Subscribe to our free daily newsletters
. 24/7 Space News .




Subscribe to our free daily newsletters



TECH SPACE
Feel the heat, one touch a time
by Staff Writers
Beijing, China (SPX) Jul 10, 2017


This image shows quantitative mapping of thermal conductivities; (a) changes in the probe resistance induced by samples with different thermal conductivities; and mappings of (b) resistance change and (c) corresponding thermal conductivities in Yb0.7Co4Sb12; (d) line scan of resistance change across an interface between phase 1 and phase 3. Credit Science China Press

In the last two decades, engineering the microstructures and compositions at the nanoscale has resulted in substantial advances in materials properties, and this is particularly so for thermoelectric materials, which has seen their figure of merit ZT more than doubled since 2000 largely due to nanostructuring.

These materials are promising for recovery of tremendous waste heat produced during industrial production and in our daily life, and they can enable effective solid state thermal management such as heating and cooling as well.

Thermoelectric figure of merit ZT, which governs the conversion efficiency, thus is critical, yet very little is known about the local thermoelectric properties such as thermal conductivity that ultimately determine the macroscopic ZT, other than theoretical analysis. While the composition, phase, and microstructure of a material can now be mapped with atomic resolution, the properties such as thermal conductivity are usually measured at the macroscopic scale.

Now this missing link between microstructure and macroscopic property of material is connected by Nasr Esfahani and his colleagues from the University of Washington and Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences. This work, entitled Quantitative Nanoscale Mapping of Three-Phase Thermal Conductivities in Filled Skutterudites via Scanning Thermal Microscopy, was published in National Science Review.

The team used a technique known as scanning thermal microscopy (SThM) to study a three-phase thermoelectric material. A cantilever equipped with a microfabricated heater and a sharp tip was used to probe the sample, very much in a similar way as human finger touching the surface.

The heat dissipation through the sample reduces the temperature of the heater and changes its resistance, which can be accurately measured. Regions with higher thermal conductivity results in higher temperature drop, making it possible to differentiate materials with different thermal conductivities.

Since the tip radius is as small as 10 nanometers, spatial resolution orders of magnitude higher than conventional technique can be realized. The team then carried out detailed finite element computation to simulate the local heat transfer process, calibrated by a range of reference samples with known thermal conductivities. This make it possible for them to determine the local thermal conductivity quantitatively, with a spatial resolution better than 100 nanometer.

As seen in Figure 1 in their results, there is good agreement between finite element simulation and experimental measurement of resistance change of the probe upon touching samples with different thermal conductivities, and thus the spatial mapping of thermal conductivity can be derived from the experimentally measured resistance mapping.

It is particularly interesting to note that thermal conductivity variation across the interface is nicely captured, and unlike previous SThM studies, the thermal image show no crosstalk with topography, but nicely correlate with the microstructural composition (Figure 2).

As noted by Prof. Lidong Zhao of Beihang University and Prof. Mercouri G. Kanatzidis of Northwestern University, two leading material scientists in thermoelectrics, "This method reported by Esfahani et al. is a valuable advance in thermoelectric materials characterization, and if can be widely adopted it will add to the toolbox of characterization techniques used in searching for ever higher performance thermoelectric materials."

Research Report: Quantitative nanoscale mapping of three-phase thermal conductivities in filled skutterudites via scanning thermal microscopy

TECH SPACE
Engineers find way to evaluate green roofs
Champaign IL (SPX) Jul 10, 2017
Green infrastructure is an attractive concept, but there is concern surrounding its effectiveness. Researchers at the University of Illinois at Urbana-Champaign are using a mathematical technique traditionally used in earthquake engineering to determine how well green infrastructure works and to communicate with urban planners, policymakers and developers. Green roofs are flat, vegetated s ... read more

Related Links
Science China Press
Space Technology News - Applications and Research


Thanks for being here;
We need your help. The SpaceDaily news network continues to grow but revenues have never been harder to maintain.

With the rise of Ad Blockers, and Facebook - our traditional revenue sources via quality network advertising continues to decline. And unlike so many other news sites, we don't have a paywall - with those annoying usernames and passwords.

Our news coverage takes time and effort to publish 365 days a year.

If you find our news sites informative and useful then please consider becoming a regular supporter or for now make a one off contribution.

SpaceDaily Contributor
$5 Billed Once


credit card or paypal
SpaceDaily Monthly Supporter
$5 Billed Monthly


paypal only

Comment using your Disqus, Facebook, Google or Twitter login.

Share this article via these popular social media networks
del.icio.usdel.icio.us DiggDigg RedditReddit GoogleGoogle

TECH SPACE
Dutch project tests floating cities to seek more space

Creating Trends in Space: An Interview with NanoRacks CEO Jeffrey Manber

Trump offers bold space goals but fills in few details

Liftoff for Trump's bold space plans may have to wait

TECH SPACE
Aerojet Rocketdyne tests Advanced Electric Propulsion System

After two delays, SpaceX launches broadband satellite for IntelSat

Spiky ferrofluid thrusters can move satellites

On the road to creating an electrodeless spacecraft propulsion engine

TECH SPACE
Mars surface 'more uninhabitable' than thought: study

Mars Rover Opportunity continuing science campaign at Perseverance Valley

The Niagara Falls of Mars once flowed with lava

Russian Devices for ExoMars Mission to Be Ready in Fall 2017

TECH SPACE
China develops sea launches to boost space commerce

Chinese satellite Zhongxing-9A enters preset orbit

Chinese Space Program: From Setback, to Manned Flights, to the Moon

Chinese Rocket Fizzles Out, Puts Other Launches on Hold

TECH SPACE
Iridium Poised to Make Global Maritime Distress and Safety System History

100M Pound boost for UK space sector

HTS Capacity Lease Revenues to Reach More Than $6 Billion by 2025

SES Transfers Capacity from AMC-9 Satellite Following Significant Anomaly

TECH SPACE
Sorting complicated knots

Engineers find way to evaluate green roofs

Nature-inspired material uses liquid reinforcement

Feel the heat, one touch a time

TECH SPACE
Odd planetary system around fast-spinning star doesn't quite fit existing models of planet formation

Evidence discovered for two distinct giant planet populations

A cosmic barbecue: Researchers spot 60 new 'hot Jupiter' candidates

Re-making planets after star-death

TECH SPACE
NASA spacecraft to fly over Jupiter's Great Red Spot

New Mysteries Surround New Horizons' Next Flyby Target

Mid-infrared images from the Subaru telescope extend Juno spacecraft discoveries

Earth-based Views of Jupiter to Enhance Juno Flyby




Memory Foam Mattress Review
Newsletters :: SpaceDaily :: SpaceWar :: TerraDaily :: Energy Daily
XML Feeds :: Space News :: Earth News :: War News :: Solar Energy News






The content herein, unless otherwise known to be public domain, are Copyright 1995-2017 - Space Media Network. All websites are published in Australia and are solely subject to Australian law and governed by Fair Use principals for news reporting and research purposes. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA news reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. All articles labeled "by Staff Writers" include reports supplied to Space Media Network by industry news wires, PR agencies, corporate press officers and the like. Such articles are individually curated and edited by Space Media Network staff on the basis of the report's information value to our industry and professional readership. Advertising does not imply endorsement, agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement