scholarly journals Adam-Gibbs model in the density scaling regime and its implications for the configurational entropy scaling

2015 ◽  
Vol 5 (1) ◽  
Author(s):  
Elżbieta Masiewicz ◽  
Andrzej Grzybowski ◽  
Katarzyna Grzybowska ◽  
Sebastian Pawlus ◽  
Jürgen Pionteck ◽  
...  
Keyword(s):  
Configurational Entropy ◽  
Gibbs Model

Relation between structural relaxation time and configurational entropy: A test of the Adam-Gibbs model on epoxy resins

2002 ◽  
Vol 82 (3) ◽  
pp. 339-346 ◽  
Author(s):  
S. Corezzi ◽  
D. Fioretto ◽  
S. C. Santucci ◽  
S. Capaccioli ◽  
R. Casalini ◽  
...  
Keyword(s):  
Relaxation Time ◽  
Structural Relaxation ◽  
Epoxy Resins ◽  
Configurational Entropy ◽  
Gibbs Model ◽  
Structural Relaxation Time

scholarly journals First-Principles Atomistic Thermodynamics and Configurational Entropy

2020 ◽  
Vol 8 ◽  
Author(s):  
Christopher Sutton ◽  
Sergey V. Levchenko
Keyword(s):  
First Principles ◽  
Configurational Entropy ◽  
Functional Materials ◽  
Expansion Method ◽  
Bulk Materials ◽  
Cluster Expansion Method ◽  
Particle Exchange ◽  
Properties Of Materials ◽  
Atomistic Thermodynamics ◽  
Statistical Effects

In most applications, functional materials operate at finite temperatures and are in contact with a reservoir of atoms or molecules (gas, liquid, or solid). In order to understand the properties of materials at realistic conditions, statistical effects associated with configurational sampling and particle exchange at finite temperatures must consequently be taken into account. In this contribution, we discuss the main concepts behind equilibrium statistical mechanics. We demonstrate how these concepts can be used to predict the behavior of materials at realistic temperatures and pressures within the framework of atomistic thermodynamics. We also introduce and discuss methods for calculating phase diagrams of bulk materials and surfaces as well as point defect concentrations. In particular, we describe approaches for calculating the configurational density of states, which requires the evaluation of the energies of a large number of configurations. The cluster expansion method is therefore also discussed as a numerically efficient approach for evaluating these energies.

Cobaltites as perspective thermoelectrics

2005 ◽  
Vol 886 ◽  
Author(s):  
Jiri Hejtmánek ◽  
Miroslav Veverka ◽  
Karel Knižek ◽  
Hiroyuki Fujishiro ◽  
Sylvie Hebert ◽  
...  
Keyword(s):  
Degrees Of Freedom ◽  
Phonon Scattering ◽  
Configurational Entropy ◽  
Energy Difference ◽  
Charge Carriers ◽  
Material Research ◽  
Cobalt Ions ◽  
Similar Materials ◽  
Physical Background ◽  
Open Question

AbstractThe recent material research of mixed cobalt oxides is strongly motivated by the potential of some of them to be used as chemically stable high temperature thermoelectric material. This fact together with both the theoretical and experimental ambitions to fulfill the severe criteria needed for efficient thermoelectric conversion intensified both their theoretical and experimental research. Nonetheless, despite the investigations of the prototype materials represented by 3D perovskites Ln1−xAxCoO3 (Ln = La, Y, rare-earth, A = alkaline-earth) and 2D cobaltites of NaxCoO2 type, the concise physical background of their transport and magnetic properties remain still a matter of debate. This is likely due to a fact that cobalt ions can be stabilized either in low-spin state (diamagnetic for “pure” Co3+), with filled t2g levels and empty eg states, or magnetic ones, with filled eg states. As the energy difference between respective states is due to comparable strength of crystal field and Hund's energies rather small, the thermodynamically most stable ground-state, with eventually different character of charge carriers, can be critically influenced by an interplay of additional degrees of freedom - orbital and charge. The challenge for unequivocal theoretical model represents the thermoelectric power of mixed cobaltites where, up to now, somewhat ambiguous models based either on “classical” approach, associated with diffusion of itinerant charge carriers, or more exotic - based on configurational entropy of quasi-itinerant carriers - are often used for similar materials. Simultaneously, the open question remains the assessment of the dominant mechanism of phonon scattering in 2D cobaltites.

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