Calculation Of The Damping Constant (Fwhm), The Relaxation Time, And The Activation Energy As A Function Of Temperature For Dmacd(N3)3

The diffusion of fluorine in KSn2F5 has been studied by T1 and T2 relaxation time measurements of 19F NMR (200-500 K) and pulsed magnetic Field gradient techniques (390-480 K). Near 423 K a sharp transition into the superionic state has been found, the fluorine diffusion increasing by a factor of 4 within a range of 3 K. Conductivity measurements only show a change in the activation energy.

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Ionic Motion and Structure of Ion Conductive Glasses

MRS Proceedings ◽

10.1557/proc-321-191 ◽

1993 ◽

Vol 321 ◽

Cited By ~ 3

Author(s):

T. Akai ◽

M. Yamashita ◽

H. Yamanaka ◽

H. Wakabayashi

Keyword(s):

Activation Energy ◽

Relaxation Time ◽

Slow Motion ◽

Lattice Relaxation ◽

Lattice Relaxation Time ◽

Spin Lattice Relaxation ◽

Local Motion ◽

Spin Lattice Relaxation Time ◽

Spin Lattice ◽

Two Samples

ABSTRACTThe dynamic structure of xLi2S-Ga2S3-6GeS2 (x=4 and 6) glasses has been investigated by 7Li nuclear magnetic resonance. In two samples similar values of spin-lattice relaxation time (T1) were obtained. The relaxation mechanism at 20MHz and 78MHz is therefore attributed to the local motion of lithium ions. In the glass corresponding to x=6, which shows higher conductivity, the slow motion of ions showing an activation energy of 24.3kJ/Mol has been detected by the spin-lattice relaxation time in the rotating frame (T1p). This value is comparable to the activation energy determined by the conductivity. The existence of this mode is supported by the motional narrowing of the line width which is sensitive to the motion less than 10kHz.

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Dielectric Properties of Rhombohedral PbNb2O6

Journal of Solid State Physics ◽

10.1155/2013/451563 ◽

2013 ◽

Vol 2013 ◽

pp. 1-9 ◽

Cited By ~ 7

Author(s):

Kriti Ranjan Sahu ◽

Udayan De

Keyword(s):

Activation Energy ◽

Relaxation Time ◽

High Temperature ◽

Single Phase ◽

Rhombohedral Phase ◽

Orthorhombic Phase ◽

Dielectric Materials ◽

Rietveld Analysis ◽

Bulk Resistance ◽

Relaxation Time Constant

Dielectric materials are needed in many electrical and electronic applications. So, basic characterizations need to be done for all dielectrics. PbNb2O6 (PN) is ferroelectric and piezoelectric only in its orthorhombic phase, with potential high temperature applications. So, its rhombohedral phase, frequently formed as an undesirable impurity in the preparation of orthorhombic PN, has been ignored with respect to possible dielectric characterizations. Here, essentially single phase rhombohedral PN has been prepared, checking structure from XRD Rietveld Analysis, and the real and imaginary parts of permittivity measured in an Impedance Spectrometer (IS) up to ~700∘C and over 20 Hz to 5.5 MHz range, for heating and some cooling runs. Variations, with temperature, of relaxation time constant (τ), AC and DC conductivity, bulk resistance, activation energy and capacitance have been explored from our IS data.

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Anelastic Phenomena at the Fibre-Matrix Interface of the Ti6Al4V-SiCf Composite

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.425.263 ◽

2010 ◽

Vol 425 ◽

pp. 263-270 ◽

Cited By ~ 3

Author(s):

Paolo Deodati ◽

Riccardo Donnini ◽

Saulius Kaciulis ◽

Alessio Mezzi ◽

Roberto Montanari ◽

...

Keyword(s):

Activation Energy ◽

Relaxation Time ◽

Photoelectron Spectroscopy ◽

Chemical Characterization ◽

Matrix Interface ◽

Ion Sputtering ◽

Mechanical Spectroscopy ◽

Monolithic Alloy ◽

X Ray ◽

Fibre Matrix

The composite, consisting of Ti6Al4V matrix reinforced by unidirectional SiC fibres (SCS-6), has been investigated by mechanical spectroscopy at temperatures up to 1,173 K. For comparison, the same experiments have been performed on the corresponding monolithic alloy. The internal friction (IF) spectrum of the composite exhibits a new relaxation peak superimposed to an exponentially increasing background. This peak, which is not present in the monolithic alloy, has an activation energy H = 186 kJ mol-1 and a relaxation time 0 = 2.3 x 10-15 s. The phenomenon has been attributed to a reorientation of interstitial-substitutional pairs in the  phase of Ti6Al4V matrix around the fibres. This explanation is supported by the results of micro-chemical characterization carried out by X-ray photoelectron spectroscopy (XPS) combined with Ar ion sputtering.

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Relaxation Measurements of the Persistent Photoconductivity in Sulfur-Doped a-Si:H.

MRS Proceedings ◽

10.1557/proc-420-611 ◽

1996 ◽

Vol 420 ◽

Cited By ~ 1

Author(s):

D. Quicker ◽

J. Kakalios

Keyword(s):

Activation Energy ◽

Relaxation Time ◽

Sulfur Atom ◽

Hydrogenated Amorphous Silicon ◽

Persistent Photoconductivity ◽

Sulfur Concentration ◽

Illumination Time ◽

Thermally Activated ◽

Relaxation Measurements ◽

Hydrogenated Amorphous

AbstractThe slow relaxation of the persistent photoconductivity (PPC) effect in sulfur-doped hydrogenated amorphous silicon (a-Si:H) has been measured as a function of temperature and illumination time. The relaxation is found to be thermally activated, with an activation energy which varies with sulfur concentration, while illuminating the film for a longer time leads to a longer relaxation time. A correlation is observed between changes of the photoconductivity during illumination and the magnitude of the PPC effect following illumination. These effects are also observed in compensated a-Si:H, suggesting that the mechanism for the PPC effect is the same in both sulfur-doped a-Si:H and compensated a-Si:H. The presence of donor and compensating acceptor states in sulfur-doped a-Si:H could arise from valence alternation pair sulfur atom defects.

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Elastic After-Effect Due to Oxygen Relaxation in Yba2Cu3O7−δAbove Tc

MRS Proceedings ◽

10.1557/proc-209-819 ◽

1990 ◽

Vol 209 ◽

Cited By ~ 1

Author(s):

J. R. Cost ◽

P. E. Armstrong ◽

R. B. Poeppel ◽

J. T. Stanley

Keyword(s):

Activation Energy ◽

Relaxation Time ◽

Internal Friction ◽

Relaxation Times ◽

Tracer Diffusion ◽

Induced Motion ◽

Arrhenius Temperature Dependence ◽

After Effect ◽

Friction Measurements ◽

Arrhenius Temperature

ABSTRACTIsothermal elastic after-effect measurements to obtain relaxation times for the stress-induced motion of oxygen in YBa2Cu3O7−δ have been made from 50°C to 110°C. These results extend our previous internal friction measurements of the same oxygen relaxation to lower temperatures. The combined results, which cover nine orders of magnitude in relaxation time, show a classical Arrhenius temperature dependence, activation energy Q−1.13±0.01 eV and attempt frequency τ0−1.6×10−13 s (log τ0−.12.79±0.13). The mechanism of the relaxation is considered to be stress-induced ordering of oxygen atoms on theCuO basal plane. Diffusivities obtained from these results are compared with those from tracer diffusion of oxygen.

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Glass transformation in vitreous As2Se3 studied by conventional and temperature-modulated differential scanning calorimetry

Journal of Materials Research ◽

10.1557/jmr.2001.0329 ◽

2001 ◽

Vol 16 (8) ◽

pp. 2399-2407 ◽

Cited By ~ 12

Author(s):

S. O. Kasap ◽

D. Tonchev

Keyword(s):

Activation Energy ◽

Differential Scanning Calorimetry ◽

Relaxation Time ◽

Glass Transition ◽

Activation Energies ◽

Temperature Modulation ◽

Glass Transition Region ◽

Scanning Calorimetry ◽

Modulated Differential Scanning Calorimetry ◽

Apparent Activation Energies

We have studied the glass transition behavior of vitreous As2Se3 by carrying out temperature-modulated differential scanning calorimetry (TMDSC) and conventional differential scanning calorimetry (DSC) experiments to measure the glass transition temperature Tg. In TMDSC experiments we have examined the reversing heat flow (RHF), that is the complex heat capacity CP in the glass transition region as the glass is cooled from a temperature above the glass transition temperature (from a liquidlike state) and also as the glass is heated starting from room temperature (from a solidlike state). The RHF, or CP versus T, in TMDSC changes sigmoidally through the glass transition region without evincing an enthalpic peak which is one of its distinct advantages for studying the glass transformations. The Tg measurements by TMDSC were unaffected by the amplitude of the temperature modulation. We have determined apparent activation energies by using Tg-shift methods based on the Tg-shift with the frequency (ω) of temperature modulation in the TMDSC mode and Tg-shift with heating and cooling rates, r and q, respectively, in the DSC mode. It is shown that the apparent activation energies ∆h* obtained from ln ω versus 1/Tg and ln q versus 1/Tg plots are not the same, but nonetheless, they are approximately the same as the apparent activation energy ∆hn of the viscosity over the same temperature range where the empirical Vogel expression of Henderson and Ast, η = 12.9 exp[2940/(T - 335)], was used for the viscosity. The latter observation is in agreement with the assertion that the structural relaxation time Ʈ is proportional to the viscosity h. The apparent activation energy ∆hr obtained from the ln r versus 1/Tg plot during heating DSC scans is lower than ∆h* observed during cooling scans. The results are discussed in terms of a phenomenological Narayanaswamy type relaxation time. It was observed that Tg obtained from TMDSC cooling experiments did not depend on the underlying cooling rate for q ≤ 1 °C min-1; and for temperature amplitudes 0.5–5 °C. The transition due to the temperature modulation was well separated from the transition due to the underlying cooling rate. Further, the apparent activation energies obtained from ln ω versus 1/Tg during cooling and heating scans for q and r ≤ 1 °C min−1 are approximately the same as expected from Hutchison's calculations using a single relaxation time model of TMDSC experiments.

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