THE POLARIZATION OF LIQUIDS AND THEIR SATURATED VAPORS IN THE CRITICAL TEMPERATURE REGION

1936 ◽  
Vol 14b (3) ◽  
pp. 90-95
Author(s):  
J. Marsden ◽  
O. Maass
Keyword(s):  
Critical Temperature ◽  
Methyl Ether ◽  
Temperature Region ◽  
Room Temperature ◽  
Saturated Vapor ◽  
Dielectric Constants

The values of the so-called polarization of methyl ether (liquid and saturated vapor) and propylene (liquid and saturated vapor), from room temperature to the critical temperature, are given. In both liquids this polarization is independent of the temperature to within a few degrees of the critical temperature. Calculations show that the polarizations of a liquid and its saturated vapor may be equal above the critical temperature, even though the dielectric constants of the liquid and its saturated vapor, as well as their densities, are different.

THE DISCONTINUITY IN THE DIELECTRIC CONSTANT OF LIQUIDS AND THEIR SATURATED VAPORS AT THE CRITICAL TEMPERATURE

1935 ◽  
Vol 13b (5) ◽  
pp. 296-307 ◽  
Author(s):  
J. Marsden ◽  
O. Maass
Keyword(s):  
Dielectric Constant ◽  
Critical Temperature ◽  
Methyl Ether ◽  
Temperature Region ◽  
Room Temperature ◽  
Saturated Vapor ◽  
Dielectric Constants ◽  
Large Temperature ◽  
Critical Temperatures ◽  
Dielectric Cell

A dielectric cell, which is specially adapted to a study of the dielectric constants of liquid and gas over a large temperature range, including the critical temperature region, is described. The dielectric constants of methyl ether (liquid and saturated vapor) and propylene (liquid and saturated vapor), from room temperature to eight degrees above the critical temperatures, are given. The measurements show that the dielectric constants of liquid and gas are not identical at the critical temperature. These results are in agreement with previous work carried out in this laboratory on the discontinuity in properties of the medium above and below the point of disappearance of the meniscus.

LOW LOSS DIELECTRIC MATERIALS FOR HIGH FREQUENCY APPLICATIONS

2009 ◽  
Vol 23 (17) ◽  
pp. 3649-3654 ◽  
Author(s):  
MOHAN V. JACOB
Keyword(s):  
High Frequency ◽  
Room Temperature ◽  
Low Cost ◽  
Dielectric Materials ◽  
Dielectric Constants ◽  
Transmission Losses ◽  
Low Loss ◽  
Microwave Characterization ◽  
Materials Used ◽  
Low Temperature Electronics

The microwave properties of some of the low cost materials which can be used in high frequency applications with low transmission losses are investigated in this paper. One of the most accurate microwave characterization techniques, Split Post Dielectric Resonator technique (SPDR) is used for the experimental investigation. The dielectric constants of the 3 materials scrutinized at room temperature and at 10K are 3.65, 2.42, 3.61 and 3.58, 2.48, 3.59 respectively. The corresponding loss tangent values are 0.00370, 0.0015, 0.0042 and 0.0025, 0.0009, 0.0025. The high frequency transmission losses are comparable with many of the conventional materials used in low temperature electronics and hence these materials could be implemented in such applications.

Conductivity and Permittivity Studies in the Diluted Perovskite System [(NH3)(CH2)6(NH3)]FexZn1-xCl4, x=1, 0.8, 0.5, and 0

2002 ◽  
Vol 57 (11) ◽  
pp. 897-908 ◽  
Author(s):  
M. F. Mostafa ◽  
M. M. AbdelKader ◽  
S. S. Arafat
Keyword(s):  
Temperature Region ◽  
Room Temperature ◽  
Conduction Mechanism ◽  
High Temperature Region ◽  
Frequency Dependent ◽  
Arrhenius Relation ◽  
Zn Addition ◽  
Series Type ◽  
Type Conduction ◽  
Band Type

The dielectric permittivity and AC conductivity of the perovskite-like system [(NH3)(CH2)6(NH3)]FexZn1-xCl4 (HDAFxZ1-x), where x=1, 0.8, 0.5 and 0, were measured at different frequencies in the temperature range 100 K<T<430 K. At temperatures below 273 K, for x=1 the material exhibits a transition at (245±1) K, while for x=0 transitions at (155±5) K, (220±4) K and (255±2) K were found. A rotational-type transition in the range 295 - 305 K was found for the Fe-containing materials. Ferroelectric transitions were observed in the high temperature region for all four concentrations. Differential thermal scanning confirmed the existence of the phase transitions above room temperature. The conductivity decreases with Zn addition, an the conduction mechanism varies with the temperature and concentration. Extrinsic conduction prevails for T<150 K for all concentrations. At intermediate temperatures an Arrhenius relation with frequency dependent activation energy (ΔE=0.46 - 0.06 eV) is observed for Fecontaining materials. The frequency dependent conductivity for all materials has a linear response following the power law: σac=A(T) ·ωS(T) with the exponent s varying with temperature and composition. At high temperatures, for Zn-rich materials series type conduction with s ∼ 0.6±0.1 is identified, while for Fe-rich materials band type conduction prevails. In the low temperature region ionic hopping prevails.

New Perovskite Nanomaterials and Their Integrations into High-k Dielectrics

2011 ◽  
Vol 2011 (CICMT) ◽  
pp. 000072-000077
Author(s):  
Minoru Osada ◽  
Takayoshi Sasaki
Keyword(s):  
Dielectric Properties ◽  
Room Temperature ◽  
Bottom Electrode ◽  
Dielectric Constants ◽  
Dielectric Films ◽  
Layered Perovskite ◽  
Layer By Layer ◽  
High K ◽  
High K Dielectric ◽  
High Dielectric

We report on a bottom-up manufacturing for high-k dielectric films using a novel nanomaterial, namely, a perovskite nanosheet (LaNb2O7) derived from a layered perovskite by exfoliation. Solution-based layer-by-layer assembly of perovskite nanosheets is effective for room-temperature fabrication of high-k nanocapacitors, which are directly assembled on a SrRuO3 bottom electrode with an atomically sharp interface. These nanocapacitors exhibit high dielectric constants (k &gt; 50) for thickness down to 5 nm while eliminating problems resulting from the size effect. We also investigate dielectric properties of perovskite nanosheets with different compositions (LaNb2O7, La0.95Eu0.05Nb2O7, and Eu0.56Ta2O7) in order to study the influence of A- and B-site modifications on dielectric properties.

A STUDY OF THE COEXISTENCE OF THE LIQUID AND GASEOUS STATES OF AGGREGATION IN THE CRITICAL TEMPERATURE REGION. ETHYLENE

1940 ◽  
Vol 18b (4) ◽  
pp. 118-121 ◽  
Author(s):  
S. N. Naldrett ◽  
O. Maass
Keyword(s):  
Critical Temperature ◽  
Temperature Region ◽  
Previous Investigation ◽  
Coexistence Curve

The coexistence curve of ethylene has been determined in a manner similar to that described in a previous investigation on ethane (9). It is found to lie entirely within the coexistence curve determined by P-V-T methods by other investigators (6). This is considered to be evidence for the formation of a dispersion of liquid and vapour before the critical temperature is reached. The term "critical dispersion temperature" is suggested for the temperature at the apex of the coexistence curve determined by the disappearance of the meniscus in a bomb shaken in the manner described in this investigation. The apex of the curve determined by P-V-T methods is the true critical temperature, beyond which liquid is not stable. The classical critical temperature, determined by the disappearance of the meniscus in a stationary bomb, is an indefinite point between these two.

How Reliable is the Cuprates System to Recent Technology?

2016 ◽  
Vol 6 (4) ◽  
pp. 1534
Author(s):  
Emetere M.E. ◽  
Awojoyogbe O.B. ◽  
Uno U.E. ◽  
Isah K.U. ◽  
Sanni E.S. ◽  
...  
Keyword(s):  
Critical Temperature ◽  
Room Temperature ◽  
Engineering Application ◽  
Experimental Results ◽  
Future Research ◽  
Mathematical Approach ◽  
Experimental Room ◽  
High Tc ◽  
High Tc Superconductor

The emergence of cuprates as a high Tc superconductor gave high hopes in the discovery of a room temperature superconductor. It is almost three decades and the highest critical temperature attained on the cuprates is about 135K. A brief overview was conducted on the progress made so far on the cuprates. A mathematical approach was used to design a formula which could determine the experimental results of critical temperature of versed cuprates superconductors. The result of our findings shows that the possibility of attaining the experimental room temperature cuprates superconductor seems very narrow. The study recommended an elaborate approach on the hybridization of cuprates for future research. Hence, there is possibility of having cuprates with wide engineering application.

SOLUBILITY MEASUREMENTS IN THE REGION OF THE CRITICAL TEMPERATURE

1940 ◽  
Vol 18b (9) ◽  
pp. 293-304 ◽  
Author(s):  
C. H. Holder ◽  
O. Maass
Keyword(s):  
Critical Temperature ◽  
Temperature Region ◽  
Pressure Change ◽  
Liquid Phases

An apparatus for the measurement of solubility in the critical temperature region has been constructed. This apparatus permits samples to be taken from the upper and lower regions (vapour and liquid phases, if below critical temperature) of a system without volume or pressure change so that equilibrium is not disturbed.Solubility measurements of hexachloroethane in ethane have been made through the critical temperature region.

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