scholarly journals Ligand-Assisted Growth of Nanowires from Solution

2021 ◽  
Vol 11 (16) ◽  
pp. 7641
Author(s):  
Victor M. Burlakov ◽  
Alain Goriely
Keyword(s):  
Statistical Mechanics ◽  
Interaction Energy ◽  
Growth Process ◽  
Crystal Shape ◽  
Growth Processes ◽  
Crystal Facet ◽  
Anisotropic Nanomaterials

We consider the development of ligand-assisted growth processes for generating shape-anisotropic nanomaterials. Using statistical mechanics, we analyze the conditions under which ligand-assisted growth of shape-anisotropic crystalline nanomaterials from solution can take place. Depending on ligand-facet interaction energy and crystal facet area, molecular ligands can form compact layers on some facets leaving other facets free. The growth process is then restricted to free facets and may result in significant anisotropy in crystal shape. Our study uncovers the conditions for ligand-assisted growth of nanoplatelets and nanowires from isotropic or anisotropic seed nanocrystals of cuboid shape. We show that in contrast to nanoplatelets, ligand-assisted growth of nanowires requires certain anisotropy in the ligand-facet interaction energy.

scholarly journals In-situ HRTEM observations of growth process of decagonal quasicrystals

2014 ◽  
Vol 70 (a1) ◽  
pp. C97-C97
Author(s):  
Keisuke Nagao ◽  
Kazue Nishimoto ◽  
Tomoaki Inuduka ◽  
Keiichi Edagawa
Keyword(s):  
Growth Mechanism ◽  
Growth Process ◽  
Structural Information ◽  
Growth Models ◽  
Experimental Studies ◽  
Unit Cell ◽  
Small Scale ◽  
Growth Processes ◽  
Decagonal Quasicrystals

Quasicrystals possess quasiperiodicity, where the structure cannot be described simply by the repetition of unit cell like conventional crystals. This fact raises the question of how quasicrystals grow, i.e., what physical mechanism makes the growth of quasicrystals possible. While crystals can grow by copying a unit cell via local atomic interactions, nonlocal structural information seems to be required in the growth of quasicrystals. This problem has attracted much attention ever since the first discovery of a quasicrystal in 1984, and several theoretical growth models [1] have been proposed. However, no experimental studies have so far been reported, and it is still unclear whether these theoretical growth models apply to real quasicrystals. In the present study, we have conducted in-situ high-temperature electron microscopic (HRTEM: High-Resolution Transmission Electron Microscopy) observations of the growth process of decagonal quasicrystals to elucidate the growth mechanism. The growth processes of a decagonal quasicrystal of Al70.8Ni19.7Co9.5were observed by HRTEM in the temperature range 1073-1173K. Tiling patterns with edge length of about 2nm were constructed from a series of HRTEM images. They were analysed in the framework of the projection method. Here, we followed the procedures in our previous work [2]. We have already reported the results of some observations and analyses elsewhere [3]. However, the growth processes of them were on a small scale, and the results were indefinite. Recently, we have succeeded in observing a growth process on a massive scale. In this paper, we present the results of this observation and subsequent analyses, and discuss the growth mechanism of the quasicrystal.

Novel Molten Salt Assisted Autocombustion Method for the Synthesis of Aluminum-Doped SrFe12−xAlxO19 Hexaferrite Nanoparticles

2020 ◽  
Vol 20 (12) ◽  
pp. 7735-7742
Author(s):  
T. P. Poudel ◽  
D. Guragain ◽  
J. Mohapatra ◽  
J. P. Liu ◽  
S. R. Mishra
Keyword(s):  
Magnetic Properties ◽  
Molten Salt ◽  
Grain Growth ◽  
Growth Process ◽  
High Coercivity ◽  
Crystal Shape ◽  
Squareness Ratio ◽  
Highly Dispersed ◽  
Novel Method ◽  
Shape And Size

The study presents a novel molten salt assisted autocombustion synthesis of SrFe12−xAlxO19 particles. The extrinsic magnetic properties such as coercivity and the remanence of sintered M-type ferrites are highly dependent on the microstructure viz. morphology and size, of the ferrite particles. The control of the microstructures of ferrite particles is usually achieved via control nucleation and grain growth process. In this study, NaCl salt was used to control the crystal shape and size of Al3+ doped SrFe12−xAlxO19 particles. The presented novel method couples advantage of deriving homogenized particles via auctocombustion first and later sintering in the presence of NaCl salt. Highly dispersed, homogeneous, and hexagonal shaped SrFe12−xAlxO19 ferrite particles were achieved with this method. The particles derived via the molten salt assisted method presented a high coercivity and squareness ratio (>0.5) as compared to that obtained via autocombustion method only.

A Method for Estimating Treatment Effects When Individuals are Growing

1980 ◽  
Vol 5 (1) ◽  
pp. 5-34 ◽  
Author(s):  
Anthony S. Bryk ◽  
Judith F. Strenio ◽  
Herbert I. Weisberg
Keyword(s):  
Data Analysis ◽  
Present Article ◽  
Growth Process ◽  
Value Added ◽  
Estimation Procedure ◽  
Educational Programs ◽  
Natural Growth ◽  
Analytic Model ◽  
Growth Processes ◽  
Program Impact

In an earlier paper (Bryk & Weisberg, 1976) , we introduced the value-added analysis. This approach built on the notion that many educational programs are dynamic interventions in natural growth processes. In particular, by modeling the natural growth process, we developed an analytic model and estimation procedure for assessing program impact on these growth processes. The present article extends the theory and applications of value-added analysis in several important directions. We present here for practitioners and researchers a coherent overview of the method that emphasizes intuitive rationale and simple data analysis procedures.

The dynamics of SME growth processes and the role of enabling constraints: an evidence-based theoretical framework

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Marta Gancarczyk ◽  
Joerg Freiling ◽  
Jacek Gancarczyk
Keyword(s):  
Growth Process ◽  
High Growth ◽  
Case Study Method ◽  
Growth Processes ◽  
Content Type ◽  
Theoretical Contribution ◽  
Multiple Case

PurposeThis paper aims to explain the dynamics of entrepreneurial decisions and actions (D&As) in the small and medium-sized enterprise (SME) growth process. The study focuses on the changing portfolio and relationship governance and captures these dynamics by using the concept of “enabling constraints” (ECs).Design/methodology/approachIn-depth, long-term and multiple-case study method was adopted based on six high-growth SMEs. Pattern-matching and alternative template approach formed a basis for developing a research framework, further corroborated and advanced in the empirical study.FindingsThe research provides empirical evidence of ECs as entrepreneurial perceptions that both limit (constrain) the range of accessible options and facilitate (enable) new opportunities. This study’s results point to how owner-managers' judgments about growth motives and rationales constrain their choices and how they enable new directions, acknowledging the changing context.Originality/valueThis work contributes to the research on SME growth processes by specifying their dynamics in terms of a creative mutual causality. Here, D&As stem from entrepreneurs' perceptions that are affected by the context, with the latter also shaped by prior decisions and actions. This theoretical contribution has been synthesized in the form of a framework of ECs in the SME growth process with related propositions.

Synthesis of R2 Fe14 B Single Crystals

1987 ◽  
Vol 96 ◽  
Author(s):  
B. N. Das ◽  
N. C. Koon
Keyword(s):  
Rare Earth ◽  
Crystal Growth ◽  
Single Crystals ◽  
Growth Process ◽  
Alloy Composition ◽  
Crystal Quality ◽  
Solidification Microstructure ◽  
Growth Processes ◽  
Crystal Growth Process ◽  
Isomorphous Replacement

ABSTRACTSingle crystals of R2 Fe14 B weighing 5 to 15 g were grown from a liquid melt by tri-arc and levitation Czochralski methods. The arc method was used for the growth of smaller size crystals from 5 to 7 g, and the levitation method was used for the growth of larger sizes, from 10 to 15 g. Crystals of (R1)2 –x(R2)xFe14 B could also be grown with isomorphous replacement of rare earth atoms. The starting alloy composition for the crystal growth process was chosen based on solidification microstructure. In this paper we discuss the solidification microstructure, isomorphous replacement, seeding and their interactions with the crystal growth processes and crystal quality.

scholarly journals EQUILIBRIUM STATISTICAL MECHANICS OF FERMION LATTICE SYSTEMS

2003 ◽  
Vol 15 (02) ◽  
pp. 93-198 ◽  
Author(s):  
HUZIHIRO ARAKI ◽  
HAJIME MORIYA
Keyword(s):  
Statistical Mechanics ◽  
Interaction Energy ◽  
Convergence Condition ◽  
Point Interaction ◽  
Translation Invariance ◽  
Major Result ◽  
Lattice Systems ◽  
Equilibrium Statistical Mechanics ◽  
Spin Lattice ◽  
The One

We study equilibrium statistical mechanics of Fermion lattice systems which require a different treatment compared with spin lattice systems due to the non-commutativity of local algebras for disjoint regions. Our major result is the equivalence of the KMS condition and the variational principle with a minimal assumption for the dynamics and without any explicit assumption on the potential. Its proof applies to spin lattice systems as well, yielding a vast improvement over known results. All formulations are in terms of a C*-dynamical systems for the Fermion (CAR) algebra [Formula: see text] with all or a part of the following assumptions: (I) The interaction is even, namely, the dynamics αt commutes with the even-oddness automorphism Θ. (Automatically satisfied when (IV) is assumed.) (II) The domain of the generator δα of αt contains the set [Formula: see text] of all strictly local elements of [Formula: see text]. (III) The set [Formula: see text] is the core of δα. (IV) The dynamics αt commutes with lattice translation automorphism group τ of [Formula: see text]. A major technical tool is the conditional expectation from [Formula: see text] onto its C*-subalgebras [Formula: see text] for any subset I of the lattice, which induces a system of commuting squares. This technique overcomes the lack of tensor product structures for Fermion systems and even simplifies many known arguments for spin lattice systems. In particular, this tool is used for obtaining the isomorphism between the real vector space of all *-derivations with their domain [Formula: see text], commuting with Θ, and that of all Θ-even standard potentials which satisfy a specific norm convergence condition for the one point interaction energy. This makes it possible to associate a unique standard potential to every dynamics satisfying (I) and (II). The convergence condition for the potential is a consequence of its definition in terms of the *-derivation and not an additional assumption. If translation invariance is imposed on *-derivations and potentials, then the isomorphism is kept and the space of translation covariant standard potentials becomes a separable Banach space with respect to the norm of the one point interaction energy. This is a crucial basis for an application of convex analysis to the equivalence proof in the major result. Everything goes in parallel for spin lattice systems without the evenness assumption (I).

scholarly journals Aerosol Impacts on the Microphysical Growth Processes of Orographic Snowfall

2013 ◽  
Vol 52 (4) ◽  
pp. 834-852 ◽  
Author(s):  
Stephen M. Saleeby ◽  
William R. Cotton ◽  
Douglas Lowenthal ◽  
Joe Messina
Keyword(s):  
Growth Process ◽  
Spillover Effect ◽  
Supercooled Liquid ◽  
Atmospheric Modeling ◽  
Regional Atmospheric Modeling System ◽  
Growth Processes ◽  
Cloud Droplets ◽  
Microphysical Processes ◽  
Orographic Cloud ◽  
Regional Atmospheric Modeling

AbstractThe Regional Atmospheric Modeling System was used to simulate four winter snowfall events over the Park Range of Colorado. For each event, three hygroscopic aerosol sensitivity simulations were performed with initial aerosol profiles representing clean, moderately polluted, and highly polluted scenarios. Previous work demonstrates that the addition of aerosols can produce a snowfall spillover effect, during events in which riming growth of snow is prevalent in the presence of supercooled liquid water, that is due to a modified orographic cloud containing more numerous but smaller cloud droplets. This study focuses on the detailed microphysical processes that lead to snow growth in each event and how these processes are modulated by the addition of hygroscopic aerosols. A conceptual model of hydrometeor growth processes is presented, along a vertical orographic transect, that reveals zones of vapor deposition of ice and liquid, riming growth, evaporation, sublimation, and regions in which the Wegener–Bergeron–Findeisen (WBF) snow growth process is active. While the aerosol-induced spillover effect is largely determined by the degree of reduction in ice particle riming, an enhancement in the WBF snow growth process under more polluted conditions largely offsets the loss of rime growth, thus leading to a minimal net change in the regional precipitation.

Effect of power arrangement on the crystal shape during the Kyropoulos sapphire crystal growth process

2012 ◽  
Vol 352 (1) ◽  
pp. 9-15 ◽  
Author(s):  
Chun-Hung Chen ◽  
Jyh-Chen Chen ◽  
Chung-Wei Lu ◽  
Che-Ming Liu
Keyword(s):  
Crystal Growth ◽  
Growth Process ◽  
Sapphire Crystal ◽  
Crystal Shape ◽  
Crystal Growth Process

Random growth in a tessellation

1973 ◽  
Vol 74 (3) ◽  
pp. 515-528 ◽  
Author(s):  
Daniel Richardson
Keyword(s):  
Euclidean Space ◽  
Growth Process ◽  
Dimensional Euclidean Space ◽  
Growth Processes ◽  
Stochastic Growth ◽  
Random Growth

Let S be n dimensional Euclidean space and let T be a division of S into cells. Assume that each cell must be either white or black at any time t. At time 0 the cell at the origin, α0, is black and all other cells are white. Let G be some stochastic growth process which tends to change white cells with black neighbours into black cells. Let C(t) be the black shape at time t. For a family, F, of such growth processes we prove the following theorem.

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