scholarly journals Microscopic and Surface Properties of K-Na Liquid Alloys

2013 ◽  
Vol 4 ◽  
pp. 40-45
Author(s):  
I. Koirala ◽  
B. P. Singh ◽  
I. S. Jha
Keyword(s):  
Surface Properties ◽  
Order Parameter ◽  
Short Range ◽  
Short Range Order ◽  
Energy Parameter ◽  
Surface Concentration ◽  
Liquid Alloys ◽  
Range Order Parameter ◽  
Temperature Dependent ◽  
Long Wavelength

The deviation from ideal mixture behavior and concentration dependent symmetry in the microscopic and surface properties of K-Na liquid alloy is investigated within a simple statistical model. The concentration dependent of microscopic functions(concentration fluctuation in the long wavelength limit, Warren-Cowley short range order parameter) and surface properties(surface concentration and surface tension) has got special attention to show a tendency of like atom pairing in the mixture. The theoretical analysis reveals that energy parameter is temperature dependent, K-Na alloys is of weakly interacting system and K-atoms segregates on the surface of K-Na liquid alloys at bulk concentration of Na.The Himalayan Physics Vol. 4, No. 4, 2013 Page: 40-45 Uploaded date: 12/23/2013 

Quasi-Chemical Model for Liquid Li-Cd Alloys

1989 ◽  
Vol 44 (6) ◽  
pp. 529-532
Author(s):  
L. C. Prasad ◽  
R. N. Singh
Keyword(s):  
Order Parameter ◽  
Short Range ◽  
Short Range Order ◽  
Chemical Model ◽  
Liquid Alloys ◽  
Range Order Parameter ◽  
Long Wavelength ◽  
Pairwise Interactions ◽  
Energy Of Mixing ◽  
Free Energy Of Mixing

The quasi-chemical model based on pairwise interactions is used to study the concentration dependent thermodynamic properties of Li-Cd liquid alloys. Special attention is given to the concentration-concentration correlation function in the long wavelength limit [Scc(0)] and the chemical short-range order parameter (CSRO). The activity, free energy of mixing, Scc(0) and CSRO are computed as functions of temperature and concentration.

scholarly journals Structural study of liquid Sn-Tl alloys

BIBECHANA ◽  
2014 ◽  
Vol 11 ◽  
pp. 46-52
Author(s):  
RP Koirala ◽  
IS Jha ◽  
BP Singh ◽  
D Adhikari
Keyword(s):  
Order Parameter ◽  
Short Range ◽  
Short Range Order ◽  
Theoretical Models ◽  
Temperature Dependent ◽  
Long Wavelength ◽  
Energy Interaction ◽  
Energy Of Mixing ◽  
Free Energy Of Mixing ◽  
The Comparative Study

The concentration fluctuations in long wavelength limit, Scc(0) and the Warren-Cowley short range order parameter (α1) are important microscopic functions which provide valuable information about the local arrangements of the constituent atoms in the alloy melts. In order to investigate the nature of atomic ordering in Sn-Tl alloy in the molten state at 723K, we have computed these functions using theoretical models. The models satisfactorily explain the small asymmetry observed in the experimental data of free energy of mixing of the alloy. The comparative study further reveals that the energy interaction parameters are temperature dependent and the Sn-Tl alloy is weakly interacting segregating system. DOI: http://dx.doi.org/10.3126/bibechana.v11i0.10379   BIBECHANA 11(1) (2014) 46-52

Pb()O3-type Perovskites: Part I. Pair-correlation Theory of Order-disorder Phase Transition

1997 ◽  
Vol 12 (8) ◽  
pp. 2117-2126 ◽  
Author(s):  
Hyun M. Jang ◽  
Su-Chan Kim
Keyword(s):  
Long Range ◽  
Order Parameter ◽  
Short Range ◽  
Short Range Order ◽  
Pair Correlation ◽  
Range Order ◽  
Statistical Thermodynamic ◽  
Range Order Parameter ◽  
Long Range Order ◽  
Short Range Order Parameter

The limitation of the long-range order parameter and the necessity of the short-range order parameter for the thermodynamic description of Pb()O3-type perovskites are discussed. Based on the discussion, a statistical thermodynamic model that takes into account the configuration of the neighboring B-site ions (B′ and B″ cations) was developed. A pair-correlation approximation was used in the calculation of the configurational entropy and the long-range coulombic interaction energy between the nearest B-site ions. The theoretical calculations using Pb(Sc1/2Ta1/2)O3 (PST) and Pb(Sc1/2Nb1/2)O3 (PSN) systems indicate that the short-range order parameter persists over a wide range of temperatures examined (0–1800 K) and that there possibly occur consecutive long-range order-disorder transitions in the configuration of B-site cations. The possibility of the existence of short-range ordering above the long-range order-disorder transition temperature was also examined using the annealed PSN specimen as a typical example of Pb()O3-type perovskites.

ENERGETIC EFFECT IN LIQUID ANTIMONY-INDIUM ALLOYS

1995 ◽  
Vol 09 (26n27) ◽  
pp. 1729-1738 ◽  
Author(s):  
R.N. SINGH ◽  
K.K. SINGH
Keyword(s):  
Liquid Phase ◽  
Order Parameter ◽  
Short Range ◽  
Short Range Order ◽  
Atomic Level ◽  
Range Order Parameter ◽  
Equiatomic Composition ◽  
Formation Model ◽  
Indium Alloys ◽  
Dependent Behaviour

The complex formation model has been used to extract the atomic level interactions in liquid Sb-In alloys. The phase diagram, the concentration fluctuations and the chemical short range order parameter indicate that the chemical complexes of the equiatomic composition (SbIn) exist in the liquid phase. The nature of interactions between Sb, In and the complexes (SbIn) in the liquid phase are attractive. The observed concentration dependent behaviour of activity, HM, GxsSxs and Scc(0) have been successfully explained.

Surface Ordering of MBE Grown 001 Ga1−xAlxAs- A Theoretical Study

1991 ◽  
Vol 241 ◽  
Author(s):  
Rita Trivedi ◽  
R. Venkatasubramanian
Keyword(s):  
Order Parameter ◽  
Short Range ◽  
Short Range Order ◽  
Theoretical Study ◽  
Flux Ratio ◽  
Range Order ◽  
Range Order Parameter ◽  
Mbe Growth ◽  
Short Range Order Parameter ◽  
Surface Migration

ABSTRACTThe kinetics of MBE growth of Ga1-x.,Alx,As is studied theoretically using the stochastic model of MBE growth based on the master equation approach and the random distribution approximation. The surface ordering phenomenon during the 001 growth of Ga0.5Al0.5 As is investigated as a function of the growth conditions. The atom pair interaction energy parameters for various surface configurations were obtained from the first principle calculations. The other model parameters needed in the description of the kinetic processes are obtained from the available experimental data. The ordering kinetics is studied as a function of fluxes, flux ratio and growth temperature. The degree of ordering is estimated in terms of the short range order parameter. The short range order parameter increases with temperature till 650°K and 750°K for cation to anion flux ratios 2 : 1 and 1 : 5, respectively. Beyond this critical temperature, the short range order parameter decreases. This critical temperature is identified as the kinetic order-disorder temperature. The order-disorder phenomenon observed in this theoretical study is explained in terms of the dependence of the surface migration rate of the cations on the growth temperature. The dependence on the order-disorder temperature on the flux ratio is attributed to decreased surface migration for larger flux ratios.

scholarly journals Concentration Fluctuation in Long Wavelength Limit in Liquid Magnesium Alloy

2011 ◽  
Vol 2 ◽  
pp. 47-49
Author(s):  
D Adhikari ◽  
B. P. Singh ◽  
I. S. Jha
Keyword(s):  
Order Parameter ◽  
Short Range ◽  
Short Range Order ◽  
Wave Length ◽  
Concentration Fluctuation ◽  
Chemical Order ◽  
Long Wavelength ◽  
Long Wave ◽  
Associated Solution Model ◽  
Associated Solution

The microscopic structure of MgSn liquid alloy at 1073K has been studied by using regular associated solution model. For this we have calculated the concentration fluctuation in long wave length limit [SCC(0)] and chemical short range order parameter (α1) of liquid MgSn alloy at 1073 K.Keywords: Binary Alloy; Complex; Chemical order; Microscopic FunctionThe Himalayan Physics Vol.2, No.2, May, 2011Page: 47-49Uploaded Date: 1 August, 2011

Pb()O3-type Perovskites: Part II. Short-range Order Parameter as a Criterion of the Distinction Between Relaxor and Normal Ferroelectrics

1997 ◽  
Vol 12 (8) ◽  
pp. 2127-2133 ◽  
Author(s):  
Su-Chan Kim ◽  
Hyun M. Jang
Keyword(s):  
Coherence Length ◽  
Order Parameter ◽  
Short Range ◽  
Short Range Order ◽  
Order Parameters ◽  
Range Order ◽  
Relaxor Behavior ◽  
Range Order Parameter ◽  
Short Range Order Parameter ◽  
Short Range Ordering

A classification scheme of Pb()O3-type perovskites with respect to the B-site order parameters was proposed based on the theoretical calculation of the short-range order parameter (σ) using the pair-correlation model. The calculated order parameters predict that a Pb()O3-type perovskite without any charge difference between B′ and B″ cations [e.g., Pb(Zr1/2Ti1/2)O3 (PZT)] is represented by a completely disordered state with the absence of a finite coherence length. On the other hand, a Pb()O3-type perovskite system having different ionic charges is characterized either by the short-range ordering with a nanoscale coherence length or by the macroscopic long-range ordering, depending on the magnitude of ionic charge difference between B′ and B″ ions. The normal ferroelectricity in Pb()O3-type complex perovskites was then correlated either with a completely disordered state (σ = 0) or with a perfectly ordered state (σ = 0), whereas the relaxor behavior was attributed to the nanoscale short-range ordering (0 < σ < 1) in the configuration of the B-site cations.

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