scholarly journals Room-Temperature Synthesis of Ni and Pt-Co Alloy Nanoparticles Using a Microreactor

2021 ◽  
Vol 3 ◽  
Author(s):  
Satoshi Watanabe ◽  
Tomohiro Koshiyama ◽  
Takeshi Watanabe ◽  
Minoru T. Miyahara
Keyword(s):  
Chemical Reactions ◽  
Room Temperature ◽  
Small Degree ◽  
Potential Productivity ◽  
Synthetic Process ◽  
Precise Control ◽  
Batch Type ◽  
Bimetallic System ◽  
Materials Used ◽  
Average Size

Metal nanoparticles (NPs) are key materials used in a broad range of industries. Among the various synthetic routes of NPs, liquid-phase chemical reactions are promising because of their versatility in reaction conditions as well as their potential productivity. However, because the synthesis of NPs involves not only chemical reactions but also nucleation and growth processes, which are typically higher-order reactions in terms of the concentration, a small degree of nonuniformity in the concentration during mixing of reaction solutions can easily result in a wide size distribution of the resultant particles. A typical solution to this problem is to slow the rate of reactions compared with that of mixing; however, as a result, the synthetic processes often require long reaction periods and complex procedures. In this study, we applied a microreactor with excellent mixing performance to NP synthesis to simplify and intensify the processes. We synthesized nickel and platinum-cobalt alloy NPs as model materials. For the Ni NP synthesis, we demonstrated that the quick mixing provided by the microreactor enabled the precise control of the residence time, and consequently, monodispersed Ni NPs with an average size of 3.8 nm were synthesized. For the Pt-Co bimetallic system, the microreactor successfully produced Pt-Co alloy NPs, while batch-type synthesis with weaker mixing intensity resulted in a bimodal mixture of larger Pt NPs and smaller Co NPs. For both Ni and Pt-Co, monodispersed NPs were synthesized by simply mixing the reaction solutions in the microreactor at room temperature. These results demonstrate that the mixing process plays a key role in NP synthesis, and application of a microreactor enables the establishment of a facile and robust synthetic process.

scholarly journals Precise Control of CsPbBr3 Perovskite Nanocrystal Growth at Room Temperature: Size Tunability and Synthetic Insights

2021 ◽  
Vol 33 (7) ◽  
pp. 2387-2397
Author(s):  
Alasdair A. M. Brown ◽  
Parth Vashishtha ◽  
Thomas J. N. Hooper ◽  
Yan Fong Ng ◽  
Gautam V. Nutan ◽  
...  
Keyword(s):  
Room Temperature ◽  
Precise Control ◽  
Nanocrystal Growth

scholarly journals Mid infrared polarization engineering via sub-wavelength biaxial hyperbolic van der Waals crystals

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Saurabh Dixit ◽  
Nihar Ranjan Sahoo ◽  
Abhishek Mall ◽  
Anshuman Kumar
Keyword(s):  
Room Temperature ◽  
Extinction Ratio ◽  
Polarization State ◽  
Van Der Waals ◽  
Photonic Devices ◽  
Mid Infrared ◽  
Precise Control ◽  
Electromagnetic Simulations ◽  
Frequency Regime ◽  
Sub Wavelength

AbstractMid-infrared (IR) spectral region is of immense importance for astronomy, medical diagnosis, security and imaging due to the existence of the vibrational modes of many important molecules in this spectral range. Therefore, there is a particular interest in miniaturization and integration of IR optical components. To this end, 2D van der Waals (vdW) crystals have shown great potential owing to their ease of integration with other optoelectronic platforms and room temperature operation. Recently, 2D vdW crystals of $$\alpha$$ α -$$\hbox {MoO}_{3}$$ MoO 3 and $$\alpha$$ α -$$\hbox {V}_2 \hbox {O}_5$$ V 2 O 5 have been shown to possess the unique phenomenon of natural in-plane biaxial hyperbolicity in the mid-infrared frequency regime at room temperature. Here, we report a unique application of this in-plane hyperbolicity for designing highly efficient, lithography free and extremely subwavelength mid-IR photonic devices for polarization engineering. In particular, we show the possibility of a significant reduction in the device footprint while maintaining an enormous extinction ratio from $$\alpha$$ α -$$\hbox {MoO}_{3}$$ MoO 3 and $$\alpha$$ α -$$\hbox {V}_2$$ V 2 $$\hbox {O}_5$$ O 5 based mid-IR polarizers. Furthermore, we investigate the application of sub-wavelength thin films of these vdW crystals towards engineering the polarization state of incident mid-IR light via precise control of polarization rotation, ellipticity and relative phase. We explain our results using natural in-plane hyperbolic anisotropy of $$\alpha$$ α -$$\hbox {MoO}_{3}$$ MoO 3 and $$\alpha$$ α -$$\hbox {V}_2$$ V 2 $$\hbox {O}_5$$ O 5 via both analytical and full-wave electromagnetic simulations. This work provides a lithography free alternative for miniaturized mid-infrared photonic devices using the hyperbolic anisotropy of $$\alpha$$ α -$$\hbox {MoO}_{3}$$ MoO 3 and $$\alpha$$ α -$$\hbox {V}_2$$ V 2 $$\hbox {O}_5$$ O 5 .

scholarly journals Room Temperature Syntheses of ZnO and Their Structures

Symmetry ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 733
Author(s):  
Domenica Donia ◽  
Elvira Maria Bauer ◽  
Mauro Missori ◽  
Ludovica Roselli ◽  
Daniele Cecchetti ◽  
...  
Keyword(s):  
Room Temperature ◽  
Direct Synthesis ◽  
Threshold Value ◽  
Rietveld Analysis ◽  
Synthesis Temperature ◽  
Density Variation ◽  
Controlled Synthesis ◽  
Sem Images ◽  
Aqueous Solvent ◽  
Average Size

ZnO has many technological applications which largely depend on its properties, which can be tuned by controlled synthesis. Ideally, the most convenient ZnO synthesis is carried out at room temperature in an aqueous solvent. However, the correct temperature values are often loosely defined. In the current paper, we performed the synthesis of ZnO in an aqueous solvent by varying the reaction and drying temperatures by 10 °C steps, and we monitored the synthesis products primarily by XRD). We found out that a simple direct synthesis of ZnO, without additional surfactant, pumping, or freezing, required both a reaction (TP) and a drying (TD) temperature of 40 °C. Higher temperatures also afforded ZnO, but lowering any of the TP or TD below the threshold value resulted either in the achievement of Zn(OH)2 or a mixture of Zn(OH)2/ZnO. A more detailed Rietveld analysis of the ZnO samples revealed a density variation of about 4% (5.44 to 5.68 gcm−3) with the synthesis temperature, and an increase of the nanoparticles’ average size, which was also verified by SEM images. The average size of the ZnO synthesized at TP = TD = 40 °C was 42 nm, as estimated by XRD, and 53 ± 10 nm, as estimated by SEM. For higher synthesis temperatures, they vary between 76 nm and 71 nm (XRD estimate) or 65 ± 12 nm and 69 ± 11 nm (SEM estimate) for TP =50 °C, TD = 40 °C, or TP = TD = 60 °C, respectively. At TP = TD = 30 °C, micrometric structures aggregated in foils are obtained, which segregate nanoparticles of ZnO if TD is raised to 40 °C. The optical properties of ZnO obtained by UV-Vis reflectance spectroscopy indicate a red shift of the band gap by ~0.1 eV.

Studies Concerning the Corrosion Behaviour of the Cast Stainless Steel Used for Chemical Industry

2013 ◽  
Vol 371 ◽  
pp. 338-342
Author(s):  
Gheorghe Simionescu ◽  
Mirela Gheorghian
Keyword(s):  
Chemical Industry ◽  
Room Temperature ◽  
Corrosion Behaviour ◽  
Research Work ◽  
Experimental Tests ◽  
Hot Environment ◽  
Chemical Agents ◽  
The Subject ◽  
Materials Used ◽  
Cast Stainless Steel

The current work deals with experimental tests concerning the behaviour of different materials used in chemical industry when are exposed to diverse corrosions environments. During the research work four different metals have been tested, namely T15NiCr180, T15MoNiCr180, W4027 and W4059. The presented work is trying to classify the tested materials function to different chemical environment, different concentration of the environment, different temperature of the environment, and different expose time. Some of the substances which were considered as corrosion environment are: HNO3, H3PO4, NaCl, NH4Cl, C2H5OH, Petrol, NH4NO3, KNO3, K2CO3, Na2CO3, KMnO4, KOH and Ca (OH)2. The concentration of the corrosion solutions varies between 1% and 96%. Tests have been done at room temperature and hot environment of 100°C. Time is playing an important role on evolution of the corrosion. For this reason the samples have been analyzed after 48, 336, 720 and 2160 hours of exposes to chemical agents. To understand the comportment of the subject metals when are used in industry, samples have been tested for longer period of time, respectively 1, 3, 6 and 12 months. After each selected period of time the metallic samples were analyzed and measured to quantify the effect of the environment on the corrosion speed.

Versatile Dual Photoresponsive System for Precise Control of Chemical Reactions

ACS Nano ◽  
2017 ◽  
Vol 11 (8) ◽  
pp. 7770-7780 ◽  
Author(s):  
Can Xu ◽  
Wei Bing ◽  
Faming Wang ◽  
Jinsong Ren ◽  
Xiaogang Qu
Keyword(s):  
Chemical Reactions ◽  
Precise Control

scholarly journals Evaluation of Pre-heating Effects on Marginal Adaptation of Resin-based Materials

2018 ◽  
Vol 55 (2) ◽  
pp. 238-242 ◽  
Author(s):  
Ionut Taraboanta ◽  
Simona Stoleriu ◽  
Gianina Iovan ◽  
Antonia Moldovanu ◽  
Andrei Georgescu ◽  
...  
Keyword(s):  
Room Temperature ◽  
Composite Resin ◽  
Optical Microscope ◽  
Marginal Adaptation ◽  
Gap Formation ◽  
Solution Ph ◽  
Filling Materials ◽  
Heating Effects ◽  
Direct Restoration ◽  
Materials Used

The aim of the study was to compare the marginal adaptation of three different resin-based materials used for direct restoration: hybrid composite resin (Gaenial Posterio, GC Corporation), a compomer (Dyract eXtra, Dentsply Sirona), and a giomer (Beautifil II, Shofu Dental) applied at room temperature or after preheated at preheating 50 and 60oC. Class II cavities were prepared on proximal surfaces of extracted teeth and randomly divided in 3 groups according to the material used for restoration. In each group five cavities were restored using the materials at room temperature (subgroup 1), five cavities were restored using preheated materials at 50şC (subgroup 2), and five cavities were restored using preheated materials at 60şC (subgroup 3). The teeth were stored in distilled water for 14 days and then were immersed in 2% methylene blue buffered dye solution (pH = 7) for 4 hours. The teeth were transversally cut and the sections were examined using optical microscope (Carl-Zeiss AXIO Imager A1m) at 50x magnification and the dye penetration was evaluated according to 4 scores. Decreased microleakage and fewer gap formation were recorded for all filling materials after they have been heated at 50 or 60oC. Pre-warming of resin-based materials improves the adaptation of these materials to tooth structures.

scholarly journals CHARACTERISTICS OF LITHIUM LANTHANUM TITANATE THIN FILMS MADE BY ELECTRON BEAM EVAPORATION FROM NANOSTRUCTURED La0.67-xLi 3xTiO3 TARGET

2017 ◽  
Vol 25 (2) ◽  
pp. 243-250
Author(s):  
Nguyen Nang Dinh ◽  
Le Dinh Trong ◽  
Pham Duy Long
Keyword(s):  
Thin Films ◽  
Electron Beam ◽  
Ionic Conductivity ◽  
Room Temperature ◽  
Xrd Analysis ◽  
Electron Beam Evaporation ◽  
Electrochromic Devices ◽  
Lanthanum Titanate ◽  
Average Size ◽  
Beam Deposition

Bulk nanostructured perovskites of La0.67-xLi3xTiO3 (LLTO) were prepared by using thermally ball-grinding from compounds of La2O3, Li2CO3 and TiO2. From XRD analysis, it was found that LTTO materials were crystallized with nano-size grains of an average size of 30 nm. The bulk ionic conductivity was found strongly dependent on the Li+ composition, the samples with x = 0.11 (corresponding to a La0.56Li0.33TiO3 compound) have the best ionic conductivity, which is ca. 3.2 x 10-3 S/cm at room temperature. The LLTO amorphous films were made by electron beam deposition. At room temperature the smooth films have ionic conductivity of 3.5 x 10-5  S/cm and transmittance of 80%. The optical bandgap of the films was found to be of 2.3 eV. The results have shown that the perovskite La0.56Li0.33TiO3  thin films can be used for a transparent solid electrolyte in ionic battery and in all-solid-state electrochromic devices, in particular.    

LOW LOSS DIELECTRIC MATERIALS FOR HIGH FREQUENCY APPLICATIONS

2009 ◽  
Vol 23 (17) ◽  
pp. 3649-3654 ◽  
Author(s):  
MOHAN V. JACOB
Keyword(s):  
High Frequency ◽  
Room Temperature ◽  
Low Cost ◽  
Dielectric Materials ◽  
Dielectric Constants ◽  
Transmission Losses ◽  
Low Loss ◽  
Microwave Characterization ◽  
Materials Used ◽  
Low Temperature Electronics

The microwave properties of some of the low cost materials which can be used in high frequency applications with low transmission losses are investigated in this paper. One of the most accurate microwave characterization techniques, Split Post Dielectric Resonator technique (SPDR) is used for the experimental investigation. The dielectric constants of the 3 materials scrutinized at room temperature and at 10K are 3.65, 2.42, 3.61 and 3.58, 2.48, 3.59 respectively. The corresponding loss tangent values are 0.00370, 0.0015, 0.0042 and 0.0025, 0.0009, 0.0025. The high frequency transmission losses are comparable with many of the conventional materials used in low temperature electronics and hence these materials could be implemented in such applications.

Effect of current density on the porous silicon preparation as gas sensors**

2021 ◽  
Vol 30 (1) ◽  
pp. 257-264
Author(s):  
Muna H. Kareem ◽  
Adi M. Abdul Hussein ◽  
Haitham Talib Hussein
Keyword(s):  
Porous Silicon ◽  
Gas Sensors ◽  
Current Density ◽  
Room Temperature ◽  
Low Cost ◽  
High Surface ◽  
Volume Ratio ◽  
Etching Time ◽  
Force Microscopy ◽  
Materials Used

Abstract In this study, porous silicon (PSi) was used to manufacture gas sensors for acetone and ethanol. Samples of PSi were successfully prepared by photoelectrochemical etching and applied as an acetone and ethanol gas sensor at room temperature at various current densities J= 12, 24 and 30 mA/cm2 with an etching time of 10 min and hydrofluoric acid concentration of 40%. Well-ordered n-type PSi (100) was carefully studied for its chemical composition, surface structure and bond configuration of the surface via X-ray diffraction, atomic force microscopy, Fourier transform infrared spectroscopy and photoluminescence tests. Results showed that the best sensitivity of PSi was to acetone gas than to ethanol under the same conditions at an etching current density of 30 mA/cm2, reaching about 2.413 at a concentration of 500 parts per million. The PSi layers served as low-cost and high-quality acetone gas sensors. Thus, PSi can be used to replace expensive materials used in gas sensors that function at low temperatures, including room temperature. The material has an exceptionally high surface-to-volume ratio (increasing surface area) and demonstrates ease of fabrication and compatibility with manufacturing processes of silicon microelectronics.

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