Dielectric relaxation in water‐tert‐butanol mixtures. The water rich region

1993 ◽  
Vol 99 (10) ◽  
pp. 8115-8119 ◽  
Author(s):  
D. Fioretto ◽  
A. Marini ◽  
M. Massarotti ◽  
G. Onori ◽  
L. Palmieri ◽  
...  
Keyword(s):  
Dielectric Relaxation ◽  
Rich Region ◽  
Tert Butanol

Solvent effects on the reactivity of solvated electrons with ions in tert-butanol/water mixtures

1995 ◽  
Vol 73 (3) ◽  
pp. 392-400 ◽  
Author(s):  
Yixing Zhao ◽  
Gordon R. Freeman
Keyword(s):  
Solvent Effects ◽  
Pure Water ◽  
Solvated Electrons ◽  
Rich Region ◽  
Tert Butanol ◽  
Einstein Model ◽  
Activation Energy For Diffusion ◽  
Minimum Number ◽  
Solvent Molecules ◽  
Effective Reaction

Reactions of [Formula: see text] with the ions [Formula: see text] showed different variations of rate with solvent composition in tert-butanol/water mixtures from 0 to 100 mol% water. In pure tert-butanol solvent at 298 K the respective values of k2 (106 m3 mol−1 s−1) are 3.2, 13, and 42. The estimated value of reaction radius Rr depends on the minimum number of solvent molecules needed between [Formula: see text] and the reactant ion to attain the static values of ε of the bulk solvent used in the calculation of the Debye factor f; Rr is assumed to be larger in the alcohol-rich region than in the water-rich region, because the solvent molecules are larger. The Smoluchowski–Debye–Nernst–Einstein model is used to evaluate the effective reaction radius κRr, where κ is the probability of reaction per encounter; κRr decreases from pure tert-butanol to pure water. In the water-rich region the activation energies E2 of the efficient reactions, 11–24 kJ mol−1, are similar to EΛ0 of the reactant electrolyes, 12–23 kJ mol−1. For the inefficient reactant [Formula: see text] E2 = 30 kJ mol−1. The high values of E2 = 43–53 kJ mol−1 in pure tert-butanol solvent are attributed to a high activation energy for diffusion of [Formula: see text] in this solvent. Keywords:tert-butanol/water solvents, solvated electron, ions, reactivity, solvent effects.

scholarly journals Disruption of the self-molecular association of pentanol in binary mixtures with alkylbenzoates: a dielectric relaxation spectroscopy study

RSC Advances ◽  
2016 ◽  
Vol 6 (2) ◽  
pp. 1260-1267 ◽  
Author(s):  
Samiyara Begum ◽  
Abhinay Vardhan ◽  
Atul Chaudhary ◽  
Ranga Subramanian
Keyword(s):  
Dielectric Relaxation ◽  
Binary Mixtures ◽  
Molecular Association ◽  
The Self ◽  
Dielectric Relaxation Spectroscopy ◽  
Spectroscopy Study ◽  
Rich Region ◽  
Relaxation Study

A dielectric relaxation study of binary mixtures of associative pentanol isomers and non-associative alkylbenzoates at different mole fractions revealed that the effective dipole rotates faster in the alkylbenzoate rich region.

Compressibilities of aqueous tert-butanol in the water-rich region at 25°C: Partial molar fluctuations and mixing schemes

1999 ◽  
Vol 1 (1) ◽  
pp. 121-126 ◽  
Author(s):  
Katsutoshi Tamura ◽  
Atsushi Osaki ◽  
Yoshikata Koga
Keyword(s):  
Rich Region ◽  
Tert Butanol ◽  
Mixing Schemes

Excess partial molar enthalpies of water in water–tert-butanol mixtures

1988 ◽  
Vol 66 (12) ◽  
pp. 3171-3175 ◽  
Author(s):  
Yoshikata Koga
Keyword(s):  
Excess Free Energy ◽  
Liquid Structure ◽  
Pure Liquid ◽  
Thermodynamic Quantities ◽  
Hydrogen Bond Network ◽  
Rich Region ◽  
Tert Butanol ◽  
Chemical Potentials ◽  
Bond Network ◽  
Partial Molar Enthalpies

The excess partial molar enthalpies of H2O, HmE(H2O) in water–tert-butanol mixtures were measured at 30.00, 36.75, and 40.45°. Using the values of HmE(TBA) of the previous work (Y. Koga, Can. J. Chem. 66, 1187 (1988)), the excess (integral) molar enthalpies of the solution, HmE, were calculated at 30.00 °C, and compared with the literature values. The comparison was satisfactory. From the literature values of the excess free energy, the chemical potentials of each component were evaluated for the range, xTBA > 0.1. With the measured values of the excess partial molar enthalpies, the excess partial molar entropies were also calculated. These partial molar thermodynamic quantities and their dependence on temperature and composition clearly support the following views: (1) in the intermediate region, 0.1 < xTBA < 0.5, the system is very close to a critical demixing, and (2) in the TBA-rich region, xTBA > 0.6, TBA molecules in the solution are in almost the same environment as in the pure liquid, while H2O molecules lose the hydrogen bond network completely and are dispersed in the TBA liquid structure.

Vapour pressure of aqueous tert.-butanol in the water-rich region: transition in the mixing scheme

1990 ◽  
Vol 169 ◽  
pp. 27-38 ◽  
Author(s):  
Yoshikata Koga ◽  
Terrance Y.H. Wong ◽  
William W.Y. Siu
Keyword(s):  
Vapour Pressure ◽  
Rich Region ◽  
Tert Butanol

Observation of pseudo 10-fold symmetry in the ordered iron-zinc delta phase

1992 ◽  
Vol 50 (1) ◽  
pp. 36-37
Author(s):  
L. A. Giannuzzi ◽  
A. S. Ramani ◽  
P. R. Howell ◽  
H. W. Pickering ◽  
W. R. Bitler
Keyword(s):  
Single Phase ◽  
X Ray Diffraction ◽  
Rich Region ◽  
Average Cell ◽  
X Ray ◽  
Delta Phase ◽  
Cell Dimensions ◽  
Δ Phase ◽  
Morphological Differences ◽  
Concentration Discontinuity

The δ phase is a Zn-rich intermetallic, having a composition range of ∼ 86.5 - 92.0 atomic percent Zn, and is stable up to 665°C. The stoichiometry of the δ phase has been reported as FeZn7 and FeZn10 The deviation in stoichiometry can be attributed to variations in alloy composition used by each investigator. The structure of the δ phase, as determined by powder x-ray diffraction, is hexagonal (P63mc or P63/mmc) with cell dimensions a = 1.28 nm, c = 5.76 nm, and 555±8 atoms per unit cell. Later work suggested that the layer produced by hot-dip galvanizing should be considered as two distinct phases which are characterized by their morphological differences, namely: the iron-rich region with a compact appearance (δk) and the zinc-rich region with a columnar or palisade microstructure (δp). The sub-division of the δ phase was also based on differences in diffusion behavior, and a concentration discontinuity across the δp/δk boundary. However, work utilizing Weisenberg photographs on δ single crystals reported that the variation in lattice parameters with composition was small and hence, structurally, the δk phase and the δp phase were the same and should be thought of as a single phase, δ. Bastin et al. determined the average cell dimensions to be a = 1.28 nm and c = 5.71 nm, and suggested that perhaps some kind of ordering process, which would not be observed by x-ray diffraction, may be responsible for the morphological differences within the δ phase.

Silicification of wood-cell walls

1994 ◽  
Vol 52 ◽  
pp. 428-429
Author(s):  
S. E. Keckler ◽  
D. M. Dabbs ◽  
N. Yao ◽  
I. A. Aksay
Keyword(s):  
Electron Microscopy ◽  
Cell Wall ◽  
Cell Walls ◽  
Lignin Content ◽  
Resin Composite ◽  
Middle Lamella ◽  
Cellulose Fibers ◽  
Complex Structures ◽  
Rich Region ◽  
Inorganic Precursors

Cellular organic structures such as wood can be used as scaffolds for the synthesis of complex structures of organic/ceramic nanocomposites. The wood cell is a fiber-reinforced resin composite of cellulose fibers in a lignin matrix. A single cell wall, containing several layers of different fiber orientations and lignin content, is separated from its neighboring wall by the middle lamella, a lignin-rich region. In order to achieve total mineralization, deposition on and in the cell wall must be achieved. Geological fossilization of wood occurs as permineralization (filling the void spaces with mineral) and petrifaction (mineralizing the cell wall as the organic component decays) through infiltration of wood with inorganics after growth. Conversely, living plants can incorporate inorganics into their cells and in some cases into the cell walls during growth. In a recent study, we mimicked geological fossilization by infiltrating inorganic precursors into wood cells in order to enhance the properties of wood. In the current work, we use electron microscopy to examine the structure of silica formed in the cell walls after infiltration of tetraethoxysilane (TEOS).

Dielectric relaxation and the thermopolarization effect in crystals

1982 ◽  
Vol 137 (8) ◽  
pp. 747
Author(s):  
V.L. Gurevich
Keyword(s):  
Dielectric Relaxation

Dielectric Relaxation Studies of Silver Nanoparticles dispersed Liquid Crystal

2015 ◽  
Vol 8 (3) ◽  
pp. 2176-2188 ◽  
Author(s):  
Keisham Nanao Singh
Keyword(s):  
Activation Energy ◽  
Silver Nanoparticles ◽  
Liquid Crystal ◽  
Dielectric Relaxation ◽  
Relaxation Process ◽  
Relaxation Times ◽  
Low Frequency ◽  
Bulk Liquid ◽  
Molecular Rearrangement ◽  
Relaxation Studies

This article reports on the Dielectric Relaxation Studies of two Liquid Crystalline compounds - 7O.4 and 7O.6 - doped with dodecanethiol capped Silver Nanoparticles. The liquid crystal molecules are aligned homeotropically using CTAB. The low frequency relaxation process occurring above 1 MHz is fitted to Cole-Cole formula using the software Dielectric Spectra fit. The effect of the Silver Nanoparticles on the molecular dipole dynamics are discussed in terms of the fitted relaxation times, Cole-Cole distribution parameter and activation energy. The study indicate a local molecular rearrangement of the liquid crystal molecules without affecting the order of the bulk liquid crystal molecules but these local molecules surrounding the Silver Nanoparticles do not contribute to the relaxation process in the studied frequency range. The observed effect on activation energy suggests a change in interaction between the nanoparticles/liquid crystal molecules.

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