Probing of structural relaxation times in the glassy state of sucrose and trehalose based on dynamical properties of two secondary relaxation processes

2011 ◽  
Vol 83 (6) ◽  
Author(s):  
K. Kaminski ◽  
K. Adrjanowicz ◽  
E. Kaminska ◽  
M. Paluch
Keyword(s):  
Structural Relaxation ◽  
Glassy State ◽  
Relaxation Times ◽  
Relaxation Processes ◽  
Secondary Relaxation ◽  
Dynamical Properties

Relaxation processes of some simple aliphatic molecules in dilute solutions

1977 ◽  
Vol 55 (4) ◽  
pp. 297-301 ◽  
Author(s):  
M. P. Madan
Keyword(s):  
Carbon Tetrachloride ◽  
Dielectric Relaxation ◽  
Thermodynamic Parameters ◽  
Relaxation Times ◽  
Relaxation Processes ◽  
Dilute Solutions ◽  
Microwave Region ◽  
Nonpolar Solvents ◽  
Dielectric Data ◽  
Intramolecular Rotation

The dielectric relaxation processes of acetone, cyclohexanone, 4-methyl-2-pentanone, and 4-heptanone in dilute nonpolar solvents, n-heptane, cyclohexane, benzene, and carbon tetrachloride have been studied in the microwave region over a temperature range 10 to 60 °C. The relaxation times and the thermodynamic parameters for the activated states have been determined using the measured dielectric data. The results have been discussed in terms of dipole reorientation by molecular and intramolecular rotation and compared, wherever possible, with other similar studies on aliphatic molecules.

Relaxation processes of quinoline, isoquinoline, and their mixtures

1980 ◽  
Vol 58 (1) ◽  
pp. 20-24 ◽  
Author(s):  
M. P. Madan
Keyword(s):  
Thermodynamic Parameters ◽  
Molecular Motion ◽  
Polar Solvent ◽  
Relaxation Times ◽  
Relaxation Processes ◽  
Polar Components ◽  
Dielectric Absorption ◽  
System A ◽  
Dielectric Data ◽  
Activated State

The dielectric absorption of quinoline, isoquinoline, and their binary mixtures has been studied in the microwave region over a range of temperatures in dilute benzene and n-heptane solutions. The relaxation times and the thermodynamic parameters for the activated state have been determined using the measured dielectric data. The results obtained have been discussed in terms of the molecular motion of the system. A relation has been proposed to represent the relaxation behavior of a system of two Debye-type polar components in a non-polar solvent. The relation has been tested by comparing the calculated values with those determined experimentally for a few systems consisting of similar, simple rigid polar molecules.

Temperature Dependence of Dynamic Properties of Elastomers. Relaxation Distributions

1952 ◽  
Vol 25 (4) ◽  
pp. 720-729 ◽  
Author(s):  
John D. Ferry ◽  
Edwin R. Fitzgerald ◽  
Lester D. Grandine ◽  
Malcolm L. Williams
Keyword(s):  
Distribution Function ◽  
Temperature Dependence ◽  
Dynamic Properties ◽  
Relaxation Times ◽  
Dynamic Mechanical Properties ◽  
Relaxation Processes ◽  
The Real ◽  
Reduced Frequency ◽  
Dynamic Rigidity ◽  
Composite Curve

Abstract By the use of reduced variables, the temperature dependence and frequency dependence of dynamic mechanical properties of rubberlike materials can be interrelated without any arbitrary assumptions about the functional form of either The definitions of the reduced variables are based on some simple assumptions regarding the nature of relaxation processes. The real part of the reduced dynamic rigidity, plotted against the reduced frequency, gives a single composite curve for data over wide ranges of frequency and temperature; this is true also for the imaginary part of the rigidity or the dynamic viscosity. The real and imaginary parts of the rigidity, although independent measurements, are interrelated through the distribution function of relaxation times, and this relation provides a check on experimental results. First and second approximation methods of calculating the distribution function from dynamic data are given. The use of the distribution function to predict various types of time-dependent mechanical behavior is illustrated.

Relaxation Time Spectrum, Elasticity, and Viscosity of Rubber. I

1954 ◽  
Vol 27 (1) ◽  
pp. 36-54 ◽  
Author(s):  
W. Kuhn ◽  
O. Künzle ◽  
A. Preissmann
Keyword(s):  
Relaxation Time ◽  
Relaxation Times ◽  
Time Spectrum ◽  
Test Sample ◽  
Elastic Behavior ◽  
Relaxation Processes ◽  
Relaxation Time Spectrum ◽  
Restoring Force ◽  
Constant Length ◽  
Rapid Deformation

Abstract By rapid deformation of a medium in which linear molecules are present, various changes are produced simultaneously in the latter. These changes are more or less independent of one another, and can release independently and totally or partially by rearrangement of valence distances and valence angles in the chain molecules. By virtue of such relaxation processes, a portion of the stress originating in the rapid deformation disappears, with a changing time requirement for the various portions. A relaxation time spectrum is thus formed. The relaxation time spectrum consists of a finite number of restoring force mechanisms with proper relaxation times or of a continuous spectrum. Both the creep curves (the dependence of the length of a body on time at constant load), and stress relaxation (decay of the stress observed in test sample kept at constant length after rapid deformation), as well as the total visco-elastic behavior, especially the behavior at constant periodic deformation of the test sample, are determined by the relaxation time spectrum. The appropriate Quantitative relationships were derived.

scholarly journals A Bis-Monophospholyl Dysprosium Cation Showing Magnetic Hysteresis at 48 Kelvin

2019 ◽  
Author(s):  
Peter Evans ◽  
Daniel Reta ◽  
George F. S. Whitehead ◽  
Nicholas Chilton ◽  
David Mills
Keyword(s):  
Data Storage ◽  
Single Molecule ◽  
Structural Changes ◽  
Elevated Temperatures ◽  
Spin Dynamics ◽  
Magnetic Hysteresis ◽  
Relaxation Times ◽  
Magnetic Memory ◽  
Relaxation Processes ◽  
Potential Applications

Single-molecule magnets (SMMs) have potential applications in high-density data storage, but magnetic relaxation times at elevated temperatures must be increased to make them practically useful. <i>Bis</i>-cyclopentadienyl lanthanide sandwich complexes have emerged as the leading candidates for SMMs that show magnetic memory at liquid nitrogen temperatures, but the relaxation mechanisms mediated by aromatic C<sub>5</sub> rings have not been fully established. Here we synthesise a <i>bis</i>-monophospholyl dysprosium SMM [Dy(Dtp)<sub>2</sub>][Al{OC(CF<sub>3</sub>)<sub>3</sub>}<sub>4</sub>] (<b>1</b>, Dtp = {P(C<sup>t</sup>BuCMe)<sub>2</sub>}) by the treatment of <i>in situ</i>-prepared “[Dy(Dtp)<sub>2</sub>(C<sub>3</sub>H<sub>5</sub>)]” with [HNEt<sub>3</sub>][Al{OC(CF<sub>3</sub>)<sub>3</sub>}<sub>4</sub>]. SQUID magnetometry reveals that <b>1</b> has an effective barrier to magnetisation reversal of 1,760 K (1,223 cm<sup>–1</sup>) and magnetic hysteresis up to 48 K. <i>Ab initio</i> calculation of the spin dynamics reveal that transitions out of the ground state are slower in <b>1</b> than in the first reported dysprosocenium SMM, [Dy(Cp<sup>ttt</sup>)<sub>2</sub>][B(C<sub>6</sub>F<sub>5</sub>)<sub>4</sub>] (Cp<sup>ttt</sup> = C<sub>5</sub>H<sub>2</sub><sup>t</sup>Bu<sub>3</sub>-1,2,4), however relaxation is faster in <b>1</b> overall due to the compression of electronic energies and to vibrational modes being brought on-resonance by the chemical and structural changes introduced by the <i>bis</i>-Dtp framework. With the preparation and analysis of <b>1</b> we are thus able to further refine our understanding of relaxation processes operating in <i>bis</i>-C<sub>5</sub>/C<sub>4</sub>P sandwich lanthanide SMMs, which is the necessary first step towards rationally achieving higher magnetic blocking temperatures in these systems in future.

scholarly journals The Dynamic Properties of 5Cb Filled with Aerosil Particles Investigated by Pcs

1999 ◽  
Vol 559 ◽  
Author(s):  
F.M. Aliev ◽  
M. Kreuzer ◽  
Yu.P. Panarin
Keyword(s):  
Liquid Crystal ◽  
Temperature Dependence ◽  
Relaxation Process ◽  
Nematic Liquid Crystal ◽  
Broad Spectrum ◽  
Dynamic Properties ◽  
Relaxation Times ◽  
Correlation Spectroscopy ◽  
Relaxation Processes ◽  
Optoelectronic Application

ABSTRACTNematic liquid crystal filled with Aerosil particles, a prospective composite material for optoelectronic application, has been investigated by static light scattering and Photon Correlation Spectroscopy (PCS). The Aerosil particles in filled nematic liquid crystals (FN) form a network structure with LC domains about 2500 Å in size with a random distribution of the director orientation of each domain.We found that the properties of 5CB are considerably affected by the network. The N-I phase transition in filled 5CB was found to be smeared out and depressed. PCS experiments show that two new relaxation processes appear in filled 5CB in addition to the director fluctuation process in bulk. The slow relaxation process, with a broad spectrum of relaxation times, is somewhat similar to the slow decay, which is observed in confined nematic liquid crystal.The middle frequency process was assigned to the director fluctuations in the surface layer formed at the particle-LC interface. The decay function describing this relaxation process is a stretched exponential (β ≍ 0.7). The temperature dependence of the relaxation times of the middle frequency obeys the Vogel-Rilcher law. Such a temperature dependence, accompanied by a broad spectrum of relaxation times suggests that the dynamics of the director fluctuations near the Aerosil particle-LC interface is glass-like.

Structural Relaxation Process in CuHfTi Amorphous Alloys

2009 ◽  
Vol 283-286 ◽  
pp. 533-538 ◽  
Author(s):  
Kazumasa Yamada ◽  
N. Shinagawa ◽  
M. Sogame ◽  
I.A. Figueroa ◽  
Hywel A. Davies ◽  
...  
Keyword(s):  
Activation Energy ◽  
Relaxation Process ◽  
Structural Relaxation ◽  
Amorphous Alloys ◽  
Melt Spinning ◽  
Amorphous Materials ◽  
Ternary Alloys ◽  
Relaxation Processes ◽  
Scanning Calorimetry ◽  
Structure Relaxation

The aim of this research is to clarify a quantitative evaluation in the structural relaxation processes focusing on the activation energy in Cu based amorphous alloys. The activation energy for structural relaxation process in a metal type amorphous CuHfTi ternary alloys, with cross sections of typically 0.03 mm x 2.0 mm, prepared by chill-block melt spinning has been investigated by Differential Scanning Calorimetry (DSC) with a cyclically heating technique. Activation energies for structural relaxation with a spatial quantity in amorphous materials have been discussed by use of a relaxed ratio function that depends on annealing temperature and time. In the present work, the distributions for the Activation Energy Spectrum (AES) were observed almost 152 kJmol-1 (1.58 eV). Another result has been also established that the “reversible” AES model energy distribution though the cyclically structure relaxation occurs even in amorphous Cu60Hf20Ti20 alloy.

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