Journal articles: 'Debye behaviour'

1

Hagopian, Sair, and Scott L. Whittenburg. "Deviations from Stokes-Einstein-Debye behaviour in pyridazine." Journal of Molecular Liquids 45, no. 3-4 (April 1990): 273–82. http://dx.doi.org/10.1016/0167-7322(90)80035-i.

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Koenderink, G. H., and A. P. Philipse. "On Stokes-Einstein and Debye behaviour in colloidal fluids." Le Journal de Physique IV 10, PR7 (May 2000): Pr7–295—Pr7–298. http://dx.doi.org/10.1051/jp4:2000759.

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Tripathy, Chinmayee, Devraj Singh, and Rita Paikaray. "Behaviour of elastic and ultrasonic properties of curium monopnictides." Canadian Journal of Physics 96, no. 5 (May 2018): 513–18. http://dx.doi.org/10.1139/cjp-2017-0491.

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The temperature-dependent elastic and ultrasonic properties of curium monopnictides CmPn (Pn = N, P, As, Sb) have been explored in the present investigation. The second- and third-order elastic constants have been calculated using Coulomb and Born–Mayer potentials using lattice and hardness parameters. Mechanical parameters, such as Young’s modulus, bulk modulus, shear modulus, tetragonal modulus, anisotropic factor, and Poisson’s ratio, have been computed with second-order elastic constants. These materials fulfilled the requirement of the Born stability criterion. The toughness or fracture ratio is found to be more than 0.57 in CmPn, which indicates their brittle nature. In addition, the ultrasonic wave velocity, Debye average velocity, Debye temperature, thermal relaxation time, thermal conductivity, acoustic coupling constant, and ultrasonic attenuation have also been computed along ⟨100⟩, ⟨110⟩, ⟨111⟩ directions at room temperature. The results are discussed in correlation with other similar types of the materials.

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Costa, B. F. O., J. Cieslak, and S. M. Dubiel. "Anomalous behaviour of the Debye temperature in Fe-rich Fe–Cr alloys." Journal of Alloys and Compounds 492, no. 1-2 (March 2010): L1—L4. http://dx.doi.org/10.1016/j.jallcom.2009.11.067.

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Calderwood, J. H. "On the physical mechanism giving rise to debye behaviour in dielectric media." Journal of Molecular Liquids 49 (September 1991): 119–31. http://dx.doi.org/10.1016/0167-7322(91)80070-k.

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Lehnert, B. "Electron plasma oscillations at arbitrary Debye lengths." Journal of Plasma Physics 45, no. 3 (June 1991): 407–14. http://dx.doi.org/10.1017/s0022377800015804.

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A solution is presented for electron plasma oscillations in a thermalized plasma, at arbitrary ratios of the Debye length AλD and the perturbation wavelength λ. The limit λD≪λ corresponds to the conventional fluid-like theory of small particle excursions, whereas λD≫λ corresponds to the free-streaming limit of strong kinetic phase mixing due to large particle excursions. A strong large-Debye-distance (LDD) effect already appears when λD ≳ λ. The initial amplitude of the fluid-like contribution to the macroscopic density perturbation then becomes small compared with the contribution from the free-streaming part. As a consequence, only a small fraction of the density perturbation remains after a limited number of kinetic damping times of the free-streaming part. The present analysis can be considered as a first exercise in an attempt to tackle the far more difficult problem of large-Larmor-radius (LLR) effects in a magnetized plasma. The analysis further shows that a representation in terms of normal modes of the form exp (— iωt) leads to amplitude factors of these modes that are related to each other and that depend on the combined free-streaming and fluid behaviour of the plasma. Consequently, these modes are coupled and cannot be treated as independent of each other.

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Righetti, Pier Giorgio, Soffia Magnusdottir, Cecilia Gelfi, and Massimiliano Perduca. "Behaviour of inorganic and organic cations in the Debye–Hückel layer of DNA." Journal of Chromatography A 920, no. 1-2 (June 2001): 309–16. http://dx.doi.org/10.1016/s0021-9673(01)00695-1.

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Starzonek, Szymon, Sylwester J. Rzoska, A. Drozd-Rzoska, Sebastian Pawlus, Ewelina Biała, Julio Cesar Martinez-Garcia, and Ludmila Kistersky. "Fractional Debye–Stokes–Einstein behaviour in an ultraviscous nanocolloid: glycerol and silver nanoparticles." Soft Matter 11, no. 27 (2015): 5554–62. http://dx.doi.org/10.1039/c5sm00266d.

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9

Feranchuk, I. D., A. A. Minkevich, and A. P. Ulyanenkov. "About non-Gaussian behaviour of the Debye-Waller factor at large scattering vectors." European Physical Journal Applied Physics 24, no. 1 (September 3, 2003): 21–26. http://dx.doi.org/10.1051/epjap:2003058.

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Jyoti and Rakhee Malik. "Behaviour of TSI in Magnetized Plasmas for different Plasma Oscillation to Debye Wavelength ratio." Journal of Physics: Conference Series 823 (April 19, 2017): 012028. http://dx.doi.org/10.1088/1742-6596/823/1/012028.

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Jánosfalvi, Zs, J. Hakl, and P. F. de Châtel. "Larmor Precession and Debye Relaxation of Single-Domain Magnetic Nanoparticles." Advances in Condensed Matter Physics 2014 (2014): 1–10. http://dx.doi.org/10.1155/2014/125454.

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The numerous phenomenological equations used in the study of the behaviour of single-domain magnetic nanoparticles are described and some issues clarified by means of qualitative comparison. To enable a quantitativeapplicationof the model based on the Debye (exponential) relaxation and the torque driving the Larmor precession, we present analytical solutions for the steady states in presence of circularly and linearly polarized AC magnetic fields. Using the exact analytical solutions, we can confirm the insight that underlies Rosensweig’s introduction of the “chord” susceptibility for an approximate calculation of the losses. As an important consequence, it can also explain experiments, where power dissipation for both fields was found to be identical in “root mean square” sense. We also find that this approximation provides satisfactory numerical accuracy only up to magnetic fields for which the argument of the Langevin function reaches the value 2.8.

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Lux, A., and M. Stockhausen. "Variation of the Dielectric Relaxation Behaviour of Water by Added Alcohols." Zeitschrift für Naturforschung A 45, no. 8 (August 1, 1990): 995–98. http://dx.doi.org/10.1515/zna-1990-0809.

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AbstractThe dielectric relaxation of water rich aqueous solutions of ethanol, ehtylene glycol, glycerol, diethylene glycol, 1,2-butanediol, 1,3-butanediol and 1,4-butanediol has been measured at 20 °C. In all cases the fitting of the data by a sum of Debye type spectral components allows for two description modes which can be interpreted as a collective alteration of the water relaxation or, on the other hand, as formation of a microheterogenous solution where "affected" and "unaffected" water becomes discernible

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13

Eid, M. A. M., I. K. Hakim, K. N. Abd-El-Nour, A. L. G. Saad, and M. Stockhausen. "Dielectric Behaviour of Some Pure Normal Alcohols and their Binary Mixtures." Zeitschrift für Naturforschung A 53, no. 10-11 (November 1, 1998): 809–12. http://dx.doi.org/10.1515/zna-1998-10-1101.

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Abstract The pure 1-alkanols C4 to C12 and seven of their short/long chain binary equimolar mixtures are in-vestigated by static and dynamic dielectric measurements up to 36 GHz at 20, 30 and 40 °C. The apparent dipole moment and the relaxation parameters from a three Debye term analysis of the spectra are discussed. The mixtures are found to behave like a one component alcohol of mean chain length. An odd-even effect is revealed by comparison of mixtures containing C11 with those containing C12 as long chain mixture component.

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14

Badapanda, Tanmaya, Ranjan Harichandan, Sudhasu Nayak, Avinna Mishra, and Sahid Anwar. "Frequency and temperature dependence behaviour of impedance, modulus and conductivity of BaBi4Ti4O15 aurivillius ceramic." Processing and Application of Ceramics 8, no. 3 (2014): 145–53. http://dx.doi.org/10.2298/pac1403145b.

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In this work, we report the dielectric, impedance, modulus and conductivity study of BaBi4Ti4O15 ceramic synthesized by solid state reaction. X-ray diffraction (XRD) pattern showed orthorhombic structure with space group A21am confirming it to be an m=4 member of the Aurivillius oxide. The frequency dependence dielectric study shows that the value of dielectric constant is high at lower frequencies and decreases with increase in frequency. Impedance spectroscopy analyses reveal a non-Debye relaxation phenomenon since relaxation frequency moves towards the positive side with increase in temperature. The shift in impedance peaks towards higher frequency side indicates conduction in material and favouring of the long rangemotion of mobile charge carriers. The Nyquist plot from complex impedance spectrum shows only one semicircular arc representing the grain effect in the electrical conduction. The modulus mechanism indicates the non-Debye type of conductivity relaxation in the material, which is supported by impedance data. Relaxation times extracted using imaginary part of complex impedance (Z??) and modulus (M??) were also found to follow Arrhenius law. The frequency dependent AC conductivity at different temperatures indicates that the conduction process is thermally activated. The variation of DC conductivity exhibits a negative temperature coefficient of resistance behaviour.

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15

DEUTSCH, CLAUDE, GUENTER ZWICKNAGEL, and ANTOINE BRET. "Ultra-cold plasmas: a paradigm for strongly coupled and classical electron fluids." Journal of Plasma Physics 75, no. 6 (April 15, 2009): 799–815. http://dx.doi.org/10.1017/s0022377809007934.

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AbstractUltra-cold plasmas obtained by ionization of atomic Rydberg states are qualified as classical and strongly coupled electron fluids. They are shown to share several common trends with ultra-cold electron flows used for ion-beam cooling. They exhibit specific stopping behaviour to charged particle beams, which may be used for diagnostic purposes. Ultra-cold plasmas are easily strongly magnetized. Then, one expects a strongly anisotropic behaviour of low ion velocity slowing down when the target electron cyclotron radius becomes smaller than the corresponding Debye length.

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Demetrius, Lloyd, and J. A. Tuszynski. "Quantum metabolism explains the allometric scaling of metabolic rates." Journal of The Royal Society Interface 7, no. 44 (September 4, 2009): 507–14. http://dx.doi.org/10.1098/rsif.2009.0310.

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A general model explaining the origin of allometric laws of physiology is proposed based on coupled energy-transducing oscillator networks embedded in a physical d -dimensional space ( d = 1, 2, 3). This approach integrates Mitchell's theory of chemi-osmosis with the Debye model of the thermal properties of solids. We derive a scaling rule that relates the energy generated by redox reactions in cells, the dimensionality of the physical space and the mean cycle time. Two major regimes are found corresponding to classical and quantum behaviour. The classical behaviour leads to allometric isometry while the quantum regime leads to scaling laws relating metabolic rate and body size that cover a broad range of exponents that depend on dimensionality and specific parameter values. The regimes are consistent with a range of behaviours encountered in micelles, plants and animals and provide a conceptual framework for a theory of the metabolic function of living systems.

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17

Swaminathan, V., V. P. Panov, S. P. Sreenilayam, Yu P. Panarin, and J. K. Vij. "A modified Langevin-Debye model for investigating the electro-optic behaviour of de Vries smectic liquid crystals." Liquid Crystals 46, no. 8 (December 10, 2018): 1246–51. http://dx.doi.org/10.1080/02678292.2018.1549280.

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18

Mazuki, Nor Fatihah, Pramod Kumar Singh, and Ahmad Salihin Samsudin. "Study on Electrical Conduction Properties of Plasticized CMC-DTAB Based Solid Biopolymer Electrolytes." Materials Science Forum 1025 (March 2021): 15–19. http://dx.doi.org/10.4028/www.scientific.net/msf.1025.15.

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This work focuses on the electrical properties study of solid biopolymer electrolyte (SBE) based plasticized carboxy methylcellulose (CMC) doped dodecyltrimethyl ammonium bromide (DTAB). Different weight percentage of ethylene carbonate (EC) which acts as plasticizer was incorporated into SBE system and were successfully prepared via solution casting technique. The conduction properties of SBE was investigated by using electrical impedance spectroscopy (EIS). The incorporation of 10 wt.% EC was found to achieve the highest ionic conductivity with 1.00 10-3 S cm-1 at room temperature. All SBE samples shows the ionic conductivity increased proportionally with temperature thus obeys to Arrhenius behaviour with regression value almost close to unity (R2~1). The electrical conduction behaviour of the CMC-DTAB-EC SBE reveals non-Debye behaviour without single relaxation properties.

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Świątek-Tran, B., H. A. Kołodziej (deceased), A. Vogt, and V. H. Tran. "Dielectric properties of Co(CO3)(H2O)2(C3H4N2)2 and [Co(C3H3N2)2]n." RSC Advances 5, no. 13 (2015): 9539–45. http://dx.doi.org/10.1039/c4ra13950j.

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Dielectric relaxation phenomenon with non-Debye dynamics in Co(CO₃)(H₂O)₂(C₃H₄N₂)₂ and [Co(C₃H₃N₂)₂]_n, resembling the behaviour of ferroelectric relaxors is presumably connected with the charge carriers.

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20

Koo, Yo-Han, and Young-Dae Jung. "Oscillatory Screening Effects on Elastic Collisions in Dense Electron-Ion Quantum Plasmas." Zeitschrift für Naturforschung A 64, no. 3-4 (April 1, 2009): 237–41. http://dx.doi.org/10.1515/zna-2009-3-411.

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Abstract The oscillatory screening effects on elastic electron-ion collisions are investigated in dense quantum plasmas. The eikonal method with the modified Debye-Hückel potential is employed to obtain the scattering phase shift and scattering amplitude. In addition, the total elastic collision cross section is obtained by the optical theorem with the forward scattering amplitude in quantum plasmas. It is shown that the modified Debye-Hückel screening in quantum plasmas produces the oscillatory behaviour of the scattering phase shift. In addition, the minimum position of the phase shift is receded from the target ion with decreasing the quantum wave number. It is also found that the oscillatory screening effect suppresses the differential cross section. The total cross section is also found to be decreased due to the oscillatory screening effect. In addition, it is shown that the total cross section decreases with an increase of the quantum wave number

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21

Golovko, M. F., and L. A. Protsykevych. "Solutions of Sodium in Liquid Ammonia as Described by a Hard Sphere Charge-Dipole Model in the Neutralizing Background." Zeitschrift für Naturforschung A 46, no. 1-2 (February 1, 1991): 19–26. http://dx.doi.org/10.1515/zna-1991-1-204.

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AbstractThe analytic solution of the mean spherical approximation obtained by us previously for the ion-dipole system in a neutralizing background is applied to study the structural, thermodynamic and dielectric properties of sodium-ammonia solutions. It is shown that the structure of ammonia is closepacked and changes little with ion concentration. The shape of the ion-ion distribution function changes from solvation behaviour with Debye-like asymptotics at low ion concentration to density ordering in the metalic region.

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Deprince, J., S. Fritzsche, T. R. Kallman, P. Palmeri, and P. Quinet. "Influence of plasma environment on K-line emission in highly ionized iron atoms evaluated using a Debye–Hückel model." Canadian Journal of Physics 95, no. 9 (September 2017): 858–61. http://dx.doi.org/10.1139/cjp-2016-0667.

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The influence of plasma environment on the atomic parameters associated with the K-vacancy states has been investigated theoretically for several iron ions. To do this, a time-averaged Debye–Hückel potential for both the electron–nucleus and electron–electron interactions has been considered in the framework of relativistic multiconfiguration Dirac–Fock computations. More particularly, the plasma screening effects on ionization potentials, K-thresholds, transition energies, and radiative rates have been estimated in the astrophysical context of accretion disks around black holes. In the present paper, we describe the behaviour of those atomic parameters for Ne-, Na-, Ar-, and K-like iron ions.

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23

Isa, M. I. N., and Noor Azniza Mohd Noor. "Ionic Conduction Mechanism of Solid Biodegradable Polymer Electrolytes Based Carboxymethyl Cellulose Doped Ammonium Thiocyanate." Applied Mechanics and Materials 719-720 (January 2015): 114–18. http://dx.doi.org/10.4028/www.scientific.net/amm.719-720.114.

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A conducting solid biodegradable polymer electrolytes based carboxymethyl cellulose (CMC) doped ammonium thiocyanate (NH4SCN) system with concentration in the range 0 – 25 wt.% of NH4SCN have been prepared via solution casting method. The impedance study of CMC-NH4SCN system was measured via Electrical Impedance Spectroscopy (EIS) in the temperature range 303 K – 353 K. The highest ionic conductivity at room temperature (303 K) is 6.48 x 10-5Scm-1for sample containing 25 wt.% NH4SCN. The temperature dependence of CMC-NH4SCN system was found to obey the Arrhenius behaviour where the ionic conductivity increases with increase of temperature. Dielectric data were analyzed using complex permittivity, Ɛifor sample with the highest ionic conductivity at various temperatures and found was non Debye behavior. The conduction mechanism of the charge carrier of CMC-NH4SCN system can be presented by quantum mechanical tunneling (QMT) model.

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Saddeek, Yasser B., and N. Z. Elsayed. "Structural and mechanical features of some lanthanum tellurite glasses." Canadian Journal of Physics 93, no. 4 (April 2015): 460–65. http://dx.doi.org/10.1139/cjp-2014-0044.

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Tellurite-based glasses of the chemical formula xLa2O3-(100 – x) TeO2, (2.5 ≤ x ≤ 12.5 mol%) have been prepared and studied by FTIR spectroscopy and the ultrasonic technique. The FTIR analysis indicated that La2O3 transformed the TeO3 into TeO4 structural units in the range 2.5 ≤ x ≤ 5, while in the range 5 ≤ x ≤ 7.5 mol%; there is a coordination transformation of Te atoms in [TeO4] groups into [Formula: see text] groups associated with the formation of non-bridging oxygens. Beyond x = 7.5 mol%, the structural units [Formula: see text] (tp) were destroyed and transformed into TeO4 structural units that acted as a former and tightened the tellurite glass network more. The stretching force constant of the tellurite structural units was affected with the increase of La2O3 content. The structural variations of the structural units of TeO2 and La2O3 affected the increase of density, the behaviour of the ultrasonic velocities, the elastic moduli, and both of the optical and acoustical Debye temperature with increasing La2O3 content. The ratio of optical to acoustic Debye temperature represented the three-dimensional nature of tellurite-based glasses.

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Mahal, Harpreet Singh, Bhanu Partap Singh, and Ravi Kant. "The Effect of Co doping on Structural, Optical and Dielectric Behaviour of TiO2 Nanoparticles." Defence Science Journal 71, no. 03 (May 17, 2021): 390–94. http://dx.doi.org/10.14429/dsj.71.16720.

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Chemical precipitation method was used to synthesise pure and Co-doped TiO2 nanoparticles. The synthesised nanoparticles were studied for its structural optical and dielectric properties. X-Ray diffraction (XRD) confirmed the anatase phase with the tetragonal structure obtained for both samples. No extra peak was obtained in the pattern indicates that cobalt ions were successfully incorporated. The crystallite size of both samples were determined by using Debye-Scherrer’s method, and it was found that it decreases with the dopant addition. UV vis spectroscopy was performed to study the optical properties of both samples. The dielectric constant (εʹ), dielectric loss and ac conductivity (σac) of both samples were studied against the frequency. The dielectric constant, dielectric loss and ac conductivity results showed that Co-doping has a significant effect.

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LOS, J., T. JANSSEN, and F. GÄHLER. "THE PHONON SPECTRUM OF THE OCTAGONAL TILING." International Journal of Modern Physics B 07, no. 06n07 (March 1993): 1505–25. http://dx.doi.org/10.1142/s0217979293002468.

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A study of the phonon spectrum of the octagonal tiling is presented, by calculating and analysing the properties of the spectrum of perfect and randomized commensurate approximants with unit cells containing up to 8119 vertices. The total density of states, obtained by numerical integration over the Brillouin zone, exhibits much structure, and in the low frequency range of the spectrum there is deviation from the normal linear behaviour in the form of pseudogaps. For randomized approximants these pseudogaps disappear and the density of states is globally smoothened. It turns out that the widths of the gaps in the dispersion vanish in the low frequency limit. Therefore the scaling behaviour of the lowest branches tends to the behaviour of an absolutely continuous spectrum, which is not the case at higher frequencies. As an application, the vibrational specific heat of the different tiling models is calculated and compared to the specific heat of a square lattice and of a Debye model.

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Gusev, Yuri Vladimirovich. "The quasi-low temperature behaviour of specific heat." Royal Society Open Science 6, no. 1 (January 2019): 171285. http://dx.doi.org/10.1098/rsos.171285.

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A new mathematical approach to condensed matter physics, based on the finite temperature field theory, was recently proposed. The field theory is a scale-free formalism; thus, it denies absolute values of thermodynamic temperature and uses dimensionless thermal variables, which are obtained with the group velocities of sound and the interatomic distance. This formalism was previously applied to the specific heat of condensed matter and predicted its fourth power of temperature behaviour at sufficiently low temperatures, which was tested by experimental data for diamond lattice materials. The range of temperatures with the quartic law varies for different materials; therefore, it is called the quasi-low temperature regime. The quasi-low temperature behaviour of specific heat is verified here with experimental data for the fcc lattice materials, silver chloride and lithium iodide. The conjecture that the fourth order behaviour is universal for all condensed matter systems has also supported the data for glassy matter: vitreous silica. This law is long known to hold for the bcc solid helium-4. The characteristic temperatures of the threshold of the quasi-low temperature regime are found for the studied materials. The scaling in the specific heat of condensed matter is expressed by the dimensionless parameter, which is explored with the data for several glasses. The explanation of the correlation of the ‘boson peak’ temperature with the shear velocity is proposed. The critique of the Debye theory of specific heat and the Born–von Karman model of the lattice dynamics is given.

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Subashini, C., R. Ezhil Pavai, and L. Balu. "Effect of Pb2+ Ions on the Mechanical, Structural and Thermal Behaviour of B2O3-CaO Glasses." Asian Journal of Chemistry 32, no. 1 (November 18, 2019): 101–5. http://dx.doi.org/10.14233/ajchem.2020.22337.

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B2O3-CaO-PbO glasses with different concentrations of PbO (5-20 mol % in four steps) were prepared by melt quench technique. The amorphous nature and homogeneities of the prepared glasses were confirmed by XRD and SEM analyses. Ultrasonic velocities and density were measured at 303 K using pulse-echo technique and Archimedes’ principle respectively. Various parameters, viz., molar volume, longitudinal modulus, shear modulus, bulk modulus, Young’s modulus, Poisson’s ratio, micro-hardness and Debye temperature have been evaluated from the measured data. The results of ultrasonic properties indicate that the incorporation of lead ions expand the calcium borate network structure. FTIR spectra revealed that boron exists in both trigonal and tetrahedral structural units and no boroxial ring formation takes place in the glass structure. The transition temperature, melting temperature and crystallization temperature have been identified using DTA measurements.

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Jiang, Hua-Long, Song-Hao Jia, Da-Wei Zhou, Chun-Ying Pu, Fei-Wu Zhang, and Shuai Zhang. "First-Principles Calculations of the Mechanical and Elastic Properties of 2Hc- and 2Ha-WS2/CrS2 Under Pressure." Zeitschrift für Naturforschung A 71, no. 6 (June 1, 2016): 517–24. http://dx.doi.org/10.1515/zna-2015-0517.

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AbstractBy utilizing the first-principles method, the pressure-induced effects on phase transition, mechanical stability, and elastic properties of WS2/CrS2 are investigated in the pressure range from 0 to 80 GPa. Transitions from 2Hc to 2Ha for WS2 and CrS2 are found to occur at 17.5 and 25 GPa, respectively. It is found that both 2Ha and 2Hc phases of WS2 and CrS2 meet the mechanical stability criteria up to 80 GPa, suggesting that those structures are mechanically stable. The bulk and shear modulus anisotropy of the two phases of WS2 and CrS2 decrease rapidly under pressure and, finally, trend to isotropy. With increasing pressure, the elastic moduli (Y, B, and G), sound velocities (vs, vp, vm), and Debye temperatures (Θ) of 2Ha and 2Hc of WS2 and CrS2 increase monotonously. Moreover, the Debye temperature (Θ) of 2Hc phase is higher than that of 2Ha phase for both WS2 and CrS2. The bulk, shear, and Young’s modulus, Poisson coefficient, and brittle/ductile behaviour are estimated. The percentages of anisotropy in compressibility and shear and the ratio of bulk to shear modulus (B/G) are also studied.

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Saad, A., U. Becker, M. Stockhausen, and Y. Barakat. "Notiz: Dynamic Dielectric Properties of Some Alkylamino Ethoxylates." Zeitschrift für Naturforschung A 50, no. 11 (November 1, 1995): 1083–84. http://dx.doi.org/10.1515/zna-1995-1116.

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Abstract Nine ethoxylated (EO) alkyl amines, (CnH2n + 1) N(EO)x; H(EO)y H, with n = 10 to 16 and p = x + y = 7.6 to 14.5, were studied as pure liquids with respect to their dielectric relax ation behaviour over the frequency range 5 MHz to 36 GHz at 20 °C. The broad and structureless dielectric loss spectrum is similar for all samples. It can be described by a main lower frequency spectral component of Havriliak-Negami type plus two minor, higher frequency Debye type components. The relaxation parameters are reported. Dynamic Dielectric Properties of Some Alkylamino Ethoxylates

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Vinay, K., K. Shivakumar, Y. T Ravikiran, and M. Revanasiddappa. "Spectroscopic Studies, Thermal Behaviour and Ac Impedance Study of Chemically Synthesized Silver Doped Polyaniline / BaFe12O19 Polymer Composite." International Journal of Engineering & Technology 7, no. 4.5 (September 22, 2018): 20. http://dx.doi.org/10.14419/ijet.v7i4.5.20001.

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The present work is a study of a.c impedance response and thermal behaviour of IPANI/Ag/BaFe12O19 (PAB) composites synthesized by in-situ oxidative interfacial polymerization using (NH4)2S2O8 as an oxidizing agent at 0-50C. The synthesized polymer compo- sites were examined by FT-IR, TGA-DTA and DSC techniques. The a.c conductivity properties of the composites were investigated in the frequency range varying from 5x101 – 5x106 Hz at room temperature using HIOKI make 3532-50 LCR Hi-tester. FT-IR profiles confirm the formation of ferrite composite. The endothermic regions in the DTA pattern are consistent with the change regions in the TG curve. The Cole-Cole plots observed in the form of exact semi-circles clearly suggests the Debye-type relaxation mechanism present in these materials.

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Noor, N. A. M., and M. I. N. Isa. "Ionic Conductivity and Dielectric Properties of CMC Doped NH₄SCN Solid Biopolymer Electrolytes." Advanced Materials Research 1107 (June 2015): 230–35. http://dx.doi.org/10.4028/www.scientific.net/amr.1107.230.

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In this work, solid biopolymer electrolytes (SBE) containing carboxymethyl cellulose (CMC) doped with ammonium thiocyanate (NH4SCN) were prepared via solution casting method. The ionic conductivity and dielectric properties of CMC-NH4SCN system were investigated by electrical impedance spectroscopy in the temperature range of 303-353 K. The dc conductivity shows that the highest ionic conductivity of 6.48 x 10-5 Scm-1 at ambient temperature was obtained when 25 wt.% of NH4SCN was incorporated. The temperature dependence of ionic conductivity revealed that CMC-NH4SCN system was discovered to obey Arrhenius law where the regression value is almost unity (R2≈1). Activation energy of CMC-NH4SCN system was found to decrease with the increment of NH4SCN concentration. The dielectric behaviour of the CMC-NH4SCN system have been analyzed using dielectric permittivity (ε*) and electrical modulus (M*) spectra. Results from dielectric studies showed a non-Debye behaviour of CMC-NH4SCN system.

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CONROY, D. T., R. V. CRASTER, O. K. MATAR, and D. T. PAPAGEORGIOU. "Dynamics and stability of an annular electrolyte film." Journal of Fluid Mechanics 656 (May 26, 2010): 481–506. http://dx.doi.org/10.1017/s0022112010001254.

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We investigate the evolution of an electrolyte film surrounding a second electrolyte core fluid inside a uniform cylindrical tube and in a core-annular arrangement, when electrostatic and electrokinetic effects are present. The limiting case when the core fluid electrolyte is a perfect conductor is examined. We analyse asymptotically the thin annulus limit to derive a nonlinear evolution equation for the interfacial position, which accounts for electrostatic and electrokinetic effects and is valid for small Debye lengths that scale with the film thickness, that is, charge separation takes place over a distance that scales with the annular layer thickness. The equation is derived and studied in the Debye-Hückel limit (valid for small potentials) as well as the fully nonlinear Poisson–Boltzmann equation. These equations are characterized by an electric capillary number, a dimensionless scaled inverse Debye length and a ratio of interface to wall electrostatic potentials. We explore the effect of electrokinetics on the interfacial dynamics using a linear stability analysis and perform extensive numerical simulations of the initial value problem under periodic boundary conditions. An allied nonlinear analysis is carried out to investigate fully singular finite-time rupture events that can take place. Depending upon the parameter regime, the electrokinetics either stabilize or destabilize the film and, in the latter case, cause the film to rupture in finite time. In this case, the final film shape can have a ring- or line-like rupture; the rupture dynamics are found to be self-similar. In contrast, in the absence of electrostatic effects, the film does not rupture in finite time but instead evolves to very long-lived quasi-static structures that are interrupted by an abrupt re-distribution of these very slowly evolving drops and lobes. The present study shows that electrokinetic effects can be tuned to rupture the film in finite time and the time to rupture can be controlled by varying the system parameters. Some intriguing and novel behaviour is also discovered in the limit of large scaled inverse Debye lengths, namely stable and smooth non-uniform steady state film shapes emerge as a result of a balance between destabilizing capillary forces and stabilizing electrokinetic forces.

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34

Kaiser, AB, AL Christie, and BL Gallagher. "Investigation of the Interaction of Electrons and Lattice Vibrations Using Glassy Metal Thermopower." Australian Journal of Physics 39, no. 6 (1986): 909. http://dx.doi.org/10.1071/ph860909.

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We calculate the electron-phonon enhancement effect in thermopower using several different models for the Eliashberg function a2 F(E) which describes the interaction of electrons and lattice vibrations. The behaviour of a 2 F(E) at low energies determines whether the predicted thermopower enhancement shows a peak at low temperatures, but the enhancement is rather insensitive to the detailed spectral shape of a2 F(E) at higher energies. The calculations are able to give a good account of the thermopowers of several glassy metals measured by Gallagher and Hickey (1985), with slightly better agreement obtained for a smooth rather than a Debye-like a2 F(E).

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35

Prado, Pablo J., Robin L. Armstrong, and Brian Powell. "Influence of substitutional impurities on the static and dynamical behaviour of K2OsCl6 in the vicinity of the structural phase transition: A neutron diffraction study." Canadian Journal of Physics 73, no. 9-10 (September 1, 1995): 626–31. http://dx.doi.org/10.1139/p95-091.

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The effect of IrCl62− and ReCl62− impurity ions substituted for OsCl62− ion in K2OsCl6 is studied using neutron powder diffraction. The introduction of the impurity ions causes measurable changes in the lattice parameters but not in the Os—Cl bond length. The dynamical parameters of the model structure used to fit the data are well described by a Debye model of the lattice vibrations. The structural phase-transition temperature is affected by the addition of the impurity ions. Evidence is provided for suppression, in the presence of the impurities, of the development of precursor dynamical clusters above the phase-transition temperature.

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36

Kamali, R., and M. Eslami. "A numerical investigation of transient electro-osmotic flow in rectangular microchannels: A comparison of different models." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 224, no. 8 (January 12, 2010): 1655–63. http://dx.doi.org/10.1243/09544062jmes2008.

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Transient electro-osmotic flow in rectangular microchannels is investigated numerically in this article. The complete Poisson—Boltzmann equation along with the time-dependent momentum equation is solved using the finite-difference method. Moreover, linearized equations based on the Debye—Huckle assumption are also solved to compare with the available analytical approximate solutions. The effects of different parameters such as wall zeta potential, non-dimensional electrokinetic width, and channel aspect ratio are also studied. It is shown that the Debye—Huckle approximation is not only valid for small values of zeta potential, but also the channel hydraulic diameter should be large enough with respect to electrical double layer (EDL) thickness. In addition, the flow behaviour at higher values of zeta potential is shown to be completely different from what available analytical solutions predict. Effective parameters on the transition period from the start time to the steady-state condition are also discussed. On the other hand, a comparison between the present numerical solution and the results of slip velocity approximation reveals that the slip model could be only used for very large values of non-dimensional electro-kinetic width. Finally, velocity distributions in channels of different aspect ratios are provided and discussed.

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37

Declémy, A., C. Rullière, and Ph Kottis. "Picosecond solvation of electronically excited solutes in alcoholic solvents: non-debye behaviour of the time-dependent fluorescence shift related to h." Chemical Physics Letters 133, no. 5 (January 1987): 448–54. http://dx.doi.org/10.1016/0009-2614(87)87100-2.

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38

Arcos, J. C., F. Méndez, E. G. Bautista, and O. Bautista. "Dispersion coefficient in an electro-osmotic flow of a viscoelastic fluid through a microchannel with a slowly varying wall zeta potential." Journal of Fluid Mechanics 839 (January 29, 2018): 348–86. http://dx.doi.org/10.1017/jfm.2018.11.

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The dispersion coefficient of a passive solute in a steady-state pure electro-osmotic flow (EOF) of a viscoelastic liquid, whose rheological behaviour follows the simplified Phan-Thien–Tanner (sPTT) model, along a parallel flat plate microchannel, is studied. The walls of the microchannel are assumed to have modulated and low $\unicode[STIX]{x1D701}$ potentials, which vary slowly in the axial direction in a sinusoidal manner. The flow field required to obtain the dispersion coefficient was solved using the lubrication approximation theory (LAT). The solution of the electric potential is based on the Debye–Hückel approximation for a symmetric $(z:z)$ electrolyte. The viscoelasticity of the fluid is observed to notably amplify the axial distribution of the effective dispersion coefficients due to the variation in the $\unicode[STIX]{x1D701}$ potentials of the walls. The problem was formulated for two cases: when the Debye layer thickness (EDL) was on the order of unity (thick EDL) and in the limit where the thickness of the EDL was very small compared with the height of the microchannel (thin EDL limit). Due to the coupling between the nonlinear governing equations and the sPTT fluid model, they were replaced by their approximate linearized forms and solved in the limit of $\unicode[STIX]{x1D700}\ll 1$ using the regular perturbation technique. Here $\unicode[STIX]{x1D700}$ is the amplitude of the sinusoidal function of the $\unicode[STIX]{x1D701}$ potentials. Additionally, the numerical solution of the simplified governing equations was also obtained for $\unicode[STIX]{x1D700}=O(1)$ and compared with the approximate solution, showing excellent agreement for $0\leqslant \unicode[STIX]{x1D700}\leqslant 0.3$. Note that the dispersion coefficient primarily depends on the Deborah number, on the ratio of the half-height of the microchannel to the Debye length, and on the assumed variation in the $\unicode[STIX]{x1D701}$ potentials of the walls.

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39

Treumann, Rudolf A., and Wolfgang Baumjohann. "The mirror mode: a “superconducting” space plasma analogue." Annales Geophysicae 36, no. 4 (July 26, 2018): 1015–26. http://dx.doi.org/10.5194/angeo-36-1015-2018.

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Abstract. We examine the physics of the magnetic mirror mode in its final state of saturation, the thermodynamic equilibrium, to demonstrate that the mirror mode is the analogue of a superconducting effect in a classical anisotropic-pressure space plasma. Two different spatial scales are identified which control the behaviour of its evolution. These are the ion inertial scale λim(τ) based on the excess density Nm(τ) generated in the mirror mode, and the Debye scale λD(τ). The Debye length plays the role of the correlation length in superconductivity. Their dependence on the temperature ratio τ=T‖/T⟂<1 is given, with T⟂ the reference temperature at the critical magnetic field. The mirror-mode equilibrium structure under saturation is determined by the Landau–Ginzburg ratio κD=λim/λD, or κρ=λim/ρ, depending on whether the Debye length or the thermal-ion gyroradius ρ – or possibly also an undefined turbulent correlation length ℓturb – serve as correlation lengths. Since in all space plasmas κD≫1, plasmas with λD as the relevant correlation length always behave like type II superconductors, naturally giving rise to chains of local depletions of the magnetic field of the kind observed in the mirror mode. In this way they would provide the plasma with a short-scale magnetic bubble texture. The problem becomes more subtle when ρ is taken as correlation length. In this case the evolution of mirror modes is more restricted. Their existence as chains or trains of larger-scale mirror bubbles implies that another threshold, VA>υ⟂th, is exceeded. Finally, in case the correlation length ℓturb instead results from low-frequency magnetic/magnetohydrodynamic turbulence, the observation of mirror bubbles and the measurement of their spatial scales sets an upper limit on the turbulent correlation length. This might be important in the study of magnetic turbulence in plasmas.

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Das, Rutuparna, and Ram Choudhary. "Structure, dielectric and electrical properties of relaxor lead-free double perovskite: Nd2NiMnO6." Processing and Application of Ceramics 13, no. 1 (2019): 1–11. http://dx.doi.org/10.2298/pac1901001d.

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In this paper, dielectric relaxor, impedance, AC conductivity and electrical modulus of double perovskite Nd2NiMnO6, prepared by a solid state reaction method and sintered at 1250?C, have been reported in the wide temperature (25-150?C) and frequency (1 kHz-1MHz) ranges. From the preliminary X-ray structural analysis, it is found that the structure of the material is monoclinic. In the study of the temperature dependence of the dielectric constant, the relaxor behaviour of the material is observed. Such type of behaviour is explained by a modified Curie-Weiss and a Vogel-Fulcher law. By analysing Nyquist plots, the existence of grain and grain boundary effects is established. The non-Debye type of relaxation is investigated by the analysis of complex impedance and the modulus data. From the study of impedance data, it is found that the grain resistance is reduced with the increase in temperature indicating the existence of negative temperature coefficient of resistance (NTCR) behaviour in the material which also matches with temperature versus AC conductivity plots. From these results, it may be concluded that this compound may have extreme potential for different high temperature applications.

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41

Sabine, TM. "Accurate Structure Factor Measurements by Powder Methods." Australian Journal of Physics 41, no. 3 (1988): 413. http://dx.doi.org/10.1071/ph880413.

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Powder diffraction data are normally analysed by Rietveld refinement. In this technique the observed diffraction. pattern is fitted to a calculated pattern by least-squares methods. The accuracy with which structure factors can be determined is dependent on the parameters in the model being an accurate representation of the physical situation. The Rietveld model is derived in the kinematic approximation. Deviations from kinematic behaviour because of extinction, absorption, thermal diffuse scattering, and multiple scattering are then included in the model. As a test of the method the Debye-Waller factor (which is the only unknown component of the structure factor) is determined for magnesium oxide from time-of-Bight neutron data on four specimens of very different grain size.

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Shukur, M. F., M. F. Z. Kadir, Z. Ahmad, and R. Ithnin. "Dielectric Studies of Proton Conducting Polymer Electrolyte Based on Chitosan/PEO Blend Doped with NH₄NO₃." Advanced Materials Research 488-489 (March 2012): 583–87. http://dx.doi.org/10.4028/www.scientific.net/amr.488-489.583.

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Polymer blend of chitosan and poly(ethylene oxide) (PEO) electrolytes were prepared by employing solution cast method. Ammonium nitrate (NH4NO3) was added to the blend to supply the charge carriers for ionic conduction. The impedance of the electrolytes was measured by electrical impedance spectroscopy (EIS) over the frequency range of 50 Hz to 1 MHz. The permittivity ɛr and electric modulus Mr of the complex were analyzed. Dispersion at low frequencies caused by space charge effect from the electrodes was observed. The modulus plots indicated that the dispersion deviated from the Debye behaviour. The relaxation time, τ decreased to 1.64 × 10-7 s as the NH4NO3 content was increased up to 40 wt.%.

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43

MATEJCZYK, B., J. F. PIETSCHMANN, M. T. WOLFRAM, and G. RICHARDSON. "Asymptotic models for transport in large aspect ratio nanopores." European Journal of Applied Mathematics 30, no. 3 (June 6, 2018): 557–84. http://dx.doi.org/10.1017/s0956792518000293.

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Ion flow in charged nanopores is strongly influenced by the ratio of the Debye length to the pore radius. We investigate the asymptotic behaviour of solutions to the Poisson–Nernst–Planck (PNP) system in narrow pore like geometries and study the influence of the pore geometry and surface charge on ion transport. The physical properties of real pores motivate the investigation of distinguished asymptotic limits, in which either the Debye length and pore radius are comparable or the pore length is very much greater than its radius This results in a quasi-one-dimensional (1D) PNP model, which can be further simplified, in the physically relevant limit of strong pore wall surface charge, to a fully 1D model. Favourable comparison is made to the two-dimensional (2D) PNP equations in typical pore geometries. It is also shown that, for physically realistic parameters, the standard 1D area averaged PNP model for ion flow through a pore is a very poor approximation to the (real) 2D solution to the PNP equations. This leads us to propose that the quasi-1D PNP model derived here, whose computational cost is significantly less than 2D solution of the PNP equations, should replace the use of the 1D area averaged PNP equations as a tool to investigate ion and current flows in ion pores.

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44

Horsák, Ivan, and Ivo Sláma. "A lattice model of electrolytes for the whole concentration range." Collection of Czechoslovak Chemical Communications 52, no. 7 (1987): 1672–79. http://dx.doi.org/10.1135/cccc19871672.

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Based on the quasi-lattice concept, a simple model is proposed for calculating the quantities of mixing of strong electrolyte solutions over the whole concentration range from pure solvent to pure salt. This model is analogous to the regular solution model for non-electrolyte systems. Relationships for the activity coefficients of the solvent and salt have been derived, and the behaviour of the model in the limit of infinite dilution is discussed by comparison with the Debye-Huckel theory. The adequacy of equations derived from the proposed model has been tested by fitting published experimental data for the activities of water in the systems (Li, K)NO3-H2O and (Ag, Tl)NO3-H2O, which have been measured over the whole concentration range.

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45

Jadżyn, J., C. Legrand, P. Kędziora, B. Żywucki, G. Czechowski, and D. Bauman. "Dielectric Behaviour of 1-(4-Isothiocyanatophenyl)-2-(4-hexyl- bicyclo[2,2,2]octane-1)ethane in Nematic and Isotropic Phases." Zeitschrift für Naturforschung A 51, no. 8 (August 1, 1996): 933–38. http://dx.doi.org/10.1515/zna-1996-0808.

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Abstract Static and dynamic investigations of the dielectric properties of the liquid crystal 1-(4-isothio-cyanatophenyl)-2-(4-hexyl-bicyclo[2,2,2]octane-1)ethane in the nematic and isotropic phases have been carried out in the frequency region from 1 kHz to 1 GHz. Two relaxation processes, described by the Debye functions, have been observed not only in the isotropic but also in the nematic phase, when the measurements of the electric permittivity vs. frequency have been made parallel to the orientation axis of liquid crystal. These processes are related to the rotation of the permanent dipole moment around two main molecular axes. The height of the potential barrier which hinders the rotation of the liquid crystal molecule around the short axis in the ordered nematic phase and the order parameter of the liquid crystal investigated have been estimated on the basis of the relaxation time values in the nematic and isotropic phases.

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46

Osman, Rozana A. M., and Mohd Sobri Idris. "Electrical Properties of Fresnoite Ba₂TiSi₂O₈ Using Impedance Spectroscopy." Advanced Materials Research 795 (September 2013): 640–43. http://dx.doi.org/10.4028/www.scientific.net/amr.795.640.

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Fresnoite with composition Ba2TiSi2O8 (B2TS2) was first found in 1965, adopting a non-centrosymmetric structure. It also reported to crystallize in a tetragonal unit cell with a=8.52Å and c=5.210Å leading to some possible application as hydrophone, transducer and second harmonic generation and low temperature co-fired ceramics (LTCC). B2TS2 were synthesized by conventional solid state reaction. Phase pure B2TS2 was obtained after heating the pellets at a final sintering temperature of 1230 °C in air at 92 h. Study found that Fresnoite B2TS2 is a type of materials which are not ferroelectric and instead show perfect dielectric insulator behaviour with resistance >106Ωcm at temperatures below 750°C and also shows nonideal debye respone. The activation energy for conduction of B2TS2 samples is very high, indicating that these materials are highly insulating.

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47

Stark, Andreas, Emanuel Schwaighofer, Svea Mayer, Helmut Clemens, Thomas Lippmann, Lars Lottermoser, Andreas Schreyer, and Florian Pyczak. "In Situ High-Energy XRD Study of the Hot-Deformation Behavior of a Novel γ-TiAl Alloy." MRS Proceedings 1516 (2012): 71–76. http://dx.doi.org/10.1557/opl.2012.1577.

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ABSTRACTThe development of suitable hot-forming processes, e.g. forging, is an important step towards the serial production of TiAl parts. Several microstructure parameters change during hot-forming. However, the underlying mechanisms can normally only be inferred from post process metallographic studies.We used a deformation dilatometer modified for working in the HZG synchrotron beamlines at DESY for hot-deformation experiments. This setup enables the in situ monitoring of the interaction and evolution of microstructure parameters during processing. We observed the evolution of phase fractions, grain size and crystallographic texture during deformation while simultaneously recording the process parameters, like temperature, force and length change.Here we present the hot compressive deformation behaviour of a Ti-43Al-4Nb-1Mo-0.1B (in at.%) alloy. Several specimens were deformed at three temperatures each with two compression rates. During the experiments the Debye-Scherrer diffraction rings were continuously recorded.

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48

Patel, Satyanarayan, and Harekrishna Yadav. "Electrical conduction properties of the BZT–BST ceramics." Journal of Advanced Dielectrics 10, no. 06 (December 2020): 2050026. http://dx.doi.org/10.1142/s2010135x20500265.

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0.5Ba([Formula: see text][Formula: see text]O3-0.5([Formula: see text][Formula: see text]TiO3 (BZT–BST) has been explored in recent times for potential applications in energy harvesting, electrocaloric and energy storage. To this end, energy harvesting/conversion and storage applications require an understanding of the conduction and loss mechanisms. The conduction mechanism in BZT–BST ceramics is studied using impedance spectroscopy (IS) at 0.1 Hz−3 MHz and 100−600[Formula: see text]C. Impedance study reveals the presence of two types of relaxation processes due to grain and grain boundary contributions. The relaxation time and dc conductivity activation energies are obtained as 1.12/1.3 eV and 1.05/1.2eV for bulk/grain boundary, respectively, and found that oxygen vacancies dominated electrical behavior. The relaxation mechanism follows non-Debye-type behavior. The high resistance of the grain (bulk) in the ferroelectric region does not contribute to the high losses; the losses probably result from the phase transition. Also, BZT–BST ceramics exhibit a negative temperature coefficient of resistance (NTCR) behaviour. From a practical application point of view in the temperature regime of 25–65[Formula: see text]C, the loss’s contribution is low. The significant contributions of loss result from the response of phase-transition in this temperature range (25–65[Formula: see text]C).

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Madan, M. P. "Dielectric relaxation of nitromethane, some nitriles, and their mixtures in dilute solutions." Canadian Journal of Physics 65, no. 12 (December 1, 1987): 1573–76. http://dx.doi.org/10.1139/p87-260.

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The dielectric absorption of nitromethane, benzonitrile, and acetonitrile and their binary mixtures has been studied in the microwave region over a range of temperatures in dilute benzene solutions. The data on static and optical permittivities at 20 °C have also been obtained, from measurements at 100 kHz and from measuring the refractive index for sodium-D lines, for a few cases. These data have been used to determine the relaxation times and the thermodynamic parameters for the activated state. The results obtained have been discussed in terms of the molecular motion of the systems. A new empirical relation has been proposed to represent the relaxation behaviour of a system of two Debye-type polar components in a nonpolar solvent. The relation has been tested, along with a previously suggested relation, by comparing the calculated values with those determined experimentally.

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50

Dachwitz, E. "Studies of Polymer Solvation by Dielectric Relaxation Spectroscopy III: Polyvinyl Pyrrolidone in N-Methyl-2-Pyrrolidone, Ethanediol, Methanol, and Water." Zeitschrift für Naturforschung A 45, no. 2 (February 1, 1990): 126–34. http://dx.doi.org/10.1515/zna-1990-0207.

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AbstractThe permittivity of the title solutions has been measured at frequencies between some MHz and 72 GHz at 20 °C. Polyvinyl pyrrolidone of relative molar mass ranging from 1200 to 360 000 has been used. Referring to the concentration of monomeric repeat units (x = 0.65 maximum) there is no significant chain length effect. The permittivity data are described in terms of discrete Debye type spectral components. Special attention is paid to the contributions ascribable to the solvents, which are discussed with respect to their solvation behaviour. This can be described by a three state solvent model as follows. Besides the "bulk" solvent a further contribution is found in any case which is due to loosely affected (slowed down) solvent. Moreover a part of the solvent appears to be tightly bound to the polymer at high concentrations. All the solvents considered show similar solvation properties, notwithstanding their different tendencies towards selfassociation.

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Journal articles on the topic 'Debye behaviour'

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