جستجوی مقالات مرتبط با کلیدواژه "structural properties" در نشریات گروه "شیمی"
تکرار جستجوی کلیدواژه «structural properties» در نشریات گروه «علوم پایه»-
The fabrication of two composites using polymers (A) and (B) reinforced with nano-Alumina in ratios of (8,4)%, respectively, was the main focus of this study. To study the effect of both the irradiation time and the effectiveness of the radioactive sources, the manufactured samples were exposed to different periods (1,2,3) days when irradiated with sources of different efficacy (Sr90), (Co60). From the results of the examination via the atomic force microscope, it was found that the rate of distribution of the granular sizes and the nature of the surface of composite B was affected when the irradiation time was increased, as well as when using different sources of effectiveness, while composite A was very weakly affected by these conditions. It was also noted that the mechanical properties were affected by the irradiation parameters, where we notice a decrease in the hardness values and an improvement in the impact strength of both compounds when the source efficiency increases and the irradiation duration increases. The infrared spectrum gave a great role in the irradiation time, and it affected the appearance and disappearance of beams when irradiated with different sources on the two complexes. In the case of composite A, the CH band disappeared on the first day of irradiation with a source (Co60). The rest of the bands appeared, but with varying intensity and frequency, with a slight displacement when the irradiation source changed. It was also noticed that there was a disappearance of the same beam for the composite (B) but on the third day of exposure to the (Sr90) source. This disappearance or displacement of the beams indicates a kind of disintegration in the polymer chains. Increasing the percentage of nanopowder addition to the composite improves the mechanical.Keywords: Mechanical Properties, Nanoparticles Of Alumina, Polymeric Composite, Structural Properties
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This study used sol-gel and hydrothermal methods to prepare binary bioactive glasses (BG) of SiO2-CaO with 63% and 37% molar fractions, respectively. Different techniques characterized heat-treated powders: Thermogravimetric analysis (TGA), Fourier-transformed infrared spectroscopy (FTIR), X-ray diffraction (XRD) analysis, inductively coupled plasma-atomic emission analysis (ICP-AES), solid-state nuclear magnetic resonance (NMR), scanning electron microscopy and energy dispersive spectroscopy (SEM-EDS), and Brunauer-Emmett-Teller analysis (BET). According to both synthetic routes, the HT technique presented better new apatite layers deposition on BG particles during in vitro bioactivity assessment in simulated body fluid (SBF). The bioactivity is confirmed by XRD analysis, NMR spectroscopy, and BET analysis showing that HT-derived bioactive glass (BG-HT) presents higher bioactivity than sol-gel-derived BG (BG-SG), and the nanometric particle size of HT-BG (90-100 nm) with a high specific surface area is responsible for this enhancement. Furthermore, NMR spectroscopy indicates the higher network connectivity of HT-derived bioactive glass due to different environments in this structure. Moreover, SEM-EDS micrographs of BG-HT glasses show spherical nanoparticles, while BG-SG results present a mixture of spherical and rod-like microparticles. The HT-BG could be a promising material for biomedical applications, especially in drug delivery and ion release.Keywords: Structural properties, bioglass, Solid-state NMR, Sol-Gel, Hydrothermal, Bioactivity
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در این پژوهش، مطالعات ساختاری و خواص ترمولومینسانس و فوتولومینسانس نانوذرات CaZrO3 جانشانی شده با Ce3+ در غلظت های مختلف (mol% 0/6-0/1=x) بررسی شد. مطالعه ساختاری نمونه ها با طیف سنج پراش پرتو ایکس (XRD) و میکروسکوپ الکترونی روبشی -گسیل میدانی (FE-SEM) انجام شد. الگوی XRD دلالت بر تشکیل ساختار پروسکایت در دمای °C700 داشت. خواص ترمولومینسانس نانوفسفرهای +CaZrO3:xCe3 در دمای اتاق تحت پرتودهی پرتو ایکس در زمان های مختلف بررسی شد. بیشینه شدت ترمولومینسانس برای نمونه CaZrO3:xCe+3 با ناخالصی mol%0/2=x به دست آمد. نمونه Ca0.998Ce0.002ZrO3 در بازه های زمانی 1 تا min 15 تحت پرتودهی پرتو ایکس قرار گرفت. با افزایش زمان پرتودهی، تعداد حامل های بار افزایش می یابد که افزایش شدت ترمولومینسانس را نتیجه می دهد. خطی بودن، تکرارپذیری و محوشدگی نیز برای این نمونه بررسی شد که با توجه به پایداری قابل توجه، محوشدگی پایین و خطی بودن پاسخ ترمولومینسانس، می تواند گزینه مناسبی برای دزیمتری باشد. مطالعه رفتار فوتولومینسانس در دمای اتاق نشان داد هنگامی که نانوفسفرها با نور با طول موج nm 253 برانگیخته می شوند، به ترتیب سه قله انتشار در 404، 425 و nm 488 مشاهده می شود. با افزایش غلظت یون Ce3+، قله های انتشار در طیف فوتولومینسانس از ناحیه بنفش به آبی جابه جا می شود.
کلید واژگان: خواص ساختاری, لومینسانس, نانوفسفر, Ca1-xZrO3:xCe+3, پرتو ایکسIn this study, structural studies, photoluminescence and thermoluminssence properties of CaZrO3 nanoparticles added with Ce3+ ion at different concentrations (x = 0.1-0.6 mol%) were investigated. Structural analysis of the samples was performed by X-ray diffraction (XRD) and field emission scanning electron microscopy (FE-SEM). The XRD pattern indicated the formation of a perovskite structure at 700 °C. The thermoluminssence (TL) properties of CaZrO3:xCe3+ nanophosphors were investigated at room temperature under X-ray at different times. Maximum TL intensity was obtained for Ca0.998Ce0.002ZrO3 samples. The sample of Ca0.998Ce0.002ZrO3 was exposed to X-ray at different time intervals from one to 15 minutes. As the irradiation time increases, the number of charge carrier increases, which results in an increase in the intensity of TL. Linearity, reproducibility and fading were also investigated for this sample, which is suitable for TL dosimetry due to its significant stability, low fading and linearity of the TL response. Study of photoluminescence (PL) behavior at room temperature showed when the phosphors were excited by light with a wavelength of 253 nm, three emission peaks at 404, 425 and 488 nm were obtained, respectively. By increasing Ce concentration, the emission peaks in PL spectra slightly shift from violet region to blue region.
Keywords: structural properties, luminescent, nanophosphors, Ca1-xZrO3:xCe3+, X-ray -
In this research, The effect of substrate temperature was studied at different temperatures 250, 350 and 450 ⁰C. Structural properties of the films were determined using X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM). The X-ray diffraction results showed that all the prepared films were polycrystalline, orthorhombic in structure, and a preferred orientation (301),(602) and (111) . The crystallinity of the thin film (SnS) increases with the increase in the temperature (substrate). The electrical properties showed all thin films p-type and D.C conductivity measurements showed that the conductivity increased with increasing temperatures and I-V characteristics were also studied under dark.Keywords: Chemical spray technique, Electrical properties, I-V characteristics, Structural properties, Tin Sulfide
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In this work, pure copper oxide and Fe-doped copper oxide nanostructures [Cu1-x FexO where 0 ≤ x ≤ 0.08 in steps of 0.02] were synthesized using the co-precipitation method. Iron nitrate nano-hydrate and copper nitrate trihydrate were used as precursors and NaOH was used as precipitating agent. The samples were investigated by X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Energy-Dispersive X-ray Spectroscopy (EDS), and UV-Visible spectroscopy for their structural, morphological, and optical properties, respectively. The effect of iron concentration on antibacterial activity and hemolysis was also investigated for Escherichia coli and Bacillus Subtilis. The XRD pattern showed a single-phase monoclinic structure of CuO nanoparticles. The average crystallite size of pure copper oxide was found 39 nm whereas the average crystallite size of Fe-doped CuO was found in the range 39-44 nm. It was observed that average crystallite size was increased with an increasing iron concentration in CuO. Scanning electron microscopy analysis showed spherical-like morphology and EDS confirmed the presence of iron and copper with proper composition. UV-vis spectroscopy results showed that the band gap was decreased with increasing iron concentration. Samples prepared with higher concentrations of iron exhibited high E. coli and B. subtilis antibacterial activity. Low hemolytic is safer to be used in various applications such as drug delivery.Keywords: Fe-doped CuO, co-precipitation, structural properties, Antibacterial activity, hemolysis, Toxicity
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International Journal Of Nanoscience and Nanotechnology, Volume:18 Issue: 3, Summer 2022, PP 187 -195This work synthesized NiO nanoparticles by chemical precipitation and thermal decomposition methods at different annealing temperatures. The properties of synthesized nanopowders were compared by X-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier transformed infrared (FT-IR). The X-ray diffraction pattern analysis indicated that samples annealed at 300℃ and 600℃ have face-centered cubic (fcc) with lattice parameter a= 4.17960 and hexagonal structures with lattice parameters a=b= 2.95 , c=7.23 , respectively. Also, by increasing annealing temperature, the crystallinity and size of NiO nanoparticles have increased, and samples synthesized by the chemical precipitation method have a smaller size than other samples. For 600℃ calcination temperature and compared to other methods, XRD pattern of samples synthesized by thermal decomposition method showed higher intensity of peaks which resulted in larger nanoparticles. FT-IR results confirmed the formation of NiO nanoparticle composition. Also, the FT-IR spectrum of samples synthesized with different methods and varying annealing temperatures didn't change significantly. This enhanced chemical understanding is paramount for the rational control of synthesizing NiO and its applications in electronic and electro-optical research.Keywords: Nickel oxide, Nanoparticle, structural properties, Chemical precipitation, Thermal decomposition
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در پژوهش حاضر، به بررسی ویژگی ساختاری و الکترونی نانولایه دی اکسید قلع بااستفاده از بسته ی محاسباتی کوانتوم اسپرسو بر مبنای نظریه ی تابعی چگالی، به کمک رهیافت شبه پتانسیل فوق نرم و تقریب گرادیان تعمیم یافته، پرداخته ایم. ساختار خالص این مدل از دی اکسید قلع نیم رساناست. هدف از این پژوهش، بررسی اثر ناخالصی هایی مانند مس،انتیموان، تیتانیم، پلاتین وآهن (دربخش مغناطیسی) بر خواص ذکر شده ی نانولایه دی اکسید قلع است. بررسی طول پیوندها، ساختار نواری و چگالی حالات نشان می دهند که افزودن ناخالصی های پلاتین، آنتیموان، تیتانیم و مس باعث بهبودرسانندگی نانولایه دی اکسید قلع می شود؛ افزودن آهن همچنین، باعث ایجاد خاصیت مغناطیسی در آن می شود.
کلید واژگان: نانولایه دی اکسید قلع, اثر ناخالصی, خواص الکترونی و ساختاریNano scale, Volume:9 Issue: 2, 2022, PP 163 -170In the present research, the structural and electronic properties of SnO2 nanolayer have been investigated using Quantum ESPRESSO integrated suite based on density-functional theory using ultrasoft pseudopotential approach and the generalized-gradient approximation. The pure structure of this slab model of SnO2 is semiconductor. The aim of this research is to investigate the effect of the impurities Pt, Sb, Ti, Cu, and Fe (in the magnetic part) on the aforementioned properties of SnO2 nanolayer. Examining the related bond lengths, band structures and density of states indicate that adding Pt, Sb, Ti, and Cu impurities enhances the conductivity of SnO2 nanolayer; adding Fe impurity also induces magnetic properties to the nanolayer.
Keywords: Tin dioxide nanolayer, Effect of impurity, Electronic, structural properties -
در این مطالعه، با محاسبه ی ویژگی ساختاری، الکترونی، نوری و فتوکاتالیستی تک لایه های مکسین، یک خانواده از مواد دو بعدی با کاربردهای گسترده ی آن ها به دلیل ویژگی برجسته شان، از جمله Hf2CO2 و Zr2CO2 ، این تک لایه ها را با استفاده از تابعی های GGA-PBE و HSE06 مورد مقایسه قرار می دهیم. این محاسبات با استفاده از نظریه ی تابعی چگالی (DFT) انجام شده است. سلول واحد این ساختارها و موقعیت اتمی آن ها کامل بهینه شده است. نتایج نشان می دهد که ثابت های شبکه برای نانوساختارهای دو بعدی Hf2CO2 و Zr2CO2 به ترتیب 3/3592 و 3/3771 آنگستروم است. گاف نواری این نانوساختارها از نوع غیرمستقیم است. بر اساس اطلاعات بدست آمده مقدار گاف نواری آن ها با تابعی GGA-PBE به ترتیب 0/92 و0/89 الکترون ولت است. همچنین با تابعی هیبریدی HSE06، گاف نواری بدست آمده به ترتیب 1/75 و 1/72 الکترون ولت است. مشاهده می شود که با تابعی هیبریدی HSE06، میزان گاف نواری بهبود می یابد. بخش های حقیقی و موهومی تابع دی الکتریک به منظور بررسی ویژگی نوری این ساختارها محاسبه شده است. محاسبات نشان می دهند که مواد مورد مطالعه در مناطق مریی و فرابنفش از جذب بالایی برخوردار هستند. نتایج بدست آمده نشان می دهد که این نانوساختارهای دو بعدی می توانند به عنوان فتوکاتالیست مناسب در فرایند شکافت آب مورد استفاده قرار گیرند.کلید واژگان: خواص ساختاری, خواص الکترونی, خواص اپتیکی, فتوکاتالیست, نظریه ی تابعی چگالی (DFT), نانوساختارهای دو بعدیNano scale, Volume:9 Issue: 2, 2022, PP 92 -107In this paper, the structural, electronic, optical, and photocatalytic properties of MXene monolayers are studied. MXenes are a new class of two-dimensional (2D) transition metal carbides and nitrides with the chemical formula Mn+1Xn (M = Sc, Ti, V, Cr, Zr, Nb, Mo, Hf, Ta; X = C, N; n = 1–3) that etching MAX phases have recently synthesized. We study Hf2CO2 and Zr2CO2 nanostructures, comparing them with the GGA-PBE and HSE06 functionals. These calculations were performed using density functional theory (DFT). The unit cell of these structures and their atomic positions are fully optimized. The results show that the lattice constants for two-dimensional nanostructures Hf2CO2 and Zr2CO2 are 3.3592 and 3.3771 angstroms, respectively. The band gap of these nanostructures is of the indirect type. Based on the information obtained, their band gap values with GGA-PBE functional are 0.92 and 0.89 eV, respectively. The results of calculations with HSE06 hybrid functional show that both Hf2CO2 and Zr2CO2 nanostructures are semiconductors with band gaps of 1.75 and 1.72 eV. It can be seen that with an HSE06 hybrid functional, the amount of band gap improves. The real and imaginary parts of the dielectric function have been calculated to investigate the optical properties of these structures. In addition, the studied materials have high absorption in visible and ultraviolet regions. The obtained results show that these nanostructures may apply in designing optoelectronic devices.Keywords: structural properties, Electronic properties, Optical Properties, photocatalyst, Density Functional Theory (DFT), Two-Dimensional Nanostructures
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Hierarchical Cadmium Sulphide (CdS) thin films with high-surface area were deposited on a glass substrate using a hydrothermal technique at various deposition periods' durations for the first time. As-deposited CdS films have been investigated structural, optical, morphological, and photocatalytic properties. The results demonstrate that the deposition period has a substantial impact on the physical and chemical characteristics of these films. X-ray diffraction (XRD) revealed that the structural characteristics of all samples are hexagonal and cubic phases. Field emission scanning electron microscopy (FE-SEM) reveals the development of hierarchical nanoflowers with tiny gaps at lower deposition times; nevertheless, the density of the nanoflakes rises as the deposition time increases. Atomic force microscope (AFM) images of the films indicate morphological alterations and an increase in surface roughness from 4.58 nm to 7.26 nm. In conjunction with different time deposition, the photoluminescence (PL) behavior of the samples is outstanding, with acceptable transmittance spectra in the visible range. The optical band gap is directly connected to the deposition conditions, according to the transmittance data analysis; a direct bandgap ranging from 2.34 to 2.17 e V was calculated. The nanoflowers cadmium sulfide films exhibited unprecedented photocatalytic activities for the decomposition of methyl blue (MB) and methyl violet (MV) dyes, because high surface area, low energy gap, and efficient charge separation properties for prepared films.Keywords: CdS Thin Films, Deposition time, Hydrothermal method, Optical properties, Photocatalytic properties, Structural properties
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In this study, single-phase bismuth ferrite (BiFeO3) was synthesized using hydrothermal method. The effect of KOH concentration and temperature during the reaction on morphology, particle size, and phase formation was investigated. Then, the structural properties of the samples were assessed using X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), Fourier transform-infrared spectroscopy (FT-IR), and vibrating sample magnetometer (VSM) analysis. XRD analysis results revealed that the samples were fabricated in distorted rhombohedral perovskite structure with R3C space group. Also, BiFeO3 (BFO) was formed in a single-phase at 220 °C and 4M concentration of KOH. The magnetic properties of the optimal sample were determined by VSM analysis and very weak magnetic properties were observed in pure nanoparticles. Also, the optical properties and photocatalytic properties of the optimal sample were investigated by UV-visible and Photoluminescence (PL) analysis. The optical gap of BFO was recorded by 2.8 and its photocatalytic properties were investigated at three different pHs (2, 6, and 10) at a concentration of 20 ppm Congo red. The results demonstrated that BFO nanoparticles nearly destroyed dye structure after 120 min at pH = 2.Keywords: Bismuth ferrite, Hydrothermal method, Structural properties, Magnetic properties, photocatalytic properties
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International Journal Of Nanoscience and Nanotechnology, Volume:17 Issue: 2, Spring 2021, PP 107 -119The present research work focused on the synthesis, characterization and testing of antimicrobial activity of CuO nanoparticles prepared by green synthesis method usingTrigonella foenum-graecum L. leaf extract. The XRD pattern indicated the presence of cubic structure of nanocrystalline CuO with crystallite size of 47 nm. The optical band gap was calculated using Tauc’s plot and found to be 3.6 eV. SEM images revealed that the particles had cluster structures with a combination of different shapes. EDAX analysis confirmed the presence of copper and oxide by indicating predominant peak which was the highest percentage present in the spectrum. The synthesized nanoparticles showed significant antibacterial and antifungal activity against the human pathogens Staphylococcus aureus and Penicillium sp. So this nanoparticle can be considered as an alternate approach for reducing the adhesion ofmicro-organisms.Keywords: CuO, Green synthesis, structural properties, morphological, Antimicrobial activity.
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In this study, the doping impact of indium (In) on the actual properties of CdO at different content of (1, 2, and 3 wt% In) was discussed. The samples were prepared utilizing the spray pyrolysis method. The structural, topographical, and optical properties were characterized X-ray diffraction (XRD) analysis, UV-Vis, and atomic force microscope (AFM). The surface topography was discussed by utilizing AFM analysis. Results display that the average diameter appears to be dependent on the indium content. The particle size was decreased from 78.05 to 65.77 nm when In content was increased from 0% to 3%. It is found that the roughness of the film was decreased to 3.03 nm via increasing In content to 3%. Also, the band gap of prepared samples were studied and compared. Results revealed that the value of band gap is decreasing via doping indium. The band gap of bare CdO, 1%In-CdO, and 3%In-CdO were determined 2.63, 2.54, and 2.46 respectively.Keywords: CdO thin film, Indium doping, Optical properties, Structural properties
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Tin oxide (SnO2)nanoparticles were synthesized by co-precipitation method and the synthesized nanoparticles were annealed at different temperatures for characterization. The powders were investigated with X-ray diffraction, scanning electron microscopy and optical spectroscopy. The structural characterization was carried out by X-ray diffraction which confirms the crystalline nature of the films with a tetragonal structure. SEM analysis of the powders enabled the conclusion that the prepared nanoparticles are spherical particles which are smaller in size composed of clustered and agglomerated nanoparticles. From the absorption spectra the type of transition and band gap of the synthesized nanoparticles were estimated. The optical (UV-visible) spectrum exhibits a well defined absorption which in considerably blue shifted related to the peak absorption of bulk SnO2 indicating quantum size effect.Keywords: Morphological properties, optical properties, Quantum Size Effect, SEM, Structural Properties, Tetragonal Structure, Tin Oxide Nanoparticles
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در این مطالعه ویژگی های ساختاری از جمله ثابت های شبکه، مدول حجمی و الکترونی ترکیب های (X=S,Se,Te) AgGaX2 وCuSbX2 (X=S,Se,Te) در حالت انبوه در چارچوب نظریه تابعی چگالی و روش موج های تخت بهبود یافته خطی با پتانسیل کامل (FP-LAPW) با استفاده از نرم افزار Wien2k محاسبه شده است. هم چنین برای بررسی ویژگی های الکترونی این ترکیب ها، چگالی حالت های کل، ساختار نواری، چگالی حالت های جزیی و چگالی ابر الکترونی رسم شده اند. نتیجه های به دست آمده نشان می دهد که هر سه ترکیب نیم رسانا دارای گاف مستقیم در نقطه Γ می باشد. با توجه به چگالی ابر الکترونی و چگونگی توزیع ابر الکترونی در اطراف اتم ها، نشان م ی دهد که پیوند بین ات م ها در ترکیب های(X=S,Se,Te) AgGaX2 وCuSbX2 (X=S,Se,Te) کووالانسی است. هم چنین با استفاده از منحنی های چگالی حالت ها، چگونگی هم پوشانی اربیتال ها بیان شده اند. از سویی با رسم نمودار ساختار نواری ترکی ب ها با تقریب های گوناگون برای انرژی تبادلی همبستگی، میزان و دقت گاف های نواری ترکیب ها مشخص شده است که نتیج ه های به دست آمده با دیگر نتیجه های تجربی موجود سازگار می باشد.
کلید واژگان: کلکوپریت, کلکوژنید, ویژگی های ساختاری, ویژگی های الکترونی, نظریه تابعی چگالیIn this Research, structural and electronic properties of AgGaX2(X=S, Se, Te) and were studied using full potential linear augmented plane wave (FP-LAPW) within the framework of density functional theory using Wien2k code. The lattice constants, bulk modulus (B), and its first derivative (B') were calculated to investigate the structural properties. Total and partial density of states, band structure, and electron density were plotted to investigate the electronic properties of all materials. All compounds were semiconductors with direct bandgap energy in Γ point and the results are found to agree with the experiment. The orbital overlap was explained by using the partial density of states, also electron density shown that AgGaX2(X=S, Se, Te) and CuSbX2(X=S, Se ,Te) compounds have covalent bonds.
Keywords: chalcopyrite, Chalcogenide, Electronic properties, structural properties, DFT -
در این مقاله نانوذرات دی اکسید تیتانیوم با استفاده از روش سل ژل سنتز شدند. تاثیر زمان ماندگاری سل و همچنین اثر دمای کلسیناسیون بر خواص فیزیکی و ساختاری نانوذرات تهیه شده با استفاده از روش های آنالیز حرارتی TG/DTA، پراش پرتو ایکس XRD، میکروسکوپ الکترونی عبوری TEM و تحلیل آماری توزیع اندازه ذرات، بررسی شدند. آنالیز حرارتی DTA نمونه ساخته شده سه ناحیه کاهش وزنی از خود نشان می دهد. نتایج آنالیز XRD نشان داد که فاز نمونه ها تا دمای 700 درجه آناتاز بود، اما در دمای 800 درجه تغییر فاز نسبی به روتایل مشاهده شد و نانوذرات مخلوطی از فاز آناتاز و روتایل داشتند. نمونه کلسینه شده در دمای 900 درجه دارای فاز خالص روتایل بود. نتایج نشان می دهد که با افزایش دمای بازپخت، اندازه ذرات بزرگتر شده است. همچنین زمان ماندگاری تاثیری بر روی فاز بلوری نمونه ها نداشت. طیف FTIR نمونه ها نشان دهنده تشکیل پیوند Ti-O و O-Ti-O است. پیک های جذبی مربوط به پیوندهای متقارن و نامتقارن CO پس از بازپخت از شدت آن کاسته شده و در دماهای بالاتر از بین رفته است. تصویر TEM نشان دهنده کروی بودن نانوذرات با قطر میانگین nm 2/13 می باشد.
کلید واژگان: نانوذره, سل ژل, دی اکسید تیتانیم, ویژگی ساختاری, گذار فازNano scale, Volume:6 Issue: 4, 2020, PP 102 -109In this paper nanoparticles of titanium dioxide have been synthesized by sol-gel method. Effect of sol aging time as well as calcination temperature on physical and structural properties of the nanoparticles have been studied by thermal analysis TG/DTA, x-ray diffraction XRD, transmission electron microscope TEM, and statistical analysis of particle size distribution. DTA thermal analysis of the sample shows three weight-loss regions. XRD analysis shows that samples have anatase phase up to 700 ºC, but at 800 ºC relative phase change to rutile can be seen and nanoparticles have mixed anatase and rutile phases. The samples calcined at 900 ºC have pure rutile phase. The results show that by increasing the calcination temperature the size of nanoparticles has increased and the largest crystallite size for anatase phase is obtained 38.7 nm and 147.5 nm for rutile phase. Furthermore, aging time has no effect on the crystalline phase of samples. FTIR spectra of the samples indicate the formation of Ti-O and O-Ti-O bonds. Absorption peaks which are related to symmetric and asymmetric CO bonds have been reduced after calcination and have been lost at higher temperatures. TEM image confirms the nanoparticles are spherical with 13.2 nm average diameter.
Keywords: nanoparticle, sol-gel, titanium dioxide, structural properties, phase transition -
During recent years, the silicon organic-inorganic compounds play the key role in medicinal chemistry and pharmaceutical industry. This is because of their similar chemical properties with carbon compounds. The second reason is related to their easy transfer from the cell membranes. So, molecular simulation and study the properties of novel organosilicon compounds can be more important. From this sight of view, we designed and investigated silicon analogs of benzene ring before. Here, the various derivatives of hexasiline molecule will be discussed in the following. Our investigations are based on the density functional theory (DFT) computations. The present research work was focused on investigation of the structural and spectral properties and reactivity of hexasiline using B3LYP/cc-pVDZ level of theory. The Fukui indices (local reactivity) showed that the electrophilic attacks happen on the Si4 atoms of the molecules. On the other hand, the molecules containing electron-donating and electron-withdrawing substituents prefer do nucleophilic reactions on their Si4 and Si3 positions, respectively.Keywords: Density functional theory, Hexasiline, Reactivity, Benzene silicon analogs, Structural properties
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In this work, the effects of strontium addition on the structure and optical properties of nanostructured bismuth silicate (Bi4Si3O12) thin films prepared via sol-gel were studied. At first, different sols containing the optimum ratio of precursors were synthesized, and then, the prepared sols were coated on the substrate via dip coating. The dip coated samples were dried at 100oC and, in order to obtain the crystalline structure, calcination was done at 700 oC for 1 h. The prepared thin films were characterized and analyzed via scanning electron microscope (SEM), energy dispersive spectroscopy (EDS), atomic force microscope (AFM), and X-ray diffraction (XRD) analyses as well as ultraviolet-visible spectroscopy. The results showed that a homogeneous coating of bismuth silicate with the grain size in the range 35-50 nm could be formed. XRD analysis demonstrated the annealed sample at 700 oC composed of crystalline Bi4Si3O12 phase without any secondary phase. Investigation of the optical properties of the prepared thin films revealed that the addition of strontium decreased transparency from 82 to 78% and band gap from 3.61 to 3.32 eV.Keywords: Bi4Si3O12, Nanostructured coat, Optical properties, Strontium, Structural properties
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In this paper, La0.55Ca0.45A0.5Co0.5O3(A=Mg, Mn) nanoparticles were synthesized by citratemethod. The samples were characterized using the techniques of using X-ray diffraction(XRD), transmission electron microscopy (TEM), Fourier transform infrared (FTIR) and UVVisspectroscopy. The structure was analyzed by Rietveld fitting of the XRD pattern by usingX’Pert package and Fullprof program, these shows that the samples have perovskite structure.The calculated values of crystallite size, particle size and band gap energy of La0.55Ca0.45Mg0.5Co0.5O3 are much less than La0.55Ca0.45Mg0.5Co0.5O3. The effects of three operational parametersincluding irradiation time, pH, and the catalyst amount on the photocatalytic activity ofthe product on the degradation of methyl blue (MB) under solar condition were studied. Thephotocatalytic degradation efficiency of MB solution over La0.55Ca0.45Mn0.5Co0.5O3 nanoparticlesis higher than that over La0.55Ca0.45Mg0.5Co0.5O3 nanoparticles. 96 % degradation is obtainedin an aqueous solution at pH=2.33 and containing 30 mg La0.55Ca0.45Mg0.5Co0.5O3 catalystafter 30 minutes.
Keywords: nanoparticles, Cobaltite Perovskite, Structural Properties, UV-Visible, Photo-Degradation -
In this article, ZnO and ZnO:Mn nanoparticles prepared by reverse micelle method. The various crystalline properties of these nanoparticles such as size, d-spacing, strain, stress, dislocation density and texture coefficient have been calculated with the help of XRD spectrum. The XRD results indicated that the synthesized ZnO and ZnO:Mn nanoparticles have a pure wurtzite (hexagonal phase) structure. It can be seen that the highest texture coefficient was in (002) plan for nanoparticles. The optical band gap energy of ZnO and ZnO:Mn nanoparticles have been analyzed by using UV-Vis data. The photoluminescence spectra of the nanoparticles indicated their high structural and optical quality.Keywords: ZnO, Nanoparticles, Reverse micelle, Structural properties, Photoluminescence
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