A study is performed on characteristics of lattice dynamics in the initially ordered ternary Ni3(Fe1-xNbx) (x = 0 to 10 at.%) alloys using high temperature X-ray diffractometry for the temperature range from 300 K to 1300 K. Aspects investigated included temperature and concentration dependencies of the full mean square atomic displacements U(f)2BAR, the Debye characteristic temperature THETA(D), and linear thermal expansion coefficient alpha. It is found that the U(f)2BAR, THETA(D), and alpha parameters show anomalous change at temperatures where the alloys are subjected to order-disorder phase transitions. It is further found that Nb addition results in the considerable increase in the parameters U(f)2BAR and alpha and decrease in THETA(D). Moreover, the addition of Nb stabilizes Ni3Fe ordered structure and shifts the order-disorder transition to higher temperature.


Low-temperature Raman scattering in TlGaxIn1-xS2 layered mixed crystals: Compositional dependence of the mode frequencies and line shapes
Hasanlı, Nızamı (Institute of Physics, Polish Academy of Sciences, 2005-12-01)
The Raman spectra of TlGaxIn1-xS2 layered mixed crystals were studied for a, wide range of composition (0 <= x <= 1) at T = 50 K. The effect of crystal disorder on the line width broadening of the Raman-active modes are discussed. The asymmetry in the Raman line shape is analyzed for two interlayer and intralayer modes exhibiting one-mode behavior.
Approximate analytical solutions of the pseudospin symmetric Dirac equation for exponential-type potentials
Arda, Altu; Sever, Ramazan; TEZCAN, CEVDET (Wiley, 2009-10-01)
The solvability of The Dirac equation is studied for the exponential-type potentials with the pseudospin symmetry by using the parametric generalization of the Nikiforov-Uvarov method. The energy eigenvalue equation, and the corresponding Dirac spinors for Morse, Hulthen, and q-deformed Rosen-Morse potentials are obtained within the framework of an approximation to the spin-orbit coupling term, so the solutions are given for any value of the spin-orbit quantum number kappa = 0, or kappa not equal 0. (C) 200...
Bound states of the Dirac equation for the PT-symmetric generalized Hulthen potential by the Nikiforov-Uvarov method
Egrifes, H; Sever, Ramazan (Elsevier BV, 2005-09-05)
The one-dimensional Dirac equation is solved for the PT-symmetric generalized Hulthen potential. The Nikiforov-Uvarov method which is based on solving the second-order linear differential equations by reduction to a generalized equation of hypergeometric type is used to obtain exact energy eigenvalues and corresponding eigenfunctions.
Parameter Identification in MHD Duct Flow Cauchy Problem using the DRBEM
Tezer, Münevver (2018-08-31)
In this study, the Hartmann number (Ha) is identified through the inverse formulation of Cauchy problem for magnetohydrodynamic (MHD) flow in a duct with insulated but no-slip or variably slipping walls. The solutions for direct and inverse problems are obtained using the dual reciprocity boundary element method (DRBEM), and Tikhonov regularization with L-curve method is used for solving ill-conditioned linear system of equations resulted from the inverse problem. The velocity and the induced magnetic field...
Approximate l-state solutions of the D-dimensional Schrodinger equation for Manning-Rosen potential
IKHDAİR, SAMEER; Sever, Ramazan (Wiley, 2008-11-01)
The Schrodinger equation in D-dimensions for the Manning-Rosen potential with the centrifugal term is solved approximately to obtain bound states eigensolutions (eigenvalues and eigenfunctions). The Nikiforov-Uvarov (NU) method is used in the calculations. We present numerical calculations of energy eigenvalues to two- and four-dimensional systems for arbitrary quantum numbers n and 1, with three different values of the potential parameter alpha. It is shown that because of the interdimensional degeneracy o...
Citation Formats
A. Mehrabov, “HIGH-TEMPERATURE X-RAY-DIFFRACTION STUDIES OF LATTICE-DYNAMICS IN NI3(FE,NB) ORDERED ALLOYS,” ACTA PHYSICA POLONICA A, pp. 571–578, 1994, Accessed: 00, 2020. [Online]. Available: https://hdl.handle.net/11511/35087.