Positron annihilation response and viscosity of a glass-forming system within the two-order parameter model of liquids

2008 ◽  
Vol 20 (28) ◽  
pp. 285101 ◽  
Author(s):  
J Bartoš
Keyword(s):  
Positron Annihilation ◽  
Order Parameter ◽  
Glass Forming

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

2008 ◽  
Vol 607 ◽  
pp. 48-52 ◽  
Author(s):  
Josef Bartoš
Keyword(s):  
Order Parameter ◽  
Positron Annihilation Spectroscopy ◽  
Supercooled Liquids ◽  
Phenomenological Description ◽  
Plateau Region ◽  
Glass Forming ◽  
Disordered Phase ◽  
Close Relationship ◽  
Temperature Plateau ◽  
Condensed Systems

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.

Positron annihilation study of a low-molecular-weight organic glass-forming liquid (BMMPC)

1999 ◽  
Vol 46 (6) ◽  
pp. 815-820 ◽  
Author(s):  
Sz Vass ◽  
A Patkowski ◽  
E. W Fischer ◽  
K Süvegh ◽  
A Vértes
Keyword(s):  
Molecular Weight ◽  
Positron Annihilation ◽  
Organic Glass ◽  
Low Molecular Weight ◽  
Glass Forming ◽  
Positron Annihilation Study

scholarly journals Single-order-parameter description of glass-forming liquids: A one-frequency test

2007 ◽  
Vol 126 (7) ◽  
pp. 074502 ◽  
Author(s):  
Niels L. Ellegaard ◽  
Tage Christensen ◽  
Peder Voetmann Christiansen ◽  
Niels Boye Olsen ◽  
Ulf R. Pedersen ◽  
...  
Keyword(s):  
Order Parameter ◽  
Frequency Test ◽  
Glass Forming

Electron Microscopy of Silicon Nitride-Based Ceramics

1991 ◽  
Vol 49 ◽  
pp. 926-927
Author(s):  
Gareth Thomas
Keyword(s):  
Electron Microscopy ◽  
High Temperature ◽  
Silicon Nitride ◽  
World Wide ◽  
Sintering Temperature ◽  
Liquid Phase Sintering ◽  
High Temperature Strength ◽  
Sintering Additives ◽  
Glass Forming ◽  
Dense Product

Silicon nitride and silicon nitride based-ceramics are now well known for their potential as hightemperature structural materials, e.g. in engines. However, as is the case for many ceramics, in order to produce a dense product, sintering additives are utilized which allow liquid-phase sintering to occur; but upon cooling from the sintering temperature residual intergranular phases are formed which can be deleterious to high-temperature strength and oxidation resistance, especially if these phases are nonviscous glasses. Many oxide sintering additives have been utilized in processing attempts world-wide to produce dense creep resistant components using Si3N4 but the problem of controlling intergranular phases requires an understanding of the glass forming and subsequent glass-crystalline transformations that can occur at the grain boundaries.

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