Atomic structure of (GeTe)m(Sb2Te3)n phase-change materials

Download

index.pdf

Date

2014

Author

Homurlu, Sibel

Metadata

Show full item record

Item Usage Stats

102
views

86
downloads

In this thesis, pulse phase resolved X-ray spectroscopy of four accretion powered millisecond pulsars which are IGR J00291+5934 , IGR J17498-2921 , XTE J0929-314 and XTE J1807-294 will be presented. Phase dependent changes during their outbursts will be checked for possible correlations of spectral parameters such as photon index and blackbody temperature with rotation phase using archive of Rossi X-ray Timing Explorer (RXTE) observations. In the analysis of IGR J17498-2921 in 2011 outburst , positive correlation is found between photon index and flux. In the analysis of XTE J0929-314 in 2002 outburst, negative correlation is found between photon index and blackbody temperature. In the analysis of XTE J1807-294 in 2003 outburst, about 150 days RXTE observation data is divided into 7 states, which consist of 3 flare and 4 non-flare states. In the first flare state analysis, negative correlation is found between blackbody temperature and photon index. In the second flare state analysis, positive correlation is found between blackbody temperature and photon index. In the second non-flare state analysis, positive correlation is found between flux and photon index. In the fourth non-flare state analysis, positive correlation is found between flux and photon index. On the other hand, correlation between blackbody temperature, photon index and flux is not found in the analysis of third flare state, first non flare state and third non-flare state analysis of XTE J1807-294 and in the analysis of IGR J00291+5934 in September 2008 outburst.

Subject Keywords

Density functionals., Molecular dynamics., Phase transformations (Statistical physics).

URI

http://etd.lib.metu.edu.tr/upload/12617823/index.pdf
https://hdl.handle.net/11511/23856

Collections

Graduate School of Natural and Applied Sciences, Thesis

Suggestions

OpenMETU
Core

Pulse phase resolved x-ray spectroscopy of four accretion powered millisecond pulsars Çolak, Sıdıka Merve; Baykal, Altan; Department of Physics (2014) In this thesis, pulse phase resolved X-ray spectroscopy of four accretion powered millisecond pulsars which are IGR J00291+5934 , IGR J17498-2921 , XTE J0929-314 and XTE J1807-294 will be presented. Phase dependent changes during their outbursts will be checked for possible correlations of spectral parameters such as photon index and blackbody temperature with rotation phase using archive of Rossi X-ray Timing Explorer (RXTE) observations. In the analysis of IGR J17498-2921 in 2011 outburst , positive corre...
Investigation of the dynamic properties of ferroelectric crystals close to phase transitions Kiracı, Ali; Erkoç, Şakir; Department of Physics (2015) In this thesis we investigated the dynamical properties of some ferroelectric crystals and ceramics under various temperature and pressure conditions close to the phase transitions. In particular, we focused on the Raman frequencies, damping constant and the activation energy of soft modes with the pseudospin-phonon coupling in some ferroelectric crystals exhibiting phase transitions. We predicted the critical behavior of the frequency related to the order parameter (spontaneous polarization) in the ferroel...
First order and second order phase transitions in quartz and related materials Lider, Mustafa Cem; Yurtseven, Hasan Hamit; Department of Physics (2017) The mechanism of the phase transitions in quartz and in the related materials is investigated. First order and second order transitions are explained on the basis of various models using experimental data from literature. Inparticular, the Landau phenomenological theory is employed in terms of the order parameters and the temperature- pressure (T-P) phase diagram is constructed for those materials of interest. The sym- metry change of crystal structure is also analyzed by using group theory. The thermodynam...
Magnetic monitoring approach to kinetics of phase transformations in multicomponent alloy systems Duman, Nagehan; Mekhrabov, O. Mekhrabov; Akdeniz, Mahmut Vedat; Department of Metallurgical and Materials Engineering (2012) It is of great importance for a materials scientist both from fundamental and applicability aspects to have better understanding of solid-state phase transformations and its kinetics responsible for micro-/nano-structure development in alloys and corresponding physical and mechanical properties. Transformation kinetics can be analyzed by various experimental techniques such as thermal analysis, laborious electron microscopy combined with extensive image analysis or by measuring changes in electrical resisti...
Two dimensional modeling of electromagnetic radiation and scattering by spectral element method Mahariq, İbrahim; Tarman, Işık Hakan; Kuzuoğlu, Mustafa; Department of Engineering Sciences (2014) In this thesis, the spectral element method is utilized in numerical modeling of two-dimensional, frequency-domain electromagnetic scattering and radiation problems. We perform domain truncation by the well-known perfectly matched layer (PML) and provide the corresponding formulation. The attenuation factor associated with the PML formulation is optimized so that the best accuracy is achieved for a wide range of Gauss- Legendre -Lobatto grids per wavelength. The optimality of the provided attenuation factor...

Citation Formats

S. Homurlu, “Atomic structure of (GeTe)m(Sb2Te3)n phase-change materials,” M.S. - Master of Science, Middle East Technical University, 2014.