The Important Role of N(2)(CH3)(4) Ion in the Phase-Transition Mechanism of [N(CH3)(4)](2)ZnBr4

Kiraci, Ali
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.


The electronic structure of a quantum well under an applied electric field
Sari, H; Ergun, Y; Sokmen, I; Tomak, Mehmet (Elsevier BV, 1996-01-01)
The effects of an applied electric field on quantum well subband energies are calculated variationally within the effective mass approximation for model potential profiles. The concept of a quasi-bound state is examined critically. For higher electric field values it is shown that the quasi-bound state approximation for the ground and first excited state of the electron, and for the ground state of the hole is valid. (C) 1996 Academic Press Limited
Estimation of Articulatory Trajectories Based on Gaussian Mixture Model (GMM) With Audio-Visual Information Fusion and Dynamic Kalman Smoothing
ÖZBEK, İbrahim Yücel; Hasegawa-Johnson, Mark; Demirekler, Mübeccel (Institute of Electrical and Electronics Engineers (IEEE), 2011-07-01)
This paper presents a detailed framework for Gaussian mixture model (GMM)-based articulatory inversion equipped with special postprocessing smoothers, and with the capability to perform audio-visual information fusion. The effects of different acoustic features on the GMM inversion performance are investigated and it is shown that the integration of various types of acoustic (and visual) features improves the performance of the articulatory inversion process. Dynamic Kalman smoothers are proposed to adapt t...
The mean field model with P-2 theta(2) coupling for the smectic A-smectic C* phase transition in liquid crystals
Salihoglu, S; Yurtseven, Hasan Hamit; Giz, A; Kayisoglu, D; Konu, A (Informa UK Limited, 1998-01-01)
Using mean field theory with a P(2)theta (2) coupling term in the free energy expansion, we calculate the polarization as a function of temperature for the smectic A-smectic C* phase transition in a liquid crystalline material. Our calculated polarization values are in good agreement with the experimental data.
Clarification of issues on the closed-form Green's functions in stratified media
Aksun, MI; Dural Ünver, Mevlüde Gülbin (Institute of Electrical and Electronics Engineers (IEEE), 2005-11-01)
The closed-form Green's functions (CFGF), derived for the vector and scalar potentials in planar multilayer media, have been revisited to clarify some issues and misunderstandings on the derivation of these Green's functions. In addition, the range of validity of these Green's functions is assessed with and without explicit evaluation of the surface wave contributions. As it is well-known, the derivation of the CFGF begins with the approximation of the spectral-domain Green's functions by complex exponentia...
Effects of screening on the two-dimensional electron transport properties in modulation doped heterostructures
Sen, O; Beşikci, Cengiz; Tanatar, B (Elsevier BV, 1998-06-01)
The effects of screening on the polar optical phonon scattering rates and on the transport properties of the two-dimensional electron gas in AlGaAs/GaAs modulation doped heterostructures have been investigated through Monte Carlo simulations incorporating the three valleys of the conduction band, size quantization in the Gamma valley and the lowest three subbands in the quantum-well. At typical sheet densities observed in modulation doped field-effect transistors, screening considerably affects the electron...
Citation Formats
A. Kiraci, “The Important Role of N(2)(CH3)(4) Ion in the Phase-Transition Mechanism of [N(CH3)(4)](2)ZnBr4,” IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL, pp. 1053–1058, 2020, Accessed: 00, 2020. [Online]. Available: