Thermodynamic model of crystallization and melting of small particles

Open Physics ◽  
2004 ◽  
Vol 2 (1) ◽  
Author(s):  
Vladimir Samsonov ◽  
Oleg Malkov
Keyword(s):  
Melting Temperature ◽  
Thermodynamic Model ◽  
Size Dependence ◽  
Nonequilibrium Thermodynamics ◽  
Spherical Particles ◽  
Small Particles ◽  
Crystal Nucleus

AbstractThe size dependence of the nanocrystal melting temperature has been investigated based on a nonequilibrium thermodynamics approach. An expression has been derived for the melting temperature that, contrary to the classical Tomson formula, takes into account the metastable character of the crystal nucleus-melt shell equilibrium. Quantitative estimations have been carried out for small spherical particles of aluminum, tin, and lead.

STEM Study of Surface Plasmon Excitation in Small Spherical Particles

1990 ◽  
Vol 48 (2) ◽  
pp. 42-43
Author(s):  
Daniel UGARTE
Keyword(s):  
Energy Loss ◽  
Spherical Particles ◽  
Small Particles ◽  
Bulk Materials ◽  
Low Loss ◽  
Plasmon Excitation ◽  
Surface Modes ◽  
Surface Plasmon Excitation ◽  
Analytical Electron ◽  
Analytical Electron Microscope

Small particles exhibit chemical and physical behaviors substantially different from bulk materials. This is due to the fact that boundary conditions can induce specific constraints on the observed properties. As an example, energy loss experiments carried out in an analytical electron microscope, constitute a powerful technique to investigate the excitation of collective surface modes (plasmons), which are modified in a limited size medium. In this work a STEM VG HB501 has been used to study the low energy loss spectrum (1-40 eV) of silicon spherical particles [1], and the spatial localization of the different modes has been analyzed through digitally acquired energy filtered images. This material and its oxides have been extensively studied and are very well characterized, because of their applications in microelectronics. These particles are thus ideal objects to test the validity of theories developed up to now.Typical EELS spectra in the low loss region are shown in fig. 2 and energy filtered images for the main spectral features in fig. 3.

scholarly journals The Formation of Deposits on the Walls of the Pores in the Filtering Process

2019 ◽  
Vol 14 (2) ◽  
pp. 15-22
Author(s):  
Yu. A. Taran ◽  
A. V. Kozlov ◽  
A. L. Taran
Keyword(s):  
Experimental Data ◽  
Pressure Drop ◽  
Driving Force ◽  
Nonequilibrium Thermodynamics ◽  
Driving Forces ◽  
Solid Particles ◽  
Original Structure ◽  
Small Particles ◽  
Filtration Process ◽  
Filter Unit

The aim of the work is to consider the mechanism of clogging the pores of the filter unit by small particles from the flow of filtrate inside them. Theoretical ideas about the process of filtering with the deposition of small particles from the filtrate on the pore walls and attribution of its fundamentals to restructuring from the original structure to the final structure allow to describe the process of clogging the pores using well studied concepts of known processes with phase transformations (in particular, crystallization). Based on this analogy and the approach to the description of the transformation of the "old" structure into a "new" one in time, using experimental data and their processing we calculated the rate of nucleation of the sediment centers (ωnucl), the linear (υlin) and volumetric rates of sediment plaques growth in the pores of the filter unit at different values of the process driving force, at different pressure difference in the system, and at different concentrations of solid particles in the suspension. Interpolation and extrapolation dependences were obtained for analyzing the mechanisms of sediments formation and growth for determining and calculating these (ωnucl, υlin) rates. Using the concepts of nonequilibrium thermodynamics to assess the influence of the driving forces we studied their influence (changes in the concentration of solid particles in the filtrate suspension and pressure drop across the filtering layer) on the dynamics of the filtration process. Using the data obtained it is possible to find the degree of clogging of through pores, which determines the filtration conditions, the filter septum type, and the filter overall dimensions.

EXAFS STUDY ON THE NONCRYSTALLINE STRUCTURE OF BINARY COMPONENT (BiCu, BiTe) NANOPHASE PARTICLES

1996 ◽  
Vol 03 (01) ◽  
pp. 71-74 ◽  
Author(s):  
M. ITOH ◽  
S. TOHNO ◽  
M. ADACHI ◽  
K. KIMURA
Keyword(s):  
Melting Point ◽  
Line Shape ◽  
Size Dependence ◽  
Thermal Fluctuation ◽  
Exafs Spectrum ◽  
Small Particles ◽  
Bulk Materials ◽  
Soft Surface ◽  
Exafs Study ◽  
Specific Line

From the viewpoint of the size dependence of the melting point of small particles, the microstructure of nanophase particles is investigated with EXAFS. Two EXAFS spectrum from BiCu and BiTe nanophase particles indicated the specific line shape due to the disorder of atomic structure of the particles, which was not found for corresponding bulk materials. This fact means that a nanophase particle has not only soft surface due to size effect but also a liquid-like inner structure caused by a thermal fluctuation.

INTERMITTENCY ANALYSIS OF FRAGMENTING NUCLEI WITH EXACT CONSERVATION LAWS

1993 ◽  
Vol 08 (07) ◽  
pp. 1283-1294
Author(s):  
K. HAGLIN ◽  
C. GALE ◽  
S. DAS GUPTA
Keyword(s):  
Monte Carlo ◽  
Conservation Laws ◽  
Thermodynamic Model ◽  
Nuclear Emulsion ◽  
Size Dependence ◽  
Conserved Quantities ◽  
Factorial Moments ◽  
Evaporation Model ◽  
Scaled Factorial Moments ◽  
Intermittency Analysis

We show that the speculative charge bin size dependence of the scaled factorial moments for fragmenting nuclei in recent nuclear emulsion data may be attributed in part to simple conservation laws. Monte Carlo results from both the Thermodynamic Model and an Evaporation Model suggest that in such studies most or all of the effect is due to the fact that there exist constraints owing to conserved quantities.

A direct numerical investigation of two-way interactions in a particle-laden turbulent channel flow

2019 ◽  
Vol 875 ◽  
pp. 1096-1144 ◽  
Author(s):  
Cheng Peng ◽  
Orlando M. Ayala ◽  
Lian-Ping Wang
Keyword(s):  
Channel Flow ◽  
Finite Size ◽  
Turbulent Channel Flow ◽  
Spherical Particles ◽  
Homogeneous Distribution ◽  
Particle Sizes ◽  
Small Particles ◽  
Particle Rotation ◽  
Turbulence Modulation ◽  
Budget Analysis

Understanding the two-way interactions between finite-size solid particles and a wall-bounded turbulent flow is crucial in a variety of natural and engineering applications. Previous experimental measurements and particle-resolved direct numerical simulations revealed some interesting phenomena related to particle distribution and turbulence modulation, but their in-depth analyses are largely missing. In this study, turbulent channel flows laden with neutrally buoyant finite-size spherical particles are simulated using the lattice Boltzmann method. Two particle sizes are considered, with diameters equal to 14.45 and 28.9 wall units. To understand the roles played by the particle rotation, two additional simulations with the same particle sizes but no particle rotation are also presented for comparison. Particles of both sizes are found to form clusters. Under the Stokes lubrication corrections, small particles are found to have a stronger preference to form clusters, and their clusters orientate more in the streamwise direction. As a result, small particles reduce the mean flow velocity less than large particles. Particles are also found to result in a more homogeneous distribution of turbulent kinetic energy (TKE) in the wall-normal direction, as well as a more isotropic distribution of TKE among different spatial directions. To understand these turbulence modulation phenomena, we analyse in detail the total and component-wise volume-averaged budget equations of TKE with the simulation data. This budget analysis reveals several mechanisms through which the particles modulate local and global TKE in the particle-laden turbulent channel flow.

The melting temperature of nanorods: diameter and length dependences

2020 ◽  
Vol 22 (25) ◽  
pp. 14210-14215 ◽  
Author(s):  
Zhengming Zhang ◽  
Xianshang Meng ◽  
Haiming Lu ◽  
Ming Li
Keyword(s):  
Melting Temperature ◽  
Thermodynamic Model

An analytical thermodynamic model was developed to describe the effect of diameter and length on the melting temperature of nanorods.

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