A Phenomenological Description of the PALS Response in Glass - Forming Systems

Josef Bartoš

doi:10.4028/www.scientific.net/MSF.607.48

Paper Titles

Collisions Involving Positrons and Positronium
p.34

Positronium Thermalization Process in Nanoporous Materials and its Influence on the Shape of PALS Spectrum
p.39

S-Wave Resonances in Positron Scattering from Li and Na
p.42

Positronium in Alkanes at High Pressure of Argon and Nitrogen
p.45

A Phenomenological Description of the PALS Response in Glass - Forming Systems
p.48

Momentum Distributions of Ortho-Positronium Dependent on Electronic State at Free Volume Walls in Insulators
p.53

Free Volume and Oxygen Permeability in Polymers Related to Polymer Electrolyte Fuel Cells
p.58

Effect of Oxygen on the Free Volume Property of Poly (Ether-Urethane) Irradiated by Neutron
p.61

Seeking the Good Fitting Procedure of PALS Polymer Spectra
p.64

HomeMaterials Science ForumMaterials Science Forum Vol. 607A Phenomenological Description of the PALS...

A Phenomenological Description of the PALS Response in Glass - Forming Systems

Abstract:

A phenomenological description of the ortho-positronium (o-Ps) response from positron annihilation spectroscopy (PALS) and the dynamics from viscosity studies on two typical glass-forming compounds within the framework of the two-order parameter (TOP) model is presented. The dynamical data are accounted for by the modified Vogel – Fulcher – Tamman - Hesse (M-VFTH) equation. Subsequently, the quasi-sigmoidal course of the o-Ps lifetime, τ3, with or without the high-temperature plateau region as a function of the temperature over a wide temperature range can be described by an effective free volume version of the TOP model. This simultaneous description suggests a close relationship between the PALS response and the dynamics of supercooled liquids and seems to support the liquid - like and solid - like domain physical picture of all the three physical states of the disordered phase of the condensed systems.