Ortak Dersler Bölümü

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Analysis and Mathematical Computation of Some Dynamic Function for Strontium Stannate
(Taylor & Francis Ltd, 2021) Askun, Ali Riza; 56475; 01. Çankaya Üniversitesi; 09. Rektörlük; 09.01. Ortak Dersler Bölümü
The frequency and full width at half maximum (FWHM) data of the A(g) Raman modes (95.4, 231.4 and 263.2 cm(-1)) in strontium stannate crystal have been analyzed using the Balkanski model and the fitting parameters were determined. Also, the isobaric Gruneisen parameter of A(g) Raman modes studied here was computed below the room temperature. This computation was performed from the unit cell volume and the observed frequency data of this crystal. Finally, values of the activation energy were extracted close to the structural phase transition temperatures of 160 and 265 K using the observed FWHM data of strontium stannate.
Analysis and Mathematical Computation of Some Dynamic Functions for the Guanidine Zinc Sulfate
(Taylor & Francis Ltd, 2021) Askun, A. R.; Kiraci, A.; 56475; 09.01. Ortak Dersler Bölümü; 09. Rektörlük; 01. Çankaya Üniversitesi
A power-law formula with a critical exponent alpha was used to analyze the anomalous behavior of the specific heat for guanidine zinc sulfate (GZS) crystal close to the phase transition temperature of T-c = 178.4 K. The obtained values of 0.13 and 0.14 for alpha below (T < T-c) and above (T> T-c) the phase transition temperature, respectively, were almost the same value of 0.13 (1/8) that predicted from the 3-D (sing model. Also, the internal energy U, the entropy S and the free energy G of this crystal were calculated as a function of temperature dose to the phase transition temperature of T-c = 178.4 K.
Analysis of the Specific Heat and the Free Energy and Calculation of the Entropy and the Internal Energy of [N(ch3)4]2mnbr4 Close To the Phase Transition
(Taylor & Francis Ltd, 2021) Kiraci, A.; 42475; 09.01. Ortak Dersler Bölümü; 09. Rektörlük; 01. Çankaya Üniversitesi
The critical behavior of the specific heat and the Gibbs free energy of [N(CH3)(4)](2)MnBr4 was analyzed using the 'sing model close to the phase transition temperature of T-c = 276.5 K. Obtained value of alpha=0.02 from the Gibbs free energy and from the specific heat approximately 2.0 K and 1.4 K, respectively, below Tc (ferroelastic phase) and also deduced value of alpha= 0.04 from the specific heat approximately 0.3 K above T-c (paraelastic phase) can be compared with that predicted from mean field theory (alpha = 0). Also, the entropy and the internal energy of this crystal were predicted.
Citation - WoS: 3
Citation - Scopus: 2
Calculation of the Infrared Frequencies as a Function of Temperature Using the Volume Data in the Ferroelectric Phase of Nano2
(Taylor & Francis Ltd, 2014) Kiraci, A.; Yurtseven, H.; 42475; 09.01. Ortak Dersler Bölümü; 09. Rektörlük; 01. Çankaya Üniversitesi
We calculate the temperature dependence of the infrared frequencies of the TO and LO modes with the symmetries of A(1), B-1 and B-2 mainly in the ferroelectric phase of NaNO2. This calculation is carried out using the volume dependence of the infrared frequencies through the mode Gruneisen parameter in this crystal. The volume dependences of the infrared frequencies are fitted to the observed frequencies by using constant mode Gruneisen parameter in the ferroelectric phase of NaNO2. Our results show that this method of calculating the infrared frequencies describes the observed behaviour of NaNO2 adequately.
Citation - WoS: 3
Citation - Scopus: 4
Damping Constant and the Inverse Relaxation Time Calculated as a Function of Pressure Using the X-Ray Diffraction Data Close To the Cubic-Tetragonal Phase Transition in Srtio3
(Taylor & Francis Ltd, 2019) Kiraci, A.; Yurtseven, H.; 42475; 09.01. Ortak Dersler Bölümü; 09. Rektörlük; 01. Çankaya Üniversitesi
The damping constant is calculated as a function of pressure at room temperature using the normalized intensity as an order parameter near the cubic-tetragonal phase transition in SrTiO3. The observed X-ray diffraction data are used for the normalized intensities to calculate the damping constant () from the pseudospin-phonon (PS) coupled model and the energy fluctuation (EF) model, which is fitted to the observed FWHM data from the literature for comparison. Using the calculated values, the pressure dependence of the inverse relaxation time () is predicted close to the cubic-tetragonal phase transition in SrTiO3. Our calculated damping constant from both models explains the observed FWHM satisfactorily and our prediction of the inverse relaxation time can also be compared with the experimental measurements when they are available in the literature.
Citation - WoS: 2
Citation - Scopus: 1
Inter-Laboratory Comparison Scheme for Fuel Sector, Labkar in Turkey
(Springer, 2009) Bayrak, Ozlem Turker; Okandan, Ender; Uckardes, Hale; 56416; 09.01. Ortak Dersler Bölümü; 09. Rektörlük; 01. Çankaya Üniversitesi
Fuel sector is one of the powerful sectors in Turkish industry. The implementation of a new law for regulating the fuel sector had enforced the quality control of fuels sold to public. This resulted in several accredited fuel-testing laboratories to emerge. Thus, a scheme to evaluate their proficiency in measurements became an important requirement. The inter-laboratory comparison scheme LABKAR for gasoline, diesel oil, LPG, lubricating oil and biodiesel samples have evolved to fulfill this need. In this paper, LABKAR is introduced; the results obtained from the program are analyzed and discussed. The kernel densities of the participants' results show that the use of robust mean as a consensus value is appropriate for fuel samples. Although the number of rounds is not enough to derive strict conclusions, it is seen that the performance of the scheme based on the standard deviations and coefficient of variations is improving in each round. It has been observed that the number of laboratories receiving "action" or "warning" is decreasing, which indicates that they are benefiting from the scheme.
Investigating Information Seeking Process Using Think-Aloud Protocol of Students Living in Rural Areas
(Springer international Publishing Ag, 2022) Akkoyunlu, Buket; Cetin, Nihal Menzi; 8539; 09.01. Ortak Dersler Bölümü; 09. Rektörlük; 01. Çankaya Üniversitesi
In this study, we investigated how students in a rural secondary school searched for online information for their school assignments, and we employed the think-aloud protocol to reveal students' information seeking processes. In this study, three students were given three search tasks that were similar to their school assignments and they were asked to search the web for the tasks. To obtain data from each student's web search, we used screen-capture software and collected audio and video records. Recordings were subsequently transcribed and analyzed. Results showed that while the students completed the easy and medium-level search tasks to a great extent, they had difficulty in completing the difficult task. In addition, students performed the tasks with various steps and durations. Emotions such as hesitation, satisfaction, frustration and anxiety were observed in the students while they were performing the tasks. The results were also discussed in terms of the characteristics of the information seeking process.
Investigation of the Anomalous Behavior of the Linewidth (Damping Constant) for the Raman Ag Modes in Srsno3 Ceramic
(Taylor & Francis Ltd, 2022) Kiraci, A.; 42475; 09.01. Ortak Dersler Bölümü; 09. Rektörlük; 01. Çankaya Üniversitesi
The anomalous behavior of the linewidth (damping constant) for the Raman A(g) modes of 223 cm(-1) and 260 cm(-1) that contribute to the phase transition mechanism of SrSnO3 ceramic close to the phase transition temperatures of T-C1= 650 K and T-C2= 530 K, respectively, was calculated as function of temperature from the pseudospin-phonon coupled (PS) and the energy fluctuation (EF) models below (T < T-C) and above (T > T-C) the phase transition temperatures of T-C1 and T-C2. For this calculation, the frequency shift of these modes were associated as the order parameter and disorder parameter below and above T-C, respectively. Our results are in good agreement with the observed linewidth of these 223 cm(-1) and 260 cm(-1) Raman A(g) modes. In addition, these two models (PS and EF) were used to deduce the values of the activation energy for SrSnO3 ceramic below and above the phase transition temperatures of T-C1 and T-C2.
Citation - WoS: 4
Citation - Scopus: 4
Order-Disorder Transition in the Ferroelectric Litao3
(Taylor & Francis Ltd, 2019) Yurtseven, Hamit; Kiraci, Ali; 42475; 09.01. Ortak Dersler Bölümü; 09. Rektörlük; 01. Çankaya Üniversitesi
The temperature dependences of the damping constant and the relaxation time are calculated by using the Raman frequencies of a* and the lowest A(1) (TO) phonons in the ferroelectric phase close to the ferroelectric-paraelectric transition in LiTaO3 (T-C = 963 K). Both calculations are performed by considering the frequency as an order parameter for the pseudospin-phonon (PS) and the energy fluctuation (EF) models using the observed data from the literature. Values of the activation energies of this crystal are also deduced by using both models in this crystal. Our results show that the PS and EF models can describe the observed behavior adequately for the order-disorder transition in LiTaO3.
Citation - Scopus: 1
Phenomenological Approaches on the Nd³⁺ Doped Ferroelectric Labgeo5
(Taylor & Francis Ltd, 2021) Kiraci, A.; Yurtseven, Hamit; Kara, N.; 09.01. Ortak Dersler Bölümü; 09. Rektörlük; 01. Çankaya Üniversitesi
Two phenomenological models, namely the compressible Ising model and Landau model, have been used to analyze the specific heat and the dielectric constant data, respectively for the pure and Nd3+ doped LaBGeO5 (LBG) crystals. The critical exponent of the specific heat was extracted in both ferroelectric and paraelectric phases of the crystals studied here within the temperature intervals of [T - T-C vertical bar < 4 K. The extracted values of the critical exponent were then used to predict some thermodynamic quantities such as the enthalpy, entropy, and the Gibbs free energy. Regarding the analysis of dielectric constant data within the framework of the Landau theory, the observed values of the birefringence were associated with the order parameter below the transition temperature T-c. The Landau coefficients a(0) and a(4) were determined. Our results indicate a second-order phase transition mechanism.
Citation - WoS: 2
Citation - Scopus: 3
A Phenomenological Study on Ferroelectric Β-Glycine
(Taylor & Francis Ltd, 2021) Kiraci, A.; 42475; 09.01. Ortak Dersler Bölümü; 09. Rektörlük; 01. Çankaya Üniversitesi
The anomalous behavior of the specific heat for beta-glycine was analyzed in terms of the compressible Ising model approximately 5 K below and above the ferrelectric-paraelectric phase transition temperature of T-C =252 K. The obtained value of the critical exponent alpha =0.12 in the ferroelectric phase (T < TC) was consistent with that predicted from the 3-d Ising model (alpha =0.13), while the obtained value of alpha =0.32 in the paraelectric phase (T > TC) was consistent with that predicted from the 2-d potts model (alpha =0.30). Some thermodynamic quantities such as the internal energy, the entropy and the free energy of beta-glycine were then predicted in terms of these extracted values of the critical exponents close to the phase transition temperature of TC. Our calculated values of the thermodynamic quantities are in good agreement with the observed data.
Citation - WoS: 1
Citation - Scopus: 1
Pressure Dependence of the Raman Frequency Calculated From the Volume Data Close To the Ferroelectric-Paraelectric Transition in Pbtio3
(Taylor & Francis Ltd, 2017) Kiraci, Ali; Yurtseven, Hamit; 42475; 09.01. Ortak Dersler Bölümü; 09. Rektörlük; 01. Çankaya Üniversitesi
We calculate the pressure dependence of the Raman frequencies of some Raman modes by using the observed volume data through the mode Gruneisen parameters for the ferroelectri-paraelectric transition in PbTiO3. The mode Gruneisen parameters which we have determined using the observed Raman frequencies for the soft modes, increase considerably with increasing pressure toward the transition pressure (PC similar to 11 GPa) from the tetragonal (ferroelectric) to the cubic (paraelectric) phase in PbTiO3. Variation of the mode Gruneisen parameter with the pressure is rather smooth for the other Raman modes studied as compared to the drastic change at PC for the soft modes in this ferroelectric material. Raman frequencies (energy shifts) of the modes which we have calculated, decrease from the ferroelectric to the paraelectric phase with the exception of the optical modes of E(3LO) and E(3TO) whose Raman frequencies increase with increasing pressure. This decrease and/or increase in the energy shifts for the Raman modes which we have calculated as also observed experimentally, shows a continuous manner, indicating a second order character rather that the first order transition from the tetragonal to the cubic phase in PbTiO3.
A Study on How To Equip Students With Scientific Communication Skills
(Springer international Publishing Ag, 2018) Akkoyunlu, Buket; Cetin, Nihal Menzi; 8539; 09.01. Ortak Dersler Bölümü; 09. Rektörlük; 01. Çankaya Üniversitesi
The purpose of this study was to investigate the effects of scientific communication (SC) curriculum on blog writing skills of sixth-grade students, and opinions of the students and teachers about the curriculum. Through the curriculum, it was aimed to teach students the ability to access and evaluate information, organize information and share it by writing a blog. Students were given three different writing assignments and were asked to share them in their blogs. The first assignment was given for adapting to the writing process. The second and third assignments were assessed to determine the effect of SC curriculum on blog writing skills. At the end of the process, teachers and students were asked about their opinions on SC curriculum and blog writing. Study results revealed that SC curriculum had positive effects on research and writing skills development of the students, and showed that the curriculum was supportive in reaching the course-specific goals.
Citation - Scopus: 1
Survey and Evaluation on Modelling of Next-Day Electricity Prices
(Springer New York LLC, 2014) Bayrak, Ö.T.; Weber, G.-W.; Yıldırım, M.H.; 56416; 09.01. Ortak Dersler Bölümü; 09. Rektörlük; 01. Çankaya Üniversitesi

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