Fizik Bilim Dalı Yayın Koleksiyonu

Permanent URI for this collectionhttps://hdl.handle.net/20.500.12416/4363

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Citation - WoS: 4
Citation - Scopus: 4
Temperature-dependent absorption edge and photoconductivity of Tl 2In2S3Se layered single crystals
(Elsevier Science Sa, 2013) Guler, I.; Güler, İpek; Ambrico, M.; Ligonzo, T.; Gasanly, N. M.; 101531; Ortak Dersler Bölümü
Temperature variation of indirect band gap of Tl2In2S3Se layered single crystals were obtained by means of absorption and photoconductivity measurements. The temperature coefficient of -7.1 x 10(-4) eV/K from absorption measurements in the temperature range of 10-300 K in the wavelength range of 520-1100 nm and -5.0 x 10(-4) eV/K from PC measurements in the temperature range of 132-291 K in the wavelength range of 443-620 nm upon supplying voltage V = 80 V were obtained. From the analysis of dark conductivity measurements in the temperature range of 150-300 K, conductivity activation energy was obtained as 0.51 eV above 242 K. The degree of the disorder, the density of localized states near Fermi level, the average hopping distance and average hopping energy of Tl2In2S3Se crystals were found as, 1.9 x 10(5) K, Nf = 4 x 10(20) cm(-3)eV(-1), 29.1 angstrom and 24.2 meV in the temperature range of 171-237 K, respectively. Activation energy of hopping conductivity at T = 171 K was obtained as 41.3 meV and the concentration of trapping states was found as 1.6 x 10(19) cm(-3). (C) 2012 Elsevier B.V. All rights reserved.
Citation - WoS: 3
The Important Role of N(2)(CH3)(4) Ion in the Phase-Transition Mechanism of [N(CH3)(4)](2)ZnBr4
(Ieee-inst Electrical Electronics Engineers inc, 2020) Kiraci, Ali; Kiracı, Ali; Ortak Dersler Bölümü
The chemical shift of the N(2)(CH3)(4) ion, which has been found to exhibit the similar anomalous behavior of the monoclinic angle $\Delta \beta $ , was related to the order parameter to evaluate the temperature dependence of the linewidth (damping constant) for N-14 nuclear magnetic resonance spectrum of this crystal in terms of the dynamic Ising models, namely the pseudospin-phonon-coupled (PS) and the energy fluctuation (EF) models. The results from both PS and EF models were successful to explain the abnormal behavior of the linewidth in the vicinity of the phase-transition temperature of ${T}_{C}= {287.6}$ K, when compared with the observed linewidth of the transverse acoustic soft mode in this crystal. As an extension of this work, the N-14 relaxation time and the values of the activation free energy were calculated as a function of temperature. The results indicate that the ferroelastic-paraelastic phase transition in this compound is of the order-disorder type.

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