Show/Hide Menu
Hide/Show Apps
Logout
Türkçe
Türkçe
Search
Search
Login
Login
OpenMETU
OpenMETU
About
About
Open Science Policy
Open Science Policy
Open Access Guideline
Open Access Guideline
Postgraduate Thesis Guideline
Postgraduate Thesis Guideline
Communities & Collections
Communities & Collections
Help
Help
Frequently Asked Questions
Frequently Asked Questions
Guides
Guides
Thesis submission
Thesis submission
MS without thesis term project submission
MS without thesis term project submission
Publication submission with DOI
Publication submission with DOI
Publication submission
Publication submission
Supporting Information
Supporting Information
General Information
General Information
Copyright, Embargo and License
Copyright, Embargo and License
Contact us
Contact us
Investigation of the incommensurate (INC) phase between α and β phases in quartz and related materials
Download
12626179.pdf
Date
2021-2-10
Author
Ateş, Simge
Metadata
Show full item record
This work is licensed under a
Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License
.
Item Usage Stats
217
views
331
downloads
Cite This
Incommensurate (INC) phase as an intermediate sinusoidal phase which exists in anarrow temperature range (∼1.3◦C) between the low-temperatureαand the high-temperatureβphases in quartz, is investigated extensively. The phase transitions oftheα-INC and INC-βoccurring as first order and second order type, respectively,are studied using the experimental data from the literature. Order-disorder transi-tion between theαandβquartz through the incommensurate phase is described bytemperature and pressure dependence of the experimentally measurable macroscopicparameters in relation to the microscopic order parameter according to various mod-els, mainly the Landau phenomenological model.Our methods in this study form a guide to investigate crystals with similar phasediagram with quartz as tridymite and cristobalite, and incommensurate phases in someother materials with similar crystal structure to quartz such asNaNO2,K2SeO4andAlPO4.
Subject Keywords
Landau model
,
Phase transitions
,
Incommensurate phase
,
Quartz
URI
https://hdl.handle.net/11511/89831
Collections
Graduate School of Natural and Applied Sciences, Thesis
Suggestions
OpenMETU
Core
Landau phenomenological model for the alpha-INC (incommensurate)-beta transition in quartz
Yurtseven, Hasan Hamit (2021-08-01)
The temperature dependence of the order parameters eta (alpha-phase) and xi (INC - incommensurate phase) are calculated in the presence of the electric field for the alpha-INC-beta transition in quartz by the Landau mean field theory. Landau phenomenological model with the linear (eta xi) and quadratic (eta(2)xi(2)) coupling is introduced to investigate mainly the nature of the INC phase between alpha (ordered) and beta (disordered) phases in quartz. The temperature dependence of the inverse susceptibilitie...
Calculation of the Brillouin frequencies close to phase transitions in NaNO2
Yurtseven, Hasan Hamit (2002-01-01)
We calculate here the Brillouin frequencies of the L-mode [010], [001] and [100] of NaNO2 for the phase transitions from the paraelectric phase to the sinusoidal anti-ferroelectric phase near the Neel temperature (T-N = 437.7 K) and to the ferroelectric phase near the critical temperature (T-c = 436.3 K) in this crystalline system. For calculating the frequencies, we use the thermal expansivity data for the phase regions considered, under the assumption that the mode Gruneisen parameter determined for each ...
Analysis of the Specific Heat for the Transitions of the Phases I-II-III-IV in (N(CH3)(4))(2)CUCl4 Crystal
Yurtseven, Hasan Hamit (2008-01-01)
The temperature dependence of the specific heat C-p is analyzed here using the experimental data according to a power-law formula with the critical exponent a for the transitions of commensurate (I), incommensurate (II) and the ferroelastic (III and IV) phases in (N(CH3)(4))(2)CUCl4 crystal. From our analysis, we extract the value of a approximate to 0 above and below T-c for the successive phase transitions of which is expected from the mean field theory (alpha =0 discontinuity), XY model (alpha =0 log) an...
Calculation of the soft mode frequency for the alpha beta transition in quartz
Yurtseven, Hasan Hamit (null; 2015-09-18)
The Raman frequencies of the lattice modes (147 cm-1 and 207 cm-1 are analyzed for the α-β transition in quartz according to a power-law formula with the critical exponent by using the experimental data. The temperature dependence of the Raman frequency is associated with the order parameter (polarization P) for this transition in the quartz crystal. The damping constant of the lattice modes studied here is calculated using the Raman frequencies at various temperatures for the α-β transition in quartz (Tc =...
Calculation of the specific heat for ND4Br close to phase transitions
Yurtseven, Hasan Hamit (2002-03-01)
This study gives our calculation for the specific heat close to the phase transitions from the disordered (phase 11) to the antiferro-ordered (phase 111) and to the ferro-ordered (phase IV) phases in ND4Br. We calculate the specific heat C-VI due to the nearest-neighbour interactions between ND4+. tetrahedra in the ND4Br crystal, by using an Ising model superimposed on an Einstein and/or Debye model which we have developed. Our calculated specific heat C-VI agrees well with the experimental C-p data for the...
Citation Formats
IEEE
ACM
APA
CHICAGO
MLA
BibTeX
S. Ateş, “Investigation of the incommensurate (INC) phase between α and β phases in quartz and related materials,” Ph.D. - Doctoral Program, Middle East Technical University, 2021.
