Fizik Bilim Dalı Yayın Koleksiyonu
Permanent URI for this collectionhttps://hdl.handle.net/20.500.12416/4363
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Browsing Fizik Bilim Dalı Yayın Koleksiyonu by Subject "Crystals"
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Article The Important Role of N(2)(CH3)(4) Ion in the Phase-Transition Mechanism of [N(CH3)(4)](2)ZnBr4(2020) Kiracı, AliThe 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.Article Thermoluminescence in gallium sesquisulfide single crystals: usual and unusual heating rate dependencies(2018) Guler, I.; Isik, M.; Gasanova, L.; Mahammadov, A.; Gasanly, N.Thermoluminescence (TL) experiments were conducted for Ga2S3 crystals to obtain information about trapping parameters. TL measurements were performed from 10 to 300 K with varying heating rates in the range of 0.2–0.8 K/s. Two TL glow peaks centered at 44 K (peak A) and 91 K (peak B) were observed at heating rate of β = 0.5 K/s. For peak A, TL intensity decreased whereas that for peak B increased with elevating the heating rates that means anomalous heating rate occurred for peak B. TL glow curves were analyzed using initial rise method to find activation energies of traps. Distribution of trap centers was investigated using Tmax − Tstop method. Quasi-continuous distributions with increasing activation energies from 40 to 135 meV and 193 to 460 meV were attributed to trap centers A and B, respectively.
