Thumbnail
Access Restriction
Open

Author Macdonald, J. Ross
Sponsorship (US)
Source United States Department of Energy Office of Scientific and Technical Information
Content type Text
Publisher The American Physical Society
Language English
Subject Keyword MATERIALS SCIENCE ♦ DIELECTRIC MATERIALS ♦ PHYSICS ♦ RELAXATION ♦ SHAPE ♦ TRANSPORT
Abstract Problems with scaling of conductive-system experimental M{sub dat}{sup {double_prime}}({omega}) and {sigma}{sub dat}{prime}({omega}) data are considered and resolved by dispersive-relaxation-model fitting and comparison. Scaling is attempted for both synthetic and experimental M{sup {double_prime}}({omega}) data sets. A crucial element in all experimental frequency-response data is the influence of the high-frequency-limiting dipolar-and-vibronic dielectric constant {var_epsilon}{sub D{infinity}}, often designated {var_epsilon}{sub {infinity}}, and not related to ionic transport. It is shown that {var_epsilon}{sub D{infinity}} precludes scaling of M{sub dat}{sup {double_prime}}({omega}) for ionic materials when the mobile-charge concentration varies. When the effects of {var_epsilon}{sub D{infinity}} are properly removed from the data, however, such scaling is viable. Only the {sigma}{prime}({omega}) and {var_epsilon}{sup {double_prime}}({omega}) parts of immittance response are uninfluenced by {var_epsilon}{sub D{infinity}}. Thus, scaling is possible for experimental {sigma}{prime}({omega}) data sets under concentration variation if the shape parameter of a well-fitting model remains constant and if any parts of the response not associated with bulk ionic transport are eliminated. Comparison between the predictions of the original-modulus-formalism (OMF) response model of 1972{endash}1973 and a corrected version of it that takes proper account of {var_epsilon}{sub D{infinity}}, the corrected modulus formalism (CMF), demonstrates that the role played by {var_epsilon}{sub D{infinity}} (or {var_epsilon}{sub {infinity}}) in the OMF is incorrect. Detailed fitting of data for three different ionic glasses using a Kohlrausch{endash}Williams{endash}Watts response model, the KWW{sub 1}, for OMF and CMF analysis clearly demonstrates that the OMF leads to inconsistent shape-parameter ({beta}{sub 1}) estimates and the CMF does not. The CMF KWW{sub 1} model is shown to subsume, correct, and generalize the recent disparate scaling/fitting approaches of Sidebottom, Leon, Roling, and Ngai. {copyright} 2001 American Institute of Physics.
ISSN 00218979
Educational Use Research
Learning Resource Type Article
Publisher Date 2001-07-01
Publisher Place United States
Journal Journal of Applied Physics
Volume Number 90
Issue Number 1


Open content in new tab

   Open content in new tab