Prenylation of Quinonoid Compounds with Prenyl Bromide Using Lead Bromide/Aluminum Powder as Catalyst

1990 ◽  
Vol 20 (12) ◽  
pp. 1743-1749 ◽  
Author(s):  
R. N. Khanna ◽  
Prem Kumar Singh
Keyword(s):  
Aluminum Powder ◽  
Lead Bromide

Elucidating the Weakly Reversible Cs-Pb-Br Perovskite Nanocrystal Reaction Network with High-Throughput Maps and Transformations

2020 ◽  
Author(s):  
Jakob Dahl ◽  
Xingzhi Wang ◽  
Xiao Huang ◽  
Emory Chan ◽  
Paul Alivisatos
Keyword(s):  
High Throughput ◽  
Dynamic Equilibrium ◽  
Reaction Network ◽  
Substantial Impact ◽  
Equilibrium Behavior ◽  
Automated Method ◽  
Lead Bromide ◽  
Different Shapes ◽  
Complex Chemistry ◽  
Lead Halide

<p>Advances in automation and data analytics can aid exploration of the complex chemistry of nanoparticles. Lead halide perovskite colloidal nanocrystals provide an interesting proving ground: there are reports of many different phases and transformations, which has made it hard to form a coherent conceptual framework for their controlled formation through traditional methods. In this work, we systematically explore the portion of Cs-Pb-Br synthesis space in which many optically distinguishable species are formed using high-throughput robotic synthesis to understand their formation reactions. We deploy an automated method that allows us to determine the relative amount of absorbance that can be attributed to each species in order to create maps of the synthetic space. These in turn facilitate improved understanding of the interplay between kinetic and thermodynamic factors that underlie which combination of species are likely to be prevalent under a given set of conditions. Based on these maps, we test potential transformation routes between perovskite nanocrystals of different shapes and phases. We find that shape is determined kinetically, but many reactions between different phases show equilibrium behavior. We demonstrate a dynamic equilibrium between complexes, monolayers and nanocrystals of lead bromide, with substantial impact on the reaction outcomes. This allows us to construct a chemical reaction network that qualitatively explains our results as well as previous reports and can serve as a guide for those seeking to prepare a particular composition and shape. </p>

Hollow Metal Halide Perovskite Nanocrystals with Efficient Blue Emissions

2019 ◽  
Author(s):  
Michael Worku ◽  
Yu Tian ◽  
Chenkun Zhou ◽  
Haoran Lin ◽  
Maya Chaaban ◽  
...  
Keyword(s):  
Precursor Solution ◽  
Visible Spectral Region ◽  
Metal Halide ◽  
Synthetic Control ◽  
Perovskite Nanocrystals ◽  
Highly Efficient ◽  
Quantum Confinement Effects ◽  
Metal Halide Perovskite ◽  
Lead Bromide ◽  
Halide Perovskite

Metal halide perovskite nanocrystals (NCs) have emerged as a new generation light emitting materials with narrow emissions and high photoluminescence quantum efficiencies (PLQEs). Various types of perovskite NCs, e.g. platelets, wires, and cubes, have been discovered to exhibit tunable emissions across the whole visible spectral region. Despite remarkable advances in the field of metal halide perovskite NCs over the last few years, many nanostructures in inorganic NCs have yet been realized in metal halide perovskites and producing highly efficient blue emitting perovskite NCs remains challenging and of great interest. Here we report for the first time the discovery of highly efficient blue emitting cesium lead bromide perovskite (CsPbBr3) NCs with hollow structures. By facile solution processing of cesium lead bromide perovskite precursor solution containing additional ethylenediammonium bromide and sodium bromide, in-situ formation of hollow CsPbBr3 NCs with controlled particle and pore sizes is realized. Synthetic control of hollow nanostructures with quantum confinement effects results in color tuning of CsPbBr3 NCs from green to blue with high PLQEs of up to 81 %.<br><div><br></div>

INFLUENCE OF FLOW SWIRLING ON COMBUSTION OF ALUMINUM POWDER AEROSUSPENSION IN A CHAMBER WITH EXTENSION

2020 ◽  
Author(s):  
A. Yu. Krainov ◽  
◽  
K. M. Moiseeva ◽  
V. A. Poryazov ◽  
◽  
...  
Keyword(s):  
Dynamic Model ◽  
Aluminum Powder ◽  
Swirling Flow ◽  
Numerical Study ◽  
Mathematical Formulation ◽  
Expansion Chamber ◽  
Flow Swirling ◽  
Air Suspension

A numerical study of combustion of the aluminum-air suspension in the swirling flow in the expansion chamber has been performed. The physical and mathematical formulation of the problem is based on the dynamic model of the multiphase reacting media.

Technology for producing composite nanostructured powder for protective coatings

2020 ◽  
pp. 97-103
Author(s):  
E. Yu. Geraschenkova ◽  
A. F. Vasiliev ◽  
E. A. Samodelkin ◽  
B. V. Farmakovsky
Keyword(s):  
Aluminum Powder ◽  
High Speed ◽  
Protective Coatings ◽  
Hadfield Steel ◽  
Nanostructured Powder ◽  
Powder Composition ◽  
Clad Powder

This article presents the results of the development of technology for producing clad powder and coatings based on it. The possibility of obtaining a clad powder using high-speed mechanosynthesis in disintegrator plants is shown on the example of the Hadfield steel – aluminum powder composition.

Environmental Sustainability through Recycling Incineration Bottom Ash for the Production of Autoclaved Aerated Concrete

2015 ◽  
Vol 650 ◽  
pp. 51-70 ◽  
Author(s):  
En Hua Yang ◽  
Yi Quan Liu ◽  
Zhi Tao Chen
Keyword(s):  
Aluminum Powder ◽  
Environmental Sustainability ◽  
Pure Aluminum ◽  
Bottom Ash ◽  
Waste Incineration ◽  
Gas Generation ◽  
Autoclaved Aerated Concrete ◽  
Silica Source ◽  
Aerated Concrete ◽  
Aeration Capacity

Municipal solid waste incineration bottom ash (IBA) has great potential to be utilized for civil engineering applications. This paper is to investigate the characteristic of gas generation from IBA and to study the potential of IBA as aerating agent to replace costly aluminum powder and as silica source to partially replace silica flour/fly ash in the production of autoclaved aerated concrete (AAC). Results show the aeration capacity of IBA used in this study is about 1% that of pure aluminum powder by mass. Finer particles, higher alkali molarity, and higher reaction temperature encourage the reaction and more gas is generated per gram of IBA. Type of alkaline solution does not seem to be an important factor for gas generation from IBA. Several exemplary lightweight mortars and AACs were produced by incorporating IBA as aerating agent. It is highly plausible IBA can be used as aerating agent to replace pure aluminum powder in the production of normal aerated concrete. IBA-AACs with density ranging from 600 to 800 kg/m3 were successfully synthesized by using IBA as aerating agent. For a given density, the compressive strength of IBA-AAC is higher than that of AAC due to the formation of more uniform pore structure with smaller pore size in IBA-AAC.

Bromopropane as a Novel Bromine Precursor for the Completely Amine Free Colloidal Synthesis of Ultra-Stable and Highly Luminescent Green-Emitting Cesium Lead Bromide (CsPbBr3) Perovskite Nanocrystals

Nanoscale ◽  
2021 ◽  
Author(s):  
Syed Akhil ◽  
V.G.Vasavi Dutt ◽  
Nimai Mishra
Keyword(s):  
Optoelectronic Devices ◽  
Colloidal Synthesis ◽  
Ambient Conditions ◽  
Active Materials ◽  
Perovskite Nanocrystals ◽  
Lead Bromide ◽  
Halide Perovskite ◽  
Lead Halide ◽  
Poor Stability

Recently lead halide perovskite nanocrystals (PNCs) have attracted intense interest as promising active materials for optoelectronic devices. However, their extensive applications are still hampered by poor stability in ambient conditions....

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