Thermally activated relaxation processes in vitreous silica: An investigation by Brillouin scattering at high pressures

1992 ◽  
Vol 45 (6) ◽  
pp. 2750-2760 ◽  
Author(s):  
D. Tielbürger ◽  
R. Merz ◽  
R. Ehrenfels ◽  
S. Hunklinger
Keyword(s):  
High Pressures ◽  
Brillouin Scattering ◽  
Vitreous Silica ◽  
Relaxation Processes ◽  
Thermally Activated

Relaxation Phenomena and Thermodynamics of Liquids at Very High Pressures

1996 ◽  
Vol 464 ◽  
Author(s):  
W. F. Oliver
Keyword(s):  
High Pressure ◽  
Glass Transition ◽  
Light Scattering ◽  
Liquid State ◽  
High Pressures ◽  
Equations Of State ◽  
Brillouin Scattering ◽  
Dynamic Properties ◽  
Relaxation Processes ◽  
Glass Forming

ABSTRACTComplex liquid glass-forming systems ranging from those composed of simple molecules to polymer melts and amorphous polymers have been studied extensively as a function of temperature resulting in a basic understanding of liquid-state dynamics and glass transition phenomenology as these systems are supercooled to the vitreous state. An important aspect of this problem that remains largely unexplored, and that is relevant to the topic of this symposium, involves liquid-state dynamics and vitrification (as well as crystallization) in the regime of high pressure and high density. We describe work on “fragile” to “intermediate strength” simple organic glass-forming liquids where both temperature (T) and pressure (P) are varied. Diamond anvil cells are used to achieve pressures exceeding 10 GPa. Several optical and light scattering techniques are used to explore both static and dynamic properties of these systems. High-pressure Brillouin scattering enables us to model the longitudinal relaxation time in these systems as well as their equations of state. These can now be refined by direct measurements of the pressure dependence of the glass transition, Tg(P). Finally, we summarize depolarized light scattering studies which allow us to compare both the isobaric and isothermal evolution of structural (α) and fast (β) relaxation processes.

scholarly journals Tetragonal–Cubic Phase Transition and Low-Field Dielectric Properties of CH3NH3PbI3 Crystals

Materials ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4215
Author(s):  
Roxana E. Patru ◽  
Hamidreza Khassaf ◽  
Iuliana Pasuk ◽  
Mihaela Botea ◽  
Lucian Trupina ◽  
...  
Keyword(s):  
Dielectric Properties ◽  
Current Knowledge ◽  
Cubic Phase ◽  
Relaxation Processes ◽  
Temperature Dependent ◽  
Thermally Activated ◽  
Low Field ◽  
Conduction Mechanisms ◽  
Temperature Ranges ◽  
Nyquist Plots

The frequency and temperature dependence of dielectric properties of CH3NH3PbI3 (MAPI) crystals have been studied and analyzed in connection with temperature-dependent structural studies. The obtained results bring arguments for the existence of ferroelectricity and aim to complete the current knowledge on the thermally activated conduction mechanisms, in dark equilibrium and in the presence of a small external a.c. electric field. The study correlates the frequency-dispersive dielectric spectra with the conduction mechanisms and their relaxation processes, as well as with the different transport regimes indicated by the Nyquist plots. The different energy barriers revealed by the impedance spectroscopy highlight the dominant transport mechanisms in different frequency and temperature ranges, being associated with the bulk of the grains, their boundaries, and/or the electrodes’ interfaces.

Brillouin scattering study of liquid methane under high pressures and high temperatures

2010 ◽  
Vol 133 (4) ◽  
pp. 044503 ◽  
Author(s):  
Min Li ◽  
Fangfei Li ◽  
Wei Gao ◽  
Chunli Ma ◽  
Liyin Huang ◽  
...  
Keyword(s):  
High Temperatures ◽  
High Pressures ◽  
Brillouin Scattering ◽  
Scattering Study ◽  
Liquid Methane

Magnetic field and dilution effects on the slow relaxation of {Er3} triangle-based arsenotungstate single-molecule magnets

2020 ◽  
Vol 49 (35) ◽  
pp. 12458-12465 ◽  
Author(s):  
Hanhan Chen ◽  
Lin Sun ◽  
Jinpeng Zhang ◽  
Zikang Xiao ◽  
Pengtao Ma ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Single Molecule ◽  
Magnetic Relaxation ◽  
Slow Relaxation ◽  
Relaxation Processes ◽  
Single Molecule Magnets ◽  
Thermally Activated ◽  
Slow Magnetic Relaxation ◽  
Dilution Effects

Triangular {Er3} cluster containing POM exhibits field-induced two thermally activated relaxation processes. Whereas, the diamagnetic dilution sample indicates slow magnetic relaxation with the QTM being partially suppressed.

Anelastic Behavior due to Interstitial Oxygen in SmBa2Cu3O7-δ

2006 ◽  
Vol 530-531 ◽  
pp. 557-561
Author(s):  
Rubens Maribondo Nascimento ◽  
Juliana Maria de Albuquerque Gimenez ◽  
Carlos Roberto Grandini ◽  
Alfredo Gonçalves da Cunha
Keyword(s):  
Internal Friction ◽  
Oscillation Frequency ◽  
Orthorhombic Phase ◽  
Precise Determination ◽  
Relaxation Processes ◽  
Interstitial Oxygen ◽  
X Ray Diffraction ◽  
Critical Temperatures ◽  
Thermally Activated ◽  
Relaxation Structure

The composite SmBa2Cu3O7-δ (Sm-123), obtained by the substitution of the ion Y for Sm in the very well known and studied YBa2Cu3O7-δ (Y-123), is potentially attractive for better understanding superconductivity mechanisms and for its applications as electronic devices. Sm-123 samples show higher critical temperatures than Y-123 ones do and a larger solubility of Sm in Ba-Cu-O solvent, which makes their growth process faster. When oxygen is present interstitially, it strongly affects the physical properties of the material. The dynamics of oxygen can be investigated by anelastic spectroscopy measurements, a powerful technique for the precise determination of the oscillation frequency and the internal friction when atomic jumps are possible. Anelastic spectroscopy allows determining the elasticity modulus (related to the oscillation frequency) and the elastic energy loss (related to the internal friction) as a function of the temperature. The sample was also investigated by X-ray diffraction (XRD), scanning electronic microscopy (SEM), and electric resistivity. The results obtained show a thermally activated relaxation structure composed by at least 3 relaxation processes. These processes may be attributed to the jumps of oxygen atoms present of the Cu-O plane in the orthorhombic phase.

Sound velocity of neon at high pressures and temperatures by Brillouin scattering

2019 ◽  
Vol 104 (11) ◽  
pp. 1650-1655
Author(s):  
Wei Wei ◽  
Xinyang Li ◽  
Ningyu Sun ◽  
Sergey N. Tkachev ◽  
Zhu Mao
Keyword(s):  
Phase Transition ◽  
High Pressures ◽  
Velocity Structure ◽  
Solid Phase ◽  
Brillouin Scattering ◽  
Compressional Wave ◽  
Rare Gases ◽  
Apparent Reduction ◽  
Diamond Anvil ◽  
Increasing Temperature

Abstract In this study, we have determined the combined effect of pressure and temperature on the compressional-wave velocity (VP) of Ne up to 53 GPa and 1100 K using Brillouin scattering in externally heated diamond-anvil cells. The phase transition from the supercritical fluid to solid phase was observed to cause a 10.5–11% jump in VP, and the magnitude in the VP contrast across the phase transition increases with temperature. In addition, we have observed an abnormal reduced increase rate of VP with pressure in the supercritical Ne fluid at both 800 and 1100 K before the transition to the solid phase. VP of the solid Ne exhibits a nonlinear increase with pressure at all the investigated temperatures. The elevating temperature was noted to cause an apparent reduction in VP, yet the reduction in VP caused by increasing temperature dramatically decreases at higher pressures. At 20 GPa, increasing temperature by 100 K can lower the VP of Ne by 2.4%. Yet elevating temperature by 100 K can only reduce the VP by 0.4% at 50 GPa. We further compare VP of Ne to that of other rare gases, including Ar, Kr, and Xe. At 300 K, VP of Ne shows a stronger dependence on pressure than both Kr and Xe. Moreover, increasing temperature can produce a greater reduction in VP of Ne than that of Ar below 50 GPa. Our measured VP of Ne is also useful for understanding the velocity structure of giant planets, such as Jupiter.

Densification of vitreous silica under static high pressures higher than 2 Mb

1971 ◽  
Vol 34 (2) ◽  
pp. 107-108 ◽  
Author(s):  
N. Kawai ◽  
S. Mochizuki ◽  
H. Fujita
Keyword(s):  
High Pressures ◽  
Vitreous Silica
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