In:
Journal of Materials Research, Springer Science and Business Media LLC, Vol. 12, No. 2 ( 1997-02), p. 474-479
Abstract:
This paper presents a new form of linear free energy (LFE) relationship for diffusive mass transport in oxides and other binary compounds. The relationship applies to a family of related compounds. For a given substance, i , solid-state diffusivity is related to the equilibrium constant K i or the free energy of transformation, , via a transfer coefficient γ, through the expression ln D i = γ ln K i + constant . The system investigated here is the series of suboxide intermediates of vanadium pentoxide formed during temperature-programmed synthesis of vanadium nitride. The value of γ for this series is 0.27. The diffusivity values are determined by fitting a mathematical model to the experimental data. Diffusivity data are presented graphically in contour diagrams which correlate pre-exponential values, activation energies, particle sizes, and heating rates used in the temperature-programmed syntheses. An Evans–Polanyi linear relation, , relating activation energy, E i , to enthalpy change of transformation, , via a transfer coefficient α = 0.53, is also shown to exist for the above system. The discrepancy between α and γ is resolved by using the Horiuti concept of the stoichiometric number of the rate-determining step.
Type of Medium:
Online Resource
ISSN:
0884-2914
,
2044-5326
DOI:
10.1557/JMR.1997.0069
Language:
English
Publisher:
Springer Science and Business Media LLC
Publication Date:
1997
detail.hit.zdb_id:
54876-5
detail.hit.zdb_id:
2015297-8
