Skip to main content Accessibility help
×
Home
Hostname: page-component-55597f9d44-2qt69 Total loading time: 0.367 Render date: 2022-08-08T07:34:43.524Z Has data issue: true Feature Flags: { "shouldUseShareProductTool": true, "shouldUseHypothesis": true, "isUnsiloEnabled": true, "useRatesEcommerce": false, "useNewApi": true } hasContentIssue true

Article contents

Energy Focus: Thermoelectrics and effective medium theory–a recipe for innovation

Published online by Cambridge University Press:  13 January 2015

Abstract

Type
Other
Copyright
Copyright © Materials Research Society 2015 

Effective medium theory is typically employed to predict the macroscopic properties of multiphase composite materials, based on a knowledge of the properties of the individual components. Recently, however, a research team from the California Institute of Technology and the University of Southern California for the first time applied the theory to the opposite problem: calculating conductivity and mobility of individual phases from the overall bulk properties of Cu1.97Ag0.03Se, a multiphase thermo-electric composite material.

Thermoelectric materials transform electricity into heat and vice versa. Compared to traditional heating and cooling systems, thermoelectrics can be used to heat or cool on a smaller or more localized scale (think “car seats”). In most cases thermoelectric materials possess a complex stoichiometry. Phase-pure syntheses can be challenging and the presence of impurity phases makes it difficult to accurately assess the properties of the thermoelectric target material.

Under the lead of G. Jeffrey Snyder, the researchers studied the multiphase composite Cu1.97Ag0.03Se with magnetic-field dependent resistivity measurements and analyzed the results using effective medium theory.

As recently reported in Applied Physics Letters (DOI: 10.1063/1.4897435), both the magnetoresistance and the Hall effect of the different phases within Cu1.97Ag0.03Se exhibit unique dependence on an applied magnetic field, which makes them identifiable to the researchers. One impurity phase, for example, exists at temperatures below 390 K and displays high mobility values, thereby dominating the transport properties of the composite material despite taking up only 3% of the total sample volume.

“Cu1.97Ag0.03Se is a useful thermoelectric, which is intended to be used above the superionic phase transition temperature, at 390 K, where the material consists of a single phase,” said Snyder. “The research we carried out for this paper below the superionic phase transition temperature is more of an academic exercise, demonstrating that we can determine the contributions of individual phases to bulk properties. It is really interesting to see how even a small impurity phase can dominate the overall behavior of a composite material.”

Understanding the contribution of individual phases to the overall properties of thermoelectric composite materials will guide researchers in their quest to optimize this class of materials and to further the implementation of thermoelectrics in everyday applications. The newly discovered use of effective medium theory will certainly play an important role in future studies, as Tristan W. Day, who is the first author of this study, confirmed.

“What we have learned in this study, with regard to using effective medium theory in reverse, is useful for studying other composite materials as well. The methodology can be applied to our work on organic/inorganic thermoelectrics, for example,” said Day.

You have Access

Save article to Kindle

To save this article to your Kindle, first ensure coreplatform@cambridge.org is added to your Approved Personal Document E-mail List under your Personal Document Settings on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part of your Kindle email address below. Find out more about saving to your Kindle.

Note you can select to save to either the @free.kindle.com or @kindle.com variations. ‘@free.kindle.com’ emails are free but can only be saved to your device when it is connected to wi-fi. ‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.

Find out more about the Kindle Personal Document Service.

Energy Focus: Thermoelectrics and effective medium theory–a recipe for innovation
Available formats
×

Save article to Dropbox

To save this article to your Dropbox account, please select one or more formats and confirm that you agree to abide by our usage policies. If this is the first time you used this feature, you will be asked to authorise Cambridge Core to connect with your Dropbox account. Find out more about saving content to Dropbox.

Energy Focus: Thermoelectrics and effective medium theory–a recipe for innovation
Available formats
×

Save article to Google Drive

To save this article to your Google Drive account, please select one or more formats and confirm that you agree to abide by our usage policies. If this is the first time you used this feature, you will be asked to authorise Cambridge Core to connect with your Google Drive account. Find out more about saving content to Google Drive.

Energy Focus: Thermoelectrics and effective medium theory–a recipe for innovation
Available formats
×
×

Reply to: Submit a response

Please enter your response.

Your details

Please enter a valid email address.

Conflicting interests

Do you have any conflicting interests? *