Ultrasonic Absorption in Fused Silica at Low Temperatures and High Frequencies

1955 ◽  
Vol 38 (4) ◽  
pp. 125-131 ◽  
Author(s):  
O. L. ANDERSON ◽  
H. E. BOMMEL
Keyword(s):  
Low Temperatures ◽  
Fused Silica ◽  
Ultrasonic Absorption ◽  
High Frequencies

The anomalous skin effect

1952 ◽  
Vol 215 (1123) ◽  
pp. 481-497 ◽  
Keyword(s):  
Free Path ◽  
Low Temperatures ◽  
Skin Effect ◽  
Mean Free Path ◽  
Skin Depth ◽  
Surface Conductance ◽  
High Frequencies ◽  
Surface Imperfections ◽  
Anomalous Skin Effect ◽  
Cadmium Lead

The anomalous skin effect arises in good conductors at low temperatures and high frequencies when the electronic mean free path becomes comparable with or greater than the classically calculated skin depth. Measurements have been made on a number of metals at frequencies of 1200 and 3600 Mc/s, and the form of variation of r. f. surface conductance with d. c. conductivity agrees well with that predicted theoretically by Reuter & Sondheimer, assuming that the electrons are scattered diffusely when they hit the surface of the metal. From the results, estimates are made of the effective value of σ/ l , the ratio of d. c. conductivity to mean free path, and hence of the free surface area of the occupied region of k -space. The estimate for copper agrees well with that expected theoretically; those for silver and gold are rather lower than the theoretical values. For the other metals investigated, tin, cadmium, lead and aluminium, no theoretical estimates are available. The results are very sensitive to the presence of surface imperfections; the effect of these is discussed.

Saturation of the ultrasonic absorption in vitreous silica at low temperatures

1972 ◽  
Vol 42 (3) ◽  
pp. 253-255 ◽  
Author(s):  
S. Hunklinger ◽  
W. Arnold ◽  
St. Stein ◽  
R. Nava ◽  
K. Dransfeld
Keyword(s):  
Low Temperatures ◽  
Vitreous Silica ◽  
Ultrasonic Absorption

scholarly journals Review of the Effects of the Influence of External Vibrations on the Freezing Point of Water

2020 ◽  
Vol 320 ◽  
pp. 00032
Author(s):  
Emmanuele Adorni ◽  
Mikhail Ivanov ◽  
Roberto Revetria
Keyword(s):  
Liquid State ◽  
High Frequency ◽  
Low Temperatures ◽  
Freezing Point ◽  
Tap Water ◽  
Distilled Water ◽  
High Frequencies ◽  
High Frequency Vibrations

With this paper we want to provide a first glance at some of those researches that studied how to lower the freezing point of water below the ordinarily point by using external vibrations. All the researches started with experiments on distilled water (obtained with different methodology depending on the experiment) and then moving forward to experiments on tap water (contaminated with a known amount of substances). In all cases, methods to bring the samples to an undercooled state were applied at first. Through high frequency vibrations it has been studied how the formation of ice in a vessel of water can be controlled mainly thanks to the development of the phenomenon of cavitation in the water. By increasing the pressure in certain zones of the samples it was possible to study the phenomena linked to water freezing. Some experiments showed how, even with high frequencies, it is still difficult to obtain reliable results on the topic of keeping the water in a liquid state in conditions of low temperatures and with vibrations applied to the fluid.

Dielectric Properties of Pd/Y8Z Composites

1999 ◽  
Vol 575 ◽  
Author(s):  
Mark G.H.M. Hendriks ◽  
Henk Verwei ◽  
Manon P. Timmerman
Keyword(s):  
Dielectric Properties ◽  
Percolation Threshold ◽  
Double Layer ◽  
Low Temperatures ◽  
Room Temperature ◽  
Electronic Conductivity ◽  
Impedance Measurements ◽  
High Frequencies ◽  
A Value ◽  
Double Layer Capacity

ABSTRACTImpedance measurements are performed on Pd/Y8Z composites. At 500 'C a 2- 108 times enhancement of the permittivity of the composite at a Pd composition near the percolation threshold for electronic conductivity relative to Y8Z at room temperature is obtained. At high frequencies, the enhancement decreases to a value comparable to geometric capacity of the composite as the double-layer capacity diminishes. At relatively low temperatures the capacity of Y8Z, due to ionic polarisability, increases with temperature.

scholarly journals An Experimental Study of the Formation of Talc through CaMg(CO3)2–SiO2–H2O Interaction at 100–200°C and Vapor-Saturation Pressures

Geofluids ◽  
2017 ◽  
Vol 2017 ◽  
pp. 1-14 ◽  
Author(s):  
Ye Wan ◽  
Xiaolin Wang ◽  
I-Ming Chou ◽  
Wenxuan Hu ◽  
Yang Zhang ◽  
...  
Keyword(s):  
Low Temperatures ◽  
Fused Silica ◽  
X Ray Diffraction ◽  
In Situ Raman Spectroscopy ◽  
X Ray ◽  
In Situ Raman ◽  
Geological Processes ◽  
Partial Pressures ◽  
Increasing Temperature

The metamorphic interaction between carbonate and silica-rich fluid is common in geological environments. The formation of talc from dolomite and silica-rich fluid occurs at low temperatures in the metamorphism of the CaO–MgO–SiO2–CO2–H2O system and plays important roles in the formation of economically viable talc deposits, the modification of dolomite reservoirs, and other geological processes. However, disagreement remains over the conditions of talc formation at low temperatures. In this study, in situ Raman spectroscopy, quenched scanning electron microscopy, micro-X-ray diffraction, and thermodynamic calculations were used to explore the interplay between dolomite and silica-rich fluids at relatively low temperatures in fused silica tubes. Results showed that talc formed at ≤200°C and low CO2partial pressures (PCO2). The reaction rate increased with increasing temperature and decreased with increasingPCO2. The major contributions of this study are as follows:(1)we confirmed the formation mechanism of Mg-carbonate-hosted talc deposits and proved that talc can form at ≤200°C;(2)the presence of talc in carbonate reservoirs can indicate the activity of silica-rich hydrothermal fluids; and (3) the reactivity and solubility of silica require further consideration, when a fused silica tube is used as the reactor in highP–Texperiments.

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