer lifetime for the electrocatalysts is inevitable. The emergence of nanotechnology and development of nanostructure materials in recent years has opened up new avenues of materials development for low-temperature fuel cells. This paper presents the performance with a variety of carbon-based nanostructured materials such as carbon nanotubes (CNT), carbon nanofibers (CNF), carbon aerogels, nanoplates of graphene, etc. So the present paper provides an overview of these nanostructured materials as low-temperature fuel cell catalyst supports. The improved characteristics of the nanostructured supports with respect to commercially used carbon black (Vulcan XC-72) and their effect on the electrochemical activity are highlighted. Additionally, it reviews the literature on the synthesis of nanostructured-supported Pt electrocatalysts for proton exchange membrane (PEM) fuel cell catalyst loading reducing through the improvement of catalyst utilization and activity. The features of each synthetic method were also discussed based on the morphology of the synthesized catalysts.","PeriodicalId":66816,"journal":{"name":"纳米科学与工程(英文)","volume":"3 1","pages":"121-153"},"PeriodicalIF":0.0,"publicationDate":"2013-12-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70877973","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2013-12-05DOI: 10.4236/WJNSE.2013.34016
Khayankhyarvaa Sarangerel, B. Delgertsetseg, N. Javkhlantugs, M. Sakomura, Chimed Ganzorig
The possibility of the increase in open-circuit voltage of organic photovoltaic cells based primarily indium-tin oxide (ITO)/rubrene/fullerene/Al structure by changing the work function of ITO anodes and Al cathodes was described in this work. To change built-in potential preferably in order to increase the open-circuit voltage, the work function of ITO should be increased and work function of Al should be decreased. The correlation between the change in work functions of electrodes and performance of the organic photovoltaic cells before and after surface modifications was examined in detail. The enhancement of open-circuit voltage depends on a function of work function change of both ITO and Al electrode. We could show that the built-in potential in the cells played an important role in open-circuit voltage.
{"title":"Improvement of Open-Circuit Voltage in Organic Photovoltaic Cells with Chemically Modified Indium-Tin Oxide","authors":"Khayankhyarvaa Sarangerel, B. Delgertsetseg, N. Javkhlantugs, M. Sakomura, Chimed Ganzorig","doi":"10.4236/WJNSE.2013.34016","DOIUrl":"https://doi.org/10.4236/WJNSE.2013.34016","url":null,"abstract":"The possibility of the increase in open-circuit voltage of organic photovoltaic cells based primarily indium-tin oxide (ITO)/rubrene/fullerene/Al structure by changing the work function of ITO anodes and Al cathodes was described in this work. To change built-in potential preferably in order to increase the open-circuit voltage, the work function of ITO should be increased and work function of Al should be decreased. The correlation between the change in work functions of electrodes and performance of the organic photovoltaic cells before and after surface modifications was examined in detail. The enhancement of open-circuit voltage depends on a function of work function change of both ITO and Al electrode. We could show that the built-in potential in the cells played an important role in open-circuit voltage.","PeriodicalId":66816,"journal":{"name":"纳米科学与工程(英文)","volume":"3 1","pages":"113-120"},"PeriodicalIF":0.0,"publicationDate":"2013-12-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.4236/WJNSE.2013.34016","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70877899","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2013-12-05DOI: 10.4236/WJNSE.2013.34018
Y. Shaban
Photocatalytic reduction of toxic Cr(VI) was successfully achieved using carbon modified titanium oxide (CM-n-TiO2) nanoparticles under natural sunlight illumination. Modification of titanium oxide by carbon significantly enhanced the photocatalytic reduction of Cr(VI) under natural sunlight irradiation. The effects of various experimental parameters such as catalyst dose, initial concentration of Cr(VI), and solution pH on the reduction rate of Cr(VI) were investigated. The highest reduction rate of Cr(VI) was obtained at the optimal conditions of pH 5 and 2.0 g·L?1 of CM-n-TiO2. Interestingly, in the presence of phenol, as a sacrificial electron donor, the rate of Cr(VI) reduction was nearly 1.7 times higher than in its absence. The solar photoreduction of Cr(VI) in aqueous solution using CM-n-TiO2 obeyed a pseudo-first order kinetics according to the Langmuir-Hinshelwood model.
{"title":"Effective Photocatalytic Reduction of Cr(VI) by Carbon Modified (CM)-n-TiO2 Nanoparticles under Solar Irradiation","authors":"Y. Shaban","doi":"10.4236/WJNSE.2013.34018","DOIUrl":"https://doi.org/10.4236/WJNSE.2013.34018","url":null,"abstract":"Photocatalytic reduction of toxic Cr(VI) was successfully achieved using carbon modified titanium oxide (CM-n-TiO2) nanoparticles under natural sunlight illumination. Modification of titanium oxide by carbon significantly enhanced the photocatalytic reduction of Cr(VI) under natural sunlight irradiation. The effects of various experimental parameters such as catalyst dose, initial concentration of Cr(VI), and solution pH on the reduction rate of Cr(VI) were investigated. The highest reduction rate of Cr(VI) was obtained at the optimal conditions of pH 5 and 2.0 g·L?1 of CM-n-TiO2. Interestingly, in the presence of phenol, as a sacrificial electron donor, the rate of Cr(VI) reduction was nearly 1.7 times higher than in its absence. The solar photoreduction of Cr(VI) in aqueous solution using CM-n-TiO2 obeyed a pseudo-first order kinetics according to the Langmuir-Hinshelwood model.","PeriodicalId":66816,"journal":{"name":"纳米科学与工程(英文)","volume":"2013 1","pages":"154-160"},"PeriodicalIF":0.0,"publicationDate":"2013-12-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70877596","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2013-09-06DOI: 10.4236/WJNSE.2013.33007
Tegshjargal Khishigjargal, N. Javkhlantugs, Chimed Ganzorig, Youji Kurihara, M. Sakomura, K. Ueda
The properties of the modified surface of SnO2(110) with benzoic acid (Y-C6H4-COOH: Y is para position relative to -COOH group) derivatives were investigated using density functional theory. Zehner et al. mentioned that the modification of surface dipole moment made it possible to tune the work function of the system. The experiment of Ganzorig et al. showed that there was a linear relationship between the dipole moment of the binding molecule and the work function change of the system using the modified surface of indium-tin oxide (ITO) with some benzoic acid derivatives. To elucidate the relation between the dipole moment of the molecule and the work function change, we investigated the modified surface of SnO2(110) using Sn7O14 cluster model which was embedded in the fixed point charges. On the modification of the surface, benzoic acid derivatives were bound to SnO2 surface. By changing the terminal group of benzoic acid with H, Cl, F, CF3 and CCl3, the work function changed and the dipole moment of the binding molecules of the modified SnO2(110) were evaluated. The results showed that there was a linear relationship between the dipole moment of the binding molecules and the work function changed. From this relation, the average value of the dipole moments of Sn-OOC linkage at the surface was also evaluated.
{"title":"Density Functional Study of the Cluster Model of SnO 2 (110) Surface Modified by Benzoic Acids","authors":"Tegshjargal Khishigjargal, N. Javkhlantugs, Chimed Ganzorig, Youji Kurihara, M. Sakomura, K. Ueda","doi":"10.4236/WJNSE.2013.33007","DOIUrl":"https://doi.org/10.4236/WJNSE.2013.33007","url":null,"abstract":"The properties of the modified surface of SnO2(110) with benzoic acid (Y-C6H4-COOH: Y is para position relative to -COOH group) derivatives were investigated using density functional theory. Zehner et al. mentioned that the modification of surface dipole moment made it possible to tune the work function of the system. The experiment of Ganzorig et al. showed that there was a linear relationship between the dipole moment of the binding molecule and the work function change of the system using the modified surface of indium-tin oxide (ITO) with some benzoic acid derivatives. To elucidate the relation between the dipole moment of the molecule and the work function change, we investigated the modified surface of SnO2(110) using Sn7O14 cluster model which was embedded in the fixed point charges. On the modification of the surface, benzoic acid derivatives were bound to SnO2 surface. By changing the terminal group of benzoic acid with H, Cl, F, CF3 and CCl3, the work function changed and the dipole moment of the binding molecules of the modified SnO2(110) were evaluated. The results showed that there was a linear relationship between the dipole moment of the binding molecules and the work function changed. From this relation, the average value of the dipole moments of Sn-OOC linkage at the surface was also evaluated.","PeriodicalId":66816,"journal":{"name":"纳米科学与工程(英文)","volume":"3 1","pages":"52-56"},"PeriodicalIF":0.0,"publicationDate":"2013-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70877515","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2013-09-06DOI: 10.4236/WJNSE.2013.33014
M. Ghasemifard, Meisam Daneshvar, M. Ghamari
By using nitric acid as the fuel, the lead-free ceramic of Ba(Ti1-x,Mgx)O3 (x = 0.31) was prepared by auto combustion method (ACM). To make a comparison, this ceramic was also prepared using mixed oxide method (MOM). By X-ray diffraction, the phase structures of two samples were studied, and the results showed that rising temperatures would reduce unwanted phases. The piezoelectric and electrical properties as a function of calcination and sintering temperatures were investigated. The results showed that the outstanding electrical properties were obtained for nanoceramic with this composition. The SEM image of the grain size was estimated around 2 micrometers, and the grain size increased with the increasing of sintering temperature for two samples. The curie temperature of the BMT-ACM was 126°C and it’s significantly larger than the curie temperature of BMT-MOM which was 118°C. The results of electrical properties emphasized that the synthesis optimum temperature for two samples was about 1200°C and it was the best temperature that led to improved properties such as dielectric constant, polarization and piezoelectric coefficients.
{"title":"The Effects of Annealing Process on Dielectric and Piezoelectric Properties of BMT-Base Lead-Free Ceramics","authors":"M. Ghasemifard, Meisam Daneshvar, M. Ghamari","doi":"10.4236/WJNSE.2013.33014","DOIUrl":"https://doi.org/10.4236/WJNSE.2013.33014","url":null,"abstract":"By using nitric acid as the fuel, the lead-free ceramic of Ba(Ti1-x,Mgx)O3 (x = 0.31) was prepared by auto combustion method (ACM). To make a comparison, this ceramic was also prepared using mixed oxide method (MOM). By X-ray diffraction, the phase structures of two samples were studied, and the results showed that rising temperatures would reduce unwanted phases. The piezoelectric and electrical properties as a function of calcination and sintering temperatures were investigated. The results showed that the outstanding electrical properties were obtained for nanoceramic with this composition. The SEM image of the grain size was estimated around 2 micrometers, and the grain size increased with the increasing of sintering temperature for two samples. The curie temperature of the BMT-ACM was 126°C and it’s significantly larger than the curie temperature of BMT-MOM which was 118°C. The results of electrical properties emphasized that the synthesis optimum temperature for two samples was about 1200°C and it was the best temperature that led to improved properties such as dielectric constant, polarization and piezoelectric coefficients.","PeriodicalId":66816,"journal":{"name":"纳米科学与工程(英文)","volume":"03 1","pages":"100-107"},"PeriodicalIF":0.0,"publicationDate":"2013-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70877781","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2013-09-06DOI: 10.4236/WJNSE.2013.33010
R. Kozakevych, Y. Bolbukh, V. Tertykh
The release profiles of acidic form of diclofenac sodium adsorbed on mesoporous silicas (Silochrom and two samples of spherical silicas) were compared with the dissolution characteristics of the pure drug. Desorption of diclofenac sodium from impregnated silicas with various surface liophilicity and composites of silica with chitosan have been studied using rotating basket method in phosphate buffer, pH 6.8. Sedimentations of sodium diclofenac via adsorption and impregnation from alcohol solution on fumed silica and modified silicas with grafted aminopropyl and trimethylsilyl groups were carried out. Polymer-containing composites have been prepared by capsulation of silica particles with impregnated diclofenac sodium by protonated and deprotonated forms of chitosan. Effect of the silica surface nature on the active substance release rate was ascertained. Significant prolongation of diclofenac sodium release was detected in the case of application of hydrophobic silica as a carrier and protonated chitosan as a polymeric shell.
{"title":"Controlled Release of Diclofenac Sodium from Silica-Chitosan Composites","authors":"R. Kozakevych, Y. Bolbukh, V. Tertykh","doi":"10.4236/WJNSE.2013.33010","DOIUrl":"https://doi.org/10.4236/WJNSE.2013.33010","url":null,"abstract":"The release profiles of acidic form of diclofenac sodium adsorbed on mesoporous silicas (Silochrom and two samples of spherical silicas) were compared with the dissolution characteristics of the pure drug. Desorption of diclofenac sodium from impregnated silicas with various surface liophilicity and composites of silica with chitosan have been studied using rotating basket method in phosphate buffer, pH 6.8. Sedimentations of sodium diclofenac via adsorption and impregnation from alcohol solution on fumed silica and modified silicas with grafted aminopropyl and trimethylsilyl groups were carried out. Polymer-containing composites have been prepared by capsulation of silica particles with impregnated diclofenac sodium by protonated and deprotonated forms of chitosan. Effect of the silica surface nature on the active substance release rate was ascertained. Significant prolongation of diclofenac sodium release was detected in the case of application of hydrophobic silica as a carrier and protonated chitosan as a polymeric shell.","PeriodicalId":66816,"journal":{"name":"纳米科学与工程(英文)","volume":"03 1","pages":"69-78"},"PeriodicalIF":0.0,"publicationDate":"2013-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70877137","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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