Dynamics of Silicon Nanoparticle Synthesis by Pulsed Laser Ablation

2005 ◽  
Vol 879 ◽  
Author(s):  
P.T. Murray ◽  
L. Grazulis
Keyword(s):  
Size Distribution ◽  
Nanoparticle Synthesis ◽  
Flight Mass Spectrometry ◽  
Peak Broadening ◽  
Si Nanoparticles ◽  
Multiple Ionization ◽  
Ar Gas ◽  
Log Normal ◽  
Log Normal Distribution ◽  
Nanoparticle Sizes

AbstractSi nanoparticles have been synthesized by ablating a Si target in Ar with 355 nm laser radiation. The nanoparticle size distribution has been determined in real time by laser-induced time of flight mass spectrometry. Under these conditions, nanoparticles that are formed in 1.0 and 2.0 Torr of background Ar gas exhibit log-normal size distributions with most probable diameters of 2.6 and 3.0 nm, respectively. The speed distribution of the nanoparticles has been determined by varying the time delay between the ablation and photoionization lasers. The results indicate that the most probable speed of the nanoparticles, after formation and a 25 mm drift in background Ar, is 100 m/s. Finally, there is a deviation of the size distribution from the log-normal distribution at small nanoparticle sizes. This is attributed to multiple ionization of the nanoparticles. Confirming evidence for multiple ionization is provided by the atomic and mass spectra which show peak broadening due to Coulomb explosion.

Coarsening of MX Nitrides in Cr-Mo-N-X(X=V,Nb,Ti) Ferritic Steels

2007 ◽  
Vol 124-126 ◽  
pp. 1661-1664
Author(s):  
Deuck Seung Bae ◽  
Woo Sang Jung ◽  
Suk Woo Hong ◽  
Sang Min Song ◽  
Soon Hyo Chung ◽  
...  
Keyword(s):  
Size Distribution ◽  
Stainless Steels ◽  
Austenitic Stainless Steels ◽  
Ferritic Steels ◽  
Reactor Irradiation ◽  
First Wall ◽  
Fusion Power ◽  
Log Normal ◽  
Log Normal Distribution ◽  
Oswald Ripening

Ferritic steels have been candidate structural materials for first wall and blanket structures of fusion power plant since the late 1970’s, when the fast-reactor irradiation showed them to be more swelling resistant than austenitic stainless steels. In this investigation, the coarsening of MX nitrides during aging was studied for Cr-Mo-N-X(X=V, Nb, Ti) ferritic steels. During the aging, (V, Nb, Ti)nitrides were precipitated out. From TEM observation, particle size distribution was confirmed and size distribution follows a typical log-normal distribution. The coarsening rate of MX nitrides was correlated with the Oswald ripening equation.

Precipitation Behavior of MX Phase in Cr-Mo-N-X(X=V,Nb,Ti) Ferritic Steels

2007 ◽  
Vol 345-346 ◽  
pp. 1553-1556
Author(s):  
Deuck Seung Bae ◽  
Woo Sang Jung ◽  
Kyung Tae Hong ◽  
Kyung Sub Lee
Keyword(s):  
Size Distribution ◽  
Creep Strength ◽  
Strengthening Mechanism ◽  
Ferritic Steels ◽  
Precipitation Behavior ◽  
Coarsening Behavior ◽  
Steel Increase ◽  
The Matrix ◽  
Log Normal ◽  
Log Normal Distribution

The precipitation behavior of MX nitrides during aging was investigated for Cr-Mo-N-X (X=V,Nb,Ti) ferritic steels. MX nitrides, which are finely dispersed in the matrix of Cr-Mo ferritic heat resistance steel, increase the creep strength of the steels by the precipitation strengthening mechanism. However, MX particles usually coarsen during aging, and this results in a decrease of creep strength. In order to clarify the coarsening process of MX particles, TEM samples were prepared from the aged for up to 3000hours specimens. During the aging, V, Nb and Ti containing nitrides (called MX nitrides) were precipitated out. From TEM observation, particle size distribution was confirmed and size distribution follows a typical log-normal distribution. The observed coarsening behavior well agreed with the calculated coarsening behavior of precipitates by Oswald ripening equation.

scholarly journals On the dynamics of farm size distribution in Finland

1975 ◽  
Vol 47 (6) ◽  
pp. 454-461
Author(s):  
Devendra Sahal
Keyword(s):  
Normal Distribution ◽  
Size Distribution ◽  
Farm Size ◽  
Time Period ◽  
Farm Structure ◽  
Log Normal ◽  
Log Normal Distribution

This study attempts to explain why farm structure in Finland is what it is. The static aspects of size distribution are summarised by means of log-normal distribution and tested with respect to data on more than 500 communes for years 1959 and 1969. As to the dynamic aspects, despite some correlation between percentage growth and size at the beginning of the time period and which is believed to be partly spurious, the observed phenomena do not seem to be incompatible with the proposed version of law of proportionate effect. The latter need not be observed at every point in time.

scholarly journals Peculiarities of data processing for optical measurements of disperse parameters of bimodal media

2019 ◽  
Vol 43 (4) ◽  
pp. 692-698 ◽  
Author(s):  
A.A. Zhirnov ◽  
O.B. Kudrjashova
Keyword(s):  
Experimental Data ◽  
Particle Size ◽  
Distribution Function ◽  
Particulate Matter ◽  
Particle Size Distribution ◽  
Normal Distribution ◽  
Size Distribution ◽  
A Priori ◽  
Log Normal ◽  
Log Normal Distribution

This study is focused on enhancing the informativity of optical measurement techniques for particulate matter. The problem is that the description of particulate matter with bimodal and multimodal distributions by an a priori defined analytical function of particle size distribution (for example, a log-normal distribution) is not accurate enough. Here, we explore if experimental data can be approximated by a multivariable function of particle size distribution instead of using the a priori defined log-normal distribution. For the comparison of the approximation results, experiments are conducted on standard samples with granulometric compositions OGS-01LM and OGS-08LM separately and jointly in a mix. The experimental data are recorded by a high-selectivity turbidimetric technique in water suspensions of these samples. The purpose of this study is to present the measurement results as a distribution function that enables one to identify more accurately the particle-size distribution profile and the corresponding disperse characteristics of the aerosol in question when measuring parameters of disperse media by optical techniques. The main objective of this work is to develop, implement and verify a search algorithm for the particle-size distribution function by way of a multi-parameter function. We show that the solution to the problem proposed herein is more universal because it allows slow and fast processes in suspensions and aerosols to be examined with a lower error. The algorithm can be applied to the problems which are based on solving first-kind Fredholm equations.

A Study of Guinier-Preston Zone Growth Kinetics Through the Use of X-Ray Small-Angle Scattering*

1968 ◽  
Vol 12 ◽  
pp. 97-112 ◽  
Author(s):  
Samuel D. Harkness ◽  
Robert W. Gould
Keyword(s):  
Size Distribution ◽  
Small Angle ◽  
Small Angle Scattering ◽  
Miscibility Gap ◽  
X Ray ◽  
Transmission Electron ◽  
Angle Scattering ◽  
Log Normal ◽  
Log Normal Distribution ◽  
Zone Growth

AbstractThe relation of the X-ray small-angle scattering parameters to the results of transmission electron microscopy for spherical Guinier-Preston zones was investigated. Experimentally, the Guinier radius is found to equal (<R7>/<R5>1/2) and the Porod radius to equal <R3>/<R2>. These results were theoretically predicted by Baur and Gerold, A log normal distribution was found to be in close agreement with the experimental data. The use of this distribution allowed the size-distribution curve of spherical Guinier-Preston zones to be constructed from the X-ray parameters and from a knowledge of the metastable miscibility gap. This approach is used to follow the evolution of size distribution in both Al-Ag and Al-Zn alloys. The application of this approach to nncleation and growth as well as redistribution processes is discussed. Growth paths are established from the size distribution evolution curves through an Nv> construction. A brief discussion of the technique is included.

scholarly journals Grain-Size Distribution Effects on the Attenuation of Laser-Generated Ultrasound in α-Titanium Alloy

Materials ◽  
2018 ◽  
Vol 12 (1) ◽  
pp. 102 ◽  
Author(s):  
Xue Bai ◽  
Yang Zhao ◽  
Jian Ma ◽  
Yunxi Liu ◽  
Qiwu Wang
Keyword(s):  
Grain Size ◽  
Titanium Alloy ◽  
Normal Distribution ◽  
Size Distribution ◽  
Grain Size Distribution ◽  
Fourth Power ◽  
Grain Sizes ◽  
Mean Grain Size ◽  
Log Normal ◽  
Log Normal Distribution

Average grain size is usually used to describe a polycrystalline medium; however, many investigations demonstrate the grain-size distribution has a measurable effect on most of mechanical properties. This paper addresses the experimental quantification for the effects of grain-size distribution on attenuation in α-titanium alloy by laser ultrasonics. Microstructures with different mean grain sizes of 26–49 μm are obtained via annealing at 800 °C for different holding times, having an approximately log-normal distribution of grain sizes. Experimental measurements were examined by using two different theoretical models: (i) the classical Rokhlin’s model considering a single mean grain size, and (ii) the improved Turner’s model incorporating a log-normal distribution of grain sizes in the attenuation evaluation. Quantitative agreement between the experiment and the latter model was found in the Rayleigh and the Rayleigh-to-stochastic transition regions. A larger attenuation level was exhibited than the classical theoretical prediction considering a single mean grain size, and the frequency dependence of attenuation reduced from a classical fourth power to an approximately second power due to a greater probability of large grains than the assumed Poisson statistics. The provided results would help support the use of laser ultrasound technology for the non-destructive evaluation of grain size distribution in polycrystalline materials.

Determination of particle size distribution in an Fe2O3-based catalyst using magnetometry and x-ray diffraction

1992 ◽  
Vol 7 (7) ◽  
pp. 1856-1860 ◽  
Author(s):  
Manjula M. Ibrahim ◽  
Jianmin Zhao ◽  
Mohindar S. Seehra
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Line Broadening ◽  
X Ray Diffraction ◽  
X Ray ◽  
Mössbauer Measurements ◽  
Log Normal ◽  
Log Normal Distribution

In this paper, the techniques of SQUID magnetometry and line broadening in x-ray diffraction are employed for determining an important parameter for catalysts, viz. the particle size distribution. Magnetization versus temperature (5 K–400 K) and magnetization versus field (up to 55 kOe) data are reported for an α–Fe2O3 based catalyst. After determining the region of superparamagnetism, the distribution function f(r) is determined assuming a log normal distribution and Langevin paramagnetism of superparamagnetic particles. The distribution is found to be fairly symmetric with center near 65 Å and range of 35 to 115 Å. From line-broadening of Bragg peaks in x-ray diffraction, particle radii varying between 75 Å and 110 Å are obtained. These results are compared with the reported Mössbauer measurements of Huffman et al. on the same sample.

scholarly journals A Universal Model for the Log-Normal Distribution of Elasticity in Polymeric Gels and Its Relevance to Mechanical Signature of Biological Tissues

Biology ◽  
2021 ◽  
Vol 10 (1) ◽  
pp. 64
Author(s):  
Arnaud Millet
Keyword(s):  
Elastic Modulus ◽  
Normal Distribution ◽  
Biological Tissues ◽  
Force Microscopy ◽  
Polymeric Gels ◽  
Atomic Force ◽  
Clear Explanation ◽  
Log Normal ◽  
Log Normal Distribution

The mechanosensitivity of cells has recently been identified as a process that could greatly influence a cell’s fate. To understand the interaction between cells and their surrounding extracellular matrix, the characterization of the mechanical properties of natural polymeric gels is needed. Atomic force microscopy (AFM) is one of the leading tools used to characterize mechanically biological tissues. It appears that the elasticity (elastic modulus) values obtained by AFM presents a log-normal distribution. Despite its ubiquity, the log-normal distribution concerning the elastic modulus of biological tissues does not have a clear explanation. In this paper, we propose a physical mechanism based on the weak universality of critical exponents in the percolation process leading to gelation. Following this, we discuss the relevance of this model for mechanical signatures of biological tissues.

scholarly journals Extreme geomagnetic activities: a statistical study

2020 ◽  
Vol 72 (1) ◽  
Author(s):  
Ryuho Kataoka
Keyword(s):  
Magnetic Storms ◽  
Magnetic Observatory ◽  
Statistical Distributions ◽  
Limited Data ◽  
Data Set ◽  
Sudden Commencements ◽  
The One ◽  
Log Normal ◽  
Geomagnetic Activities ◽  
Log Normal Distribution

Abstract Statistical distributions are investigated for magnetic storms, sudden commencements (SCs), and substorms to identify the possible amplitude of the one in 100-year and 1000-year events from a limited data set of less than 100 years. The lists of magnetic storms and SCs are provided from Kakioka Magnetic Observatory, while the lists of substorms are obtained from SuperMAG. It is found that majorities of events essentially follow the log-normal distribution, as expected from the random output from a complex system. However, it is uncertain that large-amplitude events follow the same log-normal distributions, and rather follow the power-law distributions. Based on the statistical distributions, the probable amplitudes of the 100-year (1000-year) events can be estimated for magnetic storms, SCs, and substorms as approximately 750 nT (1100 nT), 230 nT (450 nT), and 5000 nT (6200 nT), respectively. The possible origin to cause the statistical distributions is also discussed, consulting the other space weather phenomena such as solar flares, coronal mass ejections, and solar energetic particles.

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