John P. Carini

Wide-frequency dielectric susceptibility measurements in glycerol

Data are presented on the dielectric relaxation in supercooled liquid glycerol. These data span over 14 decades in frequency from 10 −4 Hz to 2×10 10 Hz. It is found that the peak in the imaginary part of the dielectric susceptibility has a temperature dependence that can be fit with a Vogel-Fulcher form: v = v 0 exp[− A /( T − T 0 )]. The shape of the response function in the high frequency tail cannot be fit with a stretched-exponential form. However the data can be scaled onto a single master curve which has previously been shown to fit a number of other glass-forming liquids.

Solid polymer electrolytes which contain tricoordinate boron for enhanced conductivity and transference numbers

Here we report syntheses and study of composite solid polymer electrolytes (SPEs) based on a poly(ethylene glycol)-in-Li triflate material that contains an organic-inorganic composite (OIC) in which boron species are incorporated into a silica network. The structure and properties of the SPEs synthesized were characterized by scanning transmission electron microscopy (STEM), 29Si, 11B and 13C solid state NMR, differential scanning calorimetry, and impedance spectroscopy. STEM allowed assessment of OIC particles in their native environment without removal of an organic component. The Lewis acid tricoordinate boron sites formed in OIC are proposed to have a stronger interaction with triflate anions than silica sites, which results in enhanced lithium ion conductivity and Li transference numbers at optimal boron concentrations. The optimum triethyl borate (TEB) concentration also leads to formation of smaller (higher surface area) OIC particles, which expose more boron sites to triflate anions. The SPE sample prepared with 10 mol% TEB exhibited a conductivity of 4.3 × 10−5 S cm−1 and a Li transference number of 0.89, which represents nearly single-ion conductor behaviour for the salt-in-polymer–borosilicate composite.

Relaxation spectroscopies of viscous liquids

Abstract Data on supercooled liquids obtained by specific heat spectroscopy, dielectric susceptibility, ultrasonic attenuation and frequency-dependent shear modulus are reviewed. Where these different measurements have been made on the same sample, they measure the same average relaxation times. In addition, dielectric data are presented covering 13 decades in frequency. These data can all be scaled such tath, independent of temperature, they all fall on a single curve. Data for the primary relaxation of different samples can be overlaid to give a universal curve determined by only two parameters, peak frequency and width. This scaling form is different from any as yet proposed in the literature. Interesting scaling is also found when the secondary relaxation is included.

TEMPERATURE-FREQUENCY SCALING IN AMORPHOUS NIOBIUM-SILICON NEAR THE METAL-INSULATOR TRANSITION

Millimeter-wave transmission measurements have been performed in amorphous niobium-silicon alloy samples where the DC conductivity follows the critical temperature dependence

Measurements of the Complex Conductivity of NbxSi1x Alloys on the Insulating Side of the Metal-Insulator Transition

\sigma_{dc} \propto T^{1/2}

Frequency scaling of microwave conductivity in the integer quantum Hall effect minima

. The real part of the conductivity is obtained at eight frequencies in the range 87--1040 GHz for temperatures 2.6 K and above. In the quantum regime (

Hybrid composite polymer electrolytes: ionic liquids as a magic bullet for the poly(ethylene glycol)–silica network

\hbar \omega > k_B T

Ferromagnetic resonance investigations on Ga0.965Mn0.035As film

) the real part of the high-frequency conductivity has a power-law frequency dependence

Conductivity studies of quantum-critical dynamics

Re~\sigma(\omega) \propto \omega^{1/2}

Transport anisotropy and dimensional crossover in Ag/Ge multilayers

. For temperatures 16 K and below the data exhibits temperature-frequency scaling predicted by theories of dynamics near quantum-critical points.