Chemical Bonding of Fluorine Atoms in Siof Alloys: Microscopic Mechanisms for Reductions in the Dielectric Constant Relative to SiO2

1996 ◽  
Vol 443 ◽  
Author(s):  
G. Lucovsky ◽  
H. Yang
Keyword(s):  
Molecular Structure ◽  
Dielectric Constant ◽  
Ab Initio Calculations ◽  
Infrared Absorption ◽  
Chemical Bonding ◽  
Dielectric Constants ◽  
Low Concentrations ◽  
Inductive Effects ◽  
Infrared Absorption Spectra ◽  
Static Dielectric Constants

AbstractSi-O-F alloys have static dielectric constants (εs) significantly lower than SiO2. Infrared absorption spectra provide the basis modeling the molecular structure of these alloys. Contributions of electronic and vibrational transitions to εs are discussed in terms of an empirical chemical bonding model. Ab initio calculations are then used to identify inductive effects of Si- F bonds on the properties of Si-O-Si groups that are back-bonded to the Si atom of the Si-F group. These calculations provide a theoretical framework for understanding how relatively low concentrations of F atoms produce the significant decreases in εs reported for Si-O-F alloys.

The effects of pressure on the density, dielectric constant, and viscosity of several hydrocarbons and other organic liquids

1969 ◽  
Vol 47 (6) ◽  
pp. 893-899 ◽  
Author(s):  
D. W. Brazier ◽  
G. R. Freeman
Keyword(s):  
Molecular Structure ◽  
Dielectric Constant ◽  
Carbon Tetrachloride ◽  
Pressure Range ◽  
High Pressures ◽  
Liquid Structure ◽  
Dielectric Constants ◽  
Pressure Effects ◽  
Organic Liquids ◽  
Increasing Temperature

The effects of pressures up to 4 kbar on the density, dielectric constant, and viscosity of n-pentane, n-hexane, n-octane, cyclopentane, methylcyclohexane, and 2,2-dimethylbutane (DMB) were measured at 30 °C. The pressure effects on the viscosities of n-hexane and n-octane were also determined at 0 and 60°. The densities of diethyl ether and cyclopentanone and the dielectric constant of carbon tetrachloride at high pressures are also recorded. The densities of the hydrocarbons increased by 20–30% and the dielectric constants increased by 11–16% as the pressure was increased from 1 to 4000 bars at 30°, but the viscosities increased by 695–2352% over the same pressure range. Carbon tetrachloride froze at 1500 bars at 30°, and cyclopentanone froze at 3500 bars at about 20°. In agreement with earlier work on other liquids, the value of the Clausius–Mosotti function (ε − 1)V/(ε + 2) for the present compounds decreased slightly with increasing pressure. The viscosity at a given pressure decreased slightly with increasing temperature, and temperature effect increased with increasing pressure. In general, the smaller the compressibility of the liquid, the greater was the effect of pressure on the viscosity; DMB was an exception because its viscosity increased abnormally rapidly with pressure. Molecular structure and liquid structure have greater influences on the pressure dependence of viscosity than on that of density or dielectric constant.

Dielectric constant enhancement of non-fullerene acceptors via side-chain modification

2015 ◽  
Vol 51 (74) ◽  
pp. 14115-14118 ◽  
Author(s):  
Jenny E. Donaghey ◽  
Ardalan Armin ◽  
Paul L. Burn ◽  
Paul Meredith
Keyword(s):  
Dielectric Constant ◽  
Electron Acceptors ◽  
Dielectric Constants ◽  
Side Chain ◽  
Static Dielectric Constants

Substitution of alkyl solubilizing groups with short glycol chains can give non-fullerene electron acceptors with static dielectric constants of up to 9.8.

Microscopic Mechanisms for Reduced Static Dielectric Constants in Si-O-F Alloy Films

1997 ◽  
Vol 476 ◽  
Author(s):  
H. Yang ◽  
G. Lucovsky
Keyword(s):  
Dielectric Constant ◽  
Alloy System ◽  
Dielectric Constants ◽  
Force Constants ◽  
Significant Fraction ◽  
Alloy Films ◽  
Bond Stretching ◽  
Effective Charges ◽  
Static Dielectric Constants ◽  
Recent Attention

AbstractThere is considerable interest in insulators with static dielectric constants lower than SiO2; an alloy system attracting recent attention is Si-O-F. Alloying of F atoms into plasma-deposited SiO2 films leads to major changes in the SiO2 bond-stretching and -bending infrared bands accounting for a significant fraction of the reduction in the dielectric constant. These changes are explained by F induced modifications of force constants and effective charges of the neighboring Si-O-Si groups.

First-Principles Calculations of the Dielectric Constant for the GeO2 Films

2011 ◽  
Vol 470 ◽  
pp. 60-65 ◽  
Author(s):  
Masahiro Tamura ◽  
Jun Nakamura ◽  
Akiko Natori
Keyword(s):  
Dielectric Constant ◽  
Electric Fields ◽  
Ground State ◽  
First Principles ◽  
Rutile Phase ◽  
Dielectric Constants ◽  
Ionic Character ◽  
First Principles Calculations ◽  
External Electric Fields ◽  
Static Dielectric Constants

Dielectric properties of α-quartz and rutile-GeO2 thin-films are investigated using first-principles ground-state calculations in external electric fields. The optical and the static dielectric constants inside the films have nearly-constant values, corresponding to their bulk values, while only at the topmost surface layer the dielectric constants decrease distinctly. It has been found that the dielectric constant for the rutile-GeO2 is larger than that for the α-quartz one, which stems from the larger ionic character of the Ge-O bond for the rutile phase.

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