Recognition of a new permittivity function for glycerol by the use of the eigen-coordinates method

Measurements of real and imaginary parts of the relative complex permittivity of glycerol were carried out in the frequency range 1 mHz-1 MHz at different temperatures between 188 and 263 K. The permittivity data have been analyzed thoroughly by a new data curve-fitting approach that involves the so-called eigen-coordinates method in conjunction with a separation procedure and the inverse permittivity formulas. A new single permittivity function, based on the so-called recap element picture for a self-similar (fractal) structure, has been recognized to describe well such data over the entire frequency range studied. The recognized dielectric function enabled us to infer an electrical equivalent-circuit network for the glycerol sample studied that involves a series combination of two recap elements, reflecting the existence of two different dielectric relaxation processes in glycerol. The temperature dependence of the relaxation times τ1(T) and τ2(T) entering into the identified permittivity function was found to obey nearly an Arrhenius behaviour with activation energies E1 ≈ 114 kJ/mol and E2 ≈ 94 kJ/mol. The recognized permittivity function can be justified by presuming that the processes represented by the recap elements characterized by the parameters (ν1, τ1, E1) and (ν2, τ2, E2) are linked to 'donor-like' and 'acceptor-like' charges formed from the infinite hydroxyl hydrogen bonds. © 2002 Elsevier Science B.V. All rights reserved

Recognition of a new permittivity function for glycerol by the use of the eigen-coordinates method

Measurements of real and imaginary parts of the relative complex permittivity of glycerol were carried out in the frequency range 1 mHz-1 MHz at different temperatures between 188 and 263 K. The permittivity data have been analyzed thoroughly by a new data curve-fitting approach that involves the so-called eigen-coordinates method in conjunction with a separation procedure and the inverse permittivity formulas. A new single permittivity function, based on the so-called recap element picture for a self-similar (fractal) structure, has been recognized to describe well such data over the entire frequency range studied. The recognized dielectric function enabled us to infer an electrical equivalent-circuit network for the glycerol sample studied that involves a series combination of two recap elements, reflecting the existence of two different dielectric relaxation processes in glycerol. The temperature dependence of the relaxation times τ1(T) and τ2(T) entering into the identified permittivity function was found to obey nearly an Arrhenius behaviour with activation energies E1 ≈ 114 kJ/mol and E2 ≈ 94 kJ/mol. The recognized permittivity function can be justified by presuming that the processes represented by the recap elements characterized by the parameters (ν1, τ1, E1) and (ν2, τ2, E2) are linked to 'donor-like' and 'acceptor-like' charges formed from the infinite hydroxyl hydrogen bonds. © 2002 Elsevier Science B.V. All rights reserved

Recognition of a new permittivity function for glycerol by the use of the eigen-coordinates method

Measurements of real and imaginary parts of the relative complex permittivity of glycerol were carried out in the frequency range 1 mHz-1 MHz at different temperatures between 188 and 263 K. The permittivity data have been analyzed thoroughly by a new data curve-fitting approach that involves the so-called eigen-coordinates method in conjunction with a separation procedure and the inverse permittivity formulas. A new single permittivity function, based on the so-called recap element picture for a self-similar (fractal) structure, has been recognized to describe well such data over the entire frequency range studied. The recognized dielectric function enabled us to infer an electrical equivalent-circuit network for the glycerol sample studied that involves a series combination of two recap elements, reflecting the existence of two different dielectric relaxation processes in glycerol. The temperature dependence of the relaxation times τ1(T) and τ2(T) entering into the identified permittivity function was found to obey nearly an Arrhenius behaviour with activation energies E1 ≈ 114 kJ/mol and E2 ≈ 94 kJ/mol. The recognized permittivity function can be justified by presuming that the processes represented by the recap elements characterized by the parameters (ν1, τ1, E1) and (ν2, τ2, E2) are linked to 'donor-like' and 'acceptor-like' charges formed from the infinite hydroxyl hydrogen bonds. © 2002 Elsevier Science B.V. All rights reserved

Recognition of a new permittivity function for glycerol by the use of the eigen-coordinates method

Measurements of real and imaginary parts of the relative complex permittivity of glycerol were carried out in the frequency range 1 mHz-1 MHz at different temperatures between 188 and 263 K. The permittivity data have been analyzed thoroughly by a new data curve-fitting approach that involves the so-called eigen-coordinates method in conjunction with a separation procedure and the inverse permittivity formulas. A new single permittivity function, based on the so-called recap element picture for a self-similar (fractal) structure, has been recognized to describe well such data over the entire frequency range studied. The recognized dielectric function enabled us to infer an electrical equivalent-circuit network for the glycerol sample studied that involves a series combination of two recap elements, reflecting the existence of two different dielectric relaxation processes in glycerol. The temperature dependence of the relaxation times τ1(T) and τ2(T) entering into the identified permittivity function was found to obey nearly an Arrhenius behaviour with activation energies E1 ≈ 114 kJ/mol and E2 ≈ 94 kJ/mol. The recognized permittivity function can be justified by presuming that the processes represented by the recap elements characterized by the parameters (ν1, τ1, E1) and (ν2, τ2, E2) are linked to 'donor-like' and 'acceptor-like' charges formed from the infinite hydroxyl hydrogen bonds. © 2002 Elsevier Science B.V. All rights reserved

The Glass Transition and Dielectric Secondary Relaxation of Fructose-Water Mixtures

Broad-band dielectric measurements for fructose-water mixtures with fructose concentrations between 70.0 and 94.6 wt% were carried out in the frequency range of 2 mHz to 20 GHz in the temperature range of -70 to 45 degrees C. Two relaxation processes, the alpha process at lower frequency and the secondary beta process at higher frequency, were observed. The dielectric relaxation time of the alpha process was 100 s at the glass transition temperature, T(g), determined by differential scanning calorimetry (DSC). The relaxation time and strength of the beta process changed from weaker temperature dependences of below T(g) to a stronger one above T(g). These changes in behaviors of the beta process in fructose-water mixtures upon crossing the T(g) of the mixtures is the same as that found for the secondary process of water in various other aqueous mixtures with hydrogen-bonding molecular liquids, polymers, and nanoporous systems. These results lead to the conclusion that the primary a process of fructose-water mixtures results from the cooperative motion of water and fructose molecules, and the secondary beta process is the Johari -Goldstein process of water in the mixture. At temperatures near and above T(g) where both the alpha and the beta processes were observed and their relaxation times, tau(alpha) and tau(beta), were determined in some mixtures, the ratio tau(alpha)/tau(beta) is in accord with that predicted by the coupling model. Fixing tau(alpha) at 100 s, the ratio tau(alpha)/tau(beta) decreases with decreasing concentration of fructose in the mixtures. This trend is also consistent with that expected by the coupling model from the decrease of the intermolecular coupling parameter upon decreasing fructose concentration

Electronic structure and polar catastrophe at the surface of Lix CoO2 studied by angle-resolved photoemission spectroscopy

We report an angle-resolved photoemission spectroscopy (ARPES) study of LixCoO2 single crystals which have a hole-doped CoO2 triangular lattice. Similar to NaxCoO2, the Co 3d a(1g) band crosses the Fermi level with strongly renormalized band dispersion while the Co 3d e '(g) bands are fully occupied in LixCoO2 (x = 0.46 and 0.71). At x = 0.46, the Fermi surface area is consistent with the bulk hole concentration indicating that the ARPES result represents the bulk electronic structure. On the other hand, at x = 0.71, the Fermi surface area is larger than the expectation which can be associated with the inhomogeneous distribution of Li reported in the previous scanning tunneling microscopy study by Iwaya et al. [Phys. Rev. Lett. 111, 126104 (2013)]. However, the Co 3d peak is systematically shifted towards the Fermi level with hole doping excluding phase separation between hole rich and hole poor regions in the bulk. Therefore, the deviation of the Fermi surface area at x = 0.71 can be attributed to hole redistribution at the surface avoiding polar catastrophe. The bulk Fermi surface of Co 3d a(1g) is very robust around x = 0.5 even in the topmost CoO2 layer due to the absence of the polar catastrophe