Sensing behavior of perovskites GdCo1−xCuxO3 prepared by solution and ultrasonic-assisted aerosol methods.

2004 ◽  
Vol 828 ◽  
Author(s):  
Carlos R. Michel ◽  
Edgar R. López ◽  
Arturo Chávez
Keyword(s):  
Aqueous Solutions ◽  
Solution Method ◽  
Spherical Particles ◽  
Electrical Measurements ◽  
Gas Sensitivity ◽  
Semiconductor Behavior ◽  
Ultrasonic Assisted ◽  
Method Yield ◽  
Precursor Powders ◽  
Made In

ABSTRACTPolycrystalline samples of GdCo1−xCuxO3 (x=0, 0.15, 0.3), were prepared by two different routes: solution and ultrasonic-assisted aerosol decomposition. For both procedures, aqueous solutions containing stoichiometric amounts of Gd(NO3)36H2O, Co(NO3)26H2O and Cu(NO3)22.5H2O were used. In the solution method, the aqueous solutions were heat-dried at 76°C obtaining precursor powders, these were calcined from 80 to 950°C, in air. In the aerosol method, very small droplets were produced by an ultrasonic generator, then a flow of oxygen transported the mist through a tubular furnace, previously heated at 950°C. Solvent evaporation and chemical reaction takes place at that temperature, and the resulting powder was collected by filtration. X-ray powder diffraction was used to identify the formation of target phases. Surface microstructure of powders was analyzed by SEM, and showed that solution method produced sub-micron particles with irregular shape, whereas the aerosol method yield micron-sized hollow spherical particles. In order to determine gas sensitivity vs. temperature, electrical measurements were made in air, O2 and CO2, from room temperature to 650°C. The results showed a semiconductor behavior and a moderate gas sensitivity for samples prepared by solution method. However, unreliable data were registered for samples made by the aerosol route, caused by short connectivity between particles.

Sensing Properties of Nanostructured Sm1-xBaxCoO3 (x = 0, 0.1) obtained by Solution Method

2005 ◽  
Vol 876 ◽  
Author(s):  
Carlos R. Michel ◽  
Emilio Delgado ◽  
Israel Ceja
Keyword(s):  
Solution Method ◽  
X Ray Diffraction ◽  
Electrical Measurements ◽  
Separation Membranes ◽  
Gas Separation Membranes ◽  
Semiconductor Behavior ◽  
Diffraction Patterns ◽  
Perovskite Type ◽  
Microscopy Images ◽  
Made In

AbstractSome cobaltites with perovskite-type structure exhibit outstanding transport properties and high chemical activity, which make these materials suitable for applications in areas of gas sensors, heterogeneous catalysis, gas separation membranes and cathodes for solid oxide fuel cells. In this work, polycrystalline samples of Sm1-xBaxCoO3 (x = 0, 0.1) were prepared by an aqueous solution method using the corresponding nitrates. X-ray diffraction patterns of calcined samples showed that single-phase SmCoO3 was obtained at 900°C, whereas Sm0.9Ba0.1CoO3 was formed at 700°C. Electron microscopy images revealed that micron-sized particles were obtained for SmCoO3, whereas a nanostructured and nanoporous material wasobserved for Sm0.9Ba0.1CoO3. Electrical measurements made on thick films of the oxides revealed a semiconductor behavior in both phases, however Sm0.9Ba0.1CoO3 samples showed a larger conductivity compared with SmCoO3; dynamic response of resistance experiments made in air and CO2 revealed that Sm0.9Ba0.1CoO3 is selective to CO2.

scholarly journals Impurities and Homogeneous Crystal Nucleation in Aqueous Solutions - An Overview

2019 ◽  
Vol 16 (3) ◽  
pp. 198-208
Author(s):  
C. K. Mahadevan
Keyword(s):  
Aqueous Solution ◽  
Aqueous Solutions ◽  
Research Group ◽  
Present Author ◽  
Crystal Nucleation ◽  
Nucleation Process ◽  
Nucleation Parameters ◽  
The Past ◽  
Homogeneous Crystal ◽  
Made In

Nucleation process is the most important stage in the formation of a crystal and has attracted the attention of researchers due to its importance in many technological and biological contexts. As the presence of impurities affects the nucleation process significantly, several studies have been made in the past to understand it. In this article is presented an overview of various studies made to understand the effect of soluble impurities on the crystal nucleation parameters of certain important materials in aqueous solution focusing the results reported by the research group of the present author.

Simultaneous ultrasonic-assisted removal of malachite green and safranin O by copper nanowires loaded on activated carbon: central composite design optimization

RSC Advances ◽  
2015 ◽  
Vol 5 (70) ◽  
pp. 57021-57029 ◽  
Author(s):  
Mostafa Roosta ◽  
Mehrorang Ghaedi ◽  
Arash Asfaram
Keyword(s):  
Activated Carbon ◽  
Aqueous Solutions ◽  
Central Composite Design ◽  
Design Optimization ◽  
Malachite Green ◽  
Copper Nanowires ◽  
Ultrasonic Assisted ◽  
Ultrasound Assisted ◽  
Safranin O ◽  
Central Composite

The present study investigates the simultaneous ultrasound-assisted adsorption of malachite green (MG) and safranin O (SO) dyes from aqueous solutions by ultrasound-assisted adsorption onto copper nanowires loaded on activated carbon (Cu-NWs-AC).

Properties and Growth of MBE Grown Erbium Doped Gallium Arsenide Co-Doped with Selenium

1996 ◽  
Vol 422 ◽  
Author(s):  
P. Rutter ◽  
K. E. Singer ◽  
A. R. Peaker ◽  
A. C. Wright
Keyword(s):  
Electron Concentration ◽  
Flux Ratio ◽  
Growth Conditions ◽  
Deep Levels ◽  
Spherical Particles ◽  
Electrical Measurements ◽  
Erbium Doping ◽  
Measured Concentration ◽  
Erbium Doped ◽  
Co Doped

AbstractThe growth of erbium doped GaAs by molecular beam epitaxy (MBE) can, depending on growth conditions, result in the precipitation of small spherical particles of erbium arsenide. It has been observed that by reducing the V:III (As:Ga) flux ratio to close to stoichiometry wirelike precipitates roughly aligned in the direction of growth are produced. The concentration of erbium incorporated into the GaAs lattice for a constant erbium flux is also affected by the As:Ga flux ratio with an increase in erbium doping being observed with decreasing As:Ga flux ratio.Electrical measurements have been performed on erbium doped GaAs samples co-doped with selenium, an n-type dopant. Measurements have revealed that when erbium is present, the electron concentration is reduced by an amount approximately equal to 70% of the erbium concentration. DLTS measurements have shown that although large concentrations of deep levels are present in erbium doped material, the measured concentration of these deep levels is not high enough to account for the observed reduction in electron concentration with erbium doping.

scholarly journals Computation of the magnetic potential induced by a collection of spherical particles using series expansions

2020 ◽  
Vol 54 (4) ◽  
pp. 1073-1109
Author(s):  
Stéphane Balac ◽  
Laurent Chupin ◽  
Sébastien Martin
Keyword(s):  
Magnetic Field ◽  
Magnetic Potential ◽  
Point Of View ◽  
Spherical Particles ◽  
Main Magnetic Field ◽  
Minimal Distance ◽  
Metallic Particles ◽  
Scalar Magnetic Potential ◽  
The Magnetic Field ◽  
Made In

In Magnetic Resonance Imaging there are several situations where, for simulation purposes, one wants to compute the magnetic field induced by a cluster of small metallic particles. Given the difficulty of the problem from a numerical point of view, the simplifying assumption that the field due to each particle interacts only with the main magnetic field but does not interact with the fields due to the other particles is usually made. In this paper we investigate from a mathematical point of view the relevancy of this assumption and provide error estimates for the scalar magnetic potential in terms of the key parameter that is the minimal distance between the particles. A special attention is paid to obtain explicit and relevant constants in the estimates. When the “non-interacting assumption” is deficient, we propose to compute a better approximation of the magnetic potential by taking into account pairwise magnetic field interactions between particles that enters in a general framework for computing the scalar magnetic potential as a series expansion.

Fabrication of Dispersed Permalloy Nanoparticles by Pulsed Laser Ablation in Aqua

2008 ◽  
Vol 1118 ◽  
Author(s):  
Ruqiang Bao ◽  
Zijie Yan ◽  
Yong Huang ◽  
Douglas B. Chrisey
Keyword(s):  
Laser Ablation ◽  
Sodium Dodecyl Sulfate ◽  
Aqueous Solutions ◽  
Laser Energy ◽  
Sodium Dodecyl ◽  
Pulsed Laser ◽  
Pulsed Laser Ablation ◽  
Distilled Water ◽  
Pure Ethanol ◽  
Made In

ABSTRACTPermalloy (Ni81Fe19) nanoparticles with diameters of hundreds of nanometers have been successfully fabricated by pulsed laser ablation (PLA) in air, distilled water, pure ethanol and sodium dodecyl sulfate (SDS) aqueous solutions. The permalloy nanoparticles made in SDS solutions are typically spherical in shape. Lower laser energy with lower frequency leads to the formation of smaller permalloy nanoparticles. Higher concentration of SDS results in smaller nanoparticles. Lastly, we found some unusual permalloy nanoparticles with interesting morphologies made by PLA in air, distilled water and ethanol.

scholarly journals The structure of surface films. Part XVII.—γ hydroxy-stearic acid and its lactone

1933 ◽  
Vol 140 (840) ◽  
pp. 223-226 ◽  
Keyword(s):  
Stearic Acid ◽  
Aqueous Solutions ◽  
Surface Pressure ◽  
Surface Films ◽  
Hydroxy Stearic Acid ◽  
Monomolecular Films ◽  
Made In

This paper describes observations, mostly made in 1924 and not hitherto published in detail,* on the surface pressure of γ hydroxy-stearic acid (I) and its lactone (II) spread as monomolecular films on aqueous solutions. CH3 3 CH3 3 (CH 2 ) 13 (CH 2 ) 13 CHOH CH CH 2 CH 2 CH 2 O COOH CH 2 – CO I II Most of the measurements were made with the modification of Langmuir’s apparatus described in Parts I and II of this series of papers,† in which jets of air prevent the film passing the ends of the float. A few confirmatory observations have been made since, with the apparatus of Adam and Jessop, in which thin metallic ribbons block these gaps. The acid and lactone were kindly given me by Dr. P. W. Clutterbuck, of Manchester University.

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