scholarly journals Toward the Continuous Production of Multigram Quantities of Highly Uniform Supported Metallic Nanoparticles and Their Application for Synthesis of Superior Intermetallic Pt-Alloy ORR Electrocatalysts

2021 ◽  
Author(s):  
Luka Pavko ◽  
Matija Gatalo ◽  
Gregor Križan ◽  
Janez Križan ◽  
Konrad Ehelebe ◽  
...  
Keyword(s):  
Metallic Nanoparticles ◽  
Continuous Production ◽  
Pt Alloy ◽  
Highly Uniform

A Metastable Crystalline Phase Coexisted with the Decagonal Quasicrystals in Rapidly Solidified Al-Ir Al-Pd and Al-Pt Alloys

1990 ◽  
Vol 48 (1) ◽  
pp. 572-573
Author(s):  
Wang Rong ◽  
Ma Lina ◽  
K.H. Kuo
Keyword(s):  
Metastable Phase ◽  
Hexagonal Phase ◽  
Icosahedral Quasicrystal ◽  
Decagonal Quasicrystal ◽  
Decagonal Phase ◽  
Decagonal Quasicrystals ◽  
Pt Alloy ◽  
Pt Alloys ◽  
Diffraction Patterns ◽  
Rapidly Solidified

Up to now, decagonal quasicrystals have been found in the alloys of whole Al-Pt group metals [1,2]. The present paper is concerned with the TEM study of a hitherto unreported hexagonal phase in rapidly solidified Al-Ir, Al-Pd and Al-Pt alloys.The ribbons of Al5Ir, Al5Pd and Al5Pt were obtained by spun-quenching. Specimens cut from the ribbons were ion thinned and examined in a JEM 100CX electron microscope. In both rapidly solidified Al5Ir and Al5Pd alloys, the decagonal quasicrystal, with rosette or dendritic morphologies can be easily identified by its electron diffraction patterns(EDPs). The EDPs of the decagonal phase for the two alloys are quite similar. However, the existance of decagonal quasicrystal in the Al-Pt alloy has not been verified by our TEM study. It is probably for the reason that the cooling rate is not great enough for the Al5Pt alloy to form the decagonal phase. During the TEM study, a metastable hexagonal phase has been observed in the Al5Ir, Al5Pd and Al5Pt alloys. The lattic parameters calculated from the X-ray powder data of this phase are a=1.229 and c=2.647nm(Al-Pd) and a=1.231 and c=2.623nm(Al-Ir). The composition of this phase was determined by EDS analysis as Al4(Ir, Pd or Pt). It coexists with the decagonal phase in the alloys and transformed to other stable crystalline phases on heating to high temperature. A comparison between the EDPs of the hexagonal and the decagonal phase are shown in Fig.l. Fig. 1(a) is the EDPs of the decagonal phase in various orientions and the EDPs of the hexagonal phase are shown in Fig.1(b), in a similar arrangement as Fig.1(a). It can be clearly seen that the EDPs of the hexagonal phase, especially the distribution of strong spots, are quite similar to their partners of the decagonal quasicrystal in Fig.1(a). All the angles, shown in Fig.l, between two corresponding EDPs are very close to each other. All of these seem strongly to point out that a close structural relationshipexists between these two phases:[110]//d10 [001]//d2(D) //d2 (P)The structure of α-AlFeSi is well known [3] and the 54-atom Mackay icosahedron with double icosahedral shells in the α-AlFeSi structure [4] have been used to model the icosahedral quasicrystal structure. Fig.2(a) and (b) show, respectively, the [110] and [001] projections of the crystal structure of α- AlFeSi, and decagon-pentagons can easily be identified in the former and hexagons in the latter. In addition, the optical transforms of these projections show clearly decagons and hexagons of strong spots, quite similar to those in [110] and [001] EDPs in Fig.1(b). This not only proves the Al(Ir, Pt, Pd) metastable phase being icostructural with the α-AlFeSi phase but also explains the orientation relationship mentioned above.

Plasmon-assisted interaction of Si with light, for cancer hyperthermia and electromagnetic energy harvest

2020 ◽  
Vol 92 (2) ◽  
pp. 20101
Author(s):  
Behnam Kheyraddini Mousavi ◽  
Morteza Rezaei Talarposhti ◽  
Farshid Karbassian ◽  
Arash Kheyraddini Mousavi
Keyword(s):  
Silicon Nanowires ◽  
Metallic Nanoparticles ◽  
Near Infrared ◽  
Optical Transition ◽  
Electromagnetic Energy ◽  
Energy Harvest ◽  
Absorption Enhancement ◽  
Ir Absorption ◽  
Absorption Mechanism ◽  
Near Ir

Metal-assisted chemical etching (MACE) is applied for fabrication of silicon nanowires (SiNWs). We have shown the effect of amorphous sheath of SiNWs by treating the nanowires with SF6 and the resulting reduction of absorption bandwidth, i.e. making SiNWs semi-transparent in near-infrared (IR). For the first time, by treating the fabricated SiNWs with copper containing HF∕H2O2∕H2O solution, we have generated crystalline nanowires with broader light absorption spectrum, up to λ = 1 μm. Both the absorption and photo-luminescence (PL) of the SiNWs are observed from visible to IR wavelengths. It is found that the SiNWs have PL at visible and near Infrared wavelengths, which may infer presence of mechanisms such as forbidden gap transitions other can involvement of plasmonic resonances. Non-radiative recombination of excitons is one of the reasons behind absorption of SiNWs. Also, on the dielectric metal interface, the absorption mechanism can be due to plasmonic dissipation or plasmon-assisted generation of excitons in the indirect band-gap material. Comparison between nanowires with and without metallic nanoparticles has revealed the effect of nanoparticles on absorption enhancement. The broader near IR absorption, paves the way for applications like hyperthermia of cancer while the optical transition in near IR also facilitates harvesting electromagnetic energy at a broad spectrum from visible to IR.

Green synthesis of mixed metallic nanoparticles using room temperature self-assembly

2017 ◽  
Vol 13 (2) ◽  
pp. 4671-4677 ◽  
Author(s):  
A. M. Abdelghany ◽  
A.H. Oraby ◽  
Awatif A Hindi ◽  
Doaa M El-Nagar ◽  
Fathia S Alhakami
Keyword(s):  
Self Assembly ◽  
Metallic Nanoparticles ◽  
Room Temperature ◽  
Bimetallic Nanoparticles ◽  
Reduction Process ◽  
Nano Particles ◽  
Nano Structure ◽  
Small Shift ◽  
Molar Ratios ◽  
Vis Spectroscopy

Bimetallic nanoparticles of silver (Ag) and gold (Au) were synthesized at room temperature using Curcumin. Reduction process of silver and gold ions with different molar ratios leads to production of different nanostructures including alloys and core-shells. Produced nanoparticles were characterized simultaneously with FTIR, UV/vis. spectroscopy, transmission electron microscopy (TEM), and Energy-dispersive X-ray (EDAX). UV/vis. optical absorption spectra of as synthesized nanoparticles reveals presence of surface palsmon resonance (SPR) of both silver at (425 nm) and gold at (540 nm) with small shift and broadness of gold band after mixing with resucing and capping agent in natural extract which suggest presence of bimetallic nano structure (Au/Ag). FTIR and EDAX data approve the presence of bimetallic nano structure combined with curcumin extract. TEM micrographs shows that silver and gold can be synthesized separately in the form of nano particles using curcumin extract. Synthesis of gold nano particles in presence of silver effectively enhance and control formation of bi-metallic structure.

Metallic Nanoparticle Synthesis by Green Chemistry

2018 ◽  
Vol 11 (6) ◽  
pp. 4287-4294
Author(s):  
Anikate Sood ◽  
Shweta Agarwal
Keyword(s):  
Green Chemistry ◽  
Green Synthesis ◽  
Biomedical Research ◽  
Metallic Nanoparticles ◽  
Nanoparticle Synthesis ◽  
Synthesis Methods ◽  
Metallic Nanoparticle ◽  
Medical Field ◽  
Advantages And Disadvantages ◽  
Gold Silver

Nanotechnology is the most sought field in biomedical research. Metallic nanoparticles have wide applications in the medical field and have gained the attention of various researchers for advanced research for their application in pharmaceutical field. A variety of metallic nanoparticles like gold, silver, platinum, palladium, copper and zinc have been developed so far. There are different methods to synthesize metallic nanoparticles like chemical, physical, and green synthesis methods. Chemical and physical approaches suffer from certain drawbacks whereas green synthesis is emerging as a nontoxic and eco-friendly approach in production of metallic nanoparticles. Green synthesis is further divided into different approaches like synthesis via bacteria, fungi, algae, and plants. These approaches have their own advantages and disadvantages. In this article, we have described various metallic nanoparticles, different modes of green synthesis and brief description about different metabolites present in plant that act as reducing agents in green synthesis of metallic nanoparticles. 

OPERATION OF EQUIPMENT IN CONTINUOUS PRODUCTION

2020 ◽  
Author(s):  
Сергей Ильдусович Валеев
Keyword(s):  
Continuous Production ◽  
Subsequent Development

В работе проведен анализ возможной эксплуатации сосудов и аппаратов с дефектами типа расслоение. Установлено, что эксплуатация оборудования возможна только с последующей разработкой мероприятий, позволяющих повысить уровень безопасности. The paper analyzes the possible operation of vessels and apparatuses with defects of the stratification type. It was established that the operation of the equipment is possible only with the subsequent development of measures to increase the level of safety.

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