Heat transport in energy materials: Study clarifies fundamental microscopic mechanisms | Canada News Media
Connect with us

Science

Heat transport in energy materials: Study clarifies fundamental microscopic mechanisms

Published

 on

Temporary formation of a defect pair in copper iodide. Although these defects only survive for a couple of picoseconds, i.e., for a trillionth of a second, they substantially influence macroscopic heat transport processes. Credit: Florian Knoop, NOMAD Laboratory

The NOMAD Laboratory researchers have recently shed light on fundamental microscopic mechanisms that can help with tailoring materials for heat insulation. This development advances the ongoing efforts to enhance energy efficiency and sustainability.

The role of heat transport is crucial in various scientific and , such as catalysis, turbine technologies, and thermoelectric heat converters that convert into electricity.

Particularly in the context of energy conservation and the development of sustainable technologies, materials with high thermal insulation capabilities are of utmost importance. These materials make it possible to retain and utilize heat that would otherwise go to waste. Therefore, improving the design of highly insulating materials is a key research objective in enabling more energy-efficient applications.

However, designing strongly heat insulators is far from trivial, despite the fact that the underlying fundamental physical laws have been known for nearly a century. At a , heat transport in semiconductors and insulators was understood in terms of the collective oscillation of the atoms around their equilibrium positions in the crystal lattice. These oscillations, called “phonons” in the field, involve a huge number of atoms in and hence cover large, almost macroscopic length- and time-scales.

In a recent joined publication in Physical Review B and Physical Review Letters, researchers from the NOMAD Laboratory at the Fritz Haber Institute have advanced the computational possibilities to compute thermal conductivities without experimental input at unprecedented accuracy. They demonstrated that for strong heat insulators the above-mentioned phonon picture is not appropriate.

Using large-scale calculations on supercomputers at of the Max Planck Society, the North-German Supercomputing Alliance, and the Jülich Supercomputing Centre, they scanned over 465 crystalline materials, for which the thermal conductivity had not been measured yet. Besides finding 28 strong thermal insulators, six of which feature an ultra-low thermal conductivity comparable to wood, this study shed light on a hitherto typically overseen mechanism that allows one to systematically lower the thermal conductivity.

“We observed the temporary formation of defect structures that massively influences the atomic motion for an extremely short period of time,” says Dr. Florian Knoop (now Linköping University), first author of both publications.

“Such effects are typically neglected in simulations, since these defects are so short-lived and so microscopically localized compared to typical heat-transport scales, that they are assumed to be irrelevant. However, the performed calculations showed that they trigger lower thermal conductivities,” adds Dr. Christian Carbogno, a senior author of the studies.

These insights may offer new opportunities to fine-tune and design thermal insulators on a nanoscale level through defect engineering, potentially contributing to advances in energy-efficient technology.

More information:
Florian Knoop et al, Anharmonicity in Thermal Insulators: An Analysis from First Principles, Physical Review Letters (2023). DOI: 10.1103/PhysRevLett.130.236301

Florian Knoop et al, Ab initio Green-Kubo simulations of heat transport in solids: Method and implementation, Physical Review B (2023). DOI: 10.1103/PhysRevB.107.224304

Provided by
Max Planck Society

 

Citation:
Heat transport in energy materials: Study clarifies fundamental microscopic mechanisms (2023, June 9)
retrieved 10 June 2023
from https://phys.org/news/2023-06-energy-materials-fundamental-microscopic-mechanisms.html

This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no
part may be reproduced without the written permission. The content is provided for information purposes only.

 

Source link

Continue Reading

Science

The body of a Ugandan Olympic athlete who was set on fire by her partner is received by family

Published

 on

 

NAIROBI, Kenya (AP) — The body of Ugandan Olympic athlete Rebecca Cheptegei — who died after being set on fire by her partner in Kenya — was received Friday by family and anti-femicide crusaders, ahead of her burial a day later.

Cheptegei’s family met with dozens of activists Friday who had marched to the Moi Teaching and Referral Hospital’s morgue in the western city of Eldoret while chanting anti-femicide slogans.

She is the fourth female athlete to have been killed by her partner in Kenya in yet another case of gender-based violence in recent years.

Viola Cheptoo, the founder of Tirop Angels – an organization that was formed in honor of athlete Agnes Tirop, who was stabbed to death in 2021, said stakeholders need to ensure this is the last death of an athlete due to gender-based violence.

“We are here to say that enough is enough, we are tired of burying our sisters due to GBV,” she said.

It was a somber mood at the morgue as athletes and family members viewed Cheptegei’s body which sustained 80% of burns after she was doused with gasoline by her partner Dickson Ndiema. Ndiema sustained 30% burns on his body and later succumbed.

Ndiema and Cheptegei were said to have quarreled over a piece of land that the athlete bought in Kenya, according to a report filed by the local chief.

Cheptegei competed in the women’s marathon at the Paris Olympics less than a month before the attack. She finished in 44th place.

Cheptegei’s father, Joseph, said that the body will make a brief stop at their home in the Endebess area before proceeding to Bukwo in eastern Uganda for a night vigil and burial on Saturday.

“We are in the final part of giving my daughter the last respect,” a visibly distraught Joseph said.

He told reporters last week that Ndiema was stalking and threatening Cheptegei and the family had informed police.

Kenya’s high rates of violence against women have prompted marches by ordinary citizens in towns and cities this year.

Four in 10 women or an estimated 41% of dating or married Kenyan women have experienced physical or sexual violence perpetrated by their current or most recent partner, according to the Kenya Demographic and Health Survey 2022.

The Canadian Press. All rights reserved.

Source link

Continue Reading

News

The ancient jar smashed by a 4-year-old is back on display at an Israeli museum after repair

Published

 on

 

TEL AVIV, Israel (AP) — A rare Bronze-Era jar accidentally smashed by a 4-year-old visiting a museum was back on display Wednesday after restoration experts were able to carefully piece the artifact back together.

Last month, a family from northern Israel was visiting the museum when their youngest son tipped over the jar, which smashed into pieces.

Alex Geller, the boy’s father, said his son — the youngest of three — is exceptionally curious, and that the moment he heard the crash, “please let that not be my child” was the first thought that raced through his head.

The jar has been on display at the Hecht Museum in Haifa for 35 years. It was one of the only containers of its size and from that period still complete when it was discovered.

The Bronze Age jar is one of many artifacts exhibited out in the open, part of the Hecht Museum’s vision of letting visitors explore history without glass barriers, said Inbal Rivlin, the director of the museum, which is associated with Haifa University in northern Israel.

It was likely used to hold wine or oil, and dates back to between 2200 and 1500 B.C.

Rivlin and the museum decided to turn the moment, which captured international attention, into a teaching moment, inviting the Geller family back for a special visit and hands-on activity to illustrate the restoration process.

Rivlin added that the incident provided a welcome distraction from the ongoing war in Gaza. “Well, he’s just a kid. So I think that somehow it touches the heart of the people in Israel and around the world,“ said Rivlin.

Roee Shafir, a restoration expert at the museum, said the repairs would be fairly simple, as the pieces were from a single, complete jar. Archaeologists often face the more daunting task of sifting through piles of shards from multiple objects and trying to piece them together.

Experts used 3D technology, hi-resolution videos, and special glue to painstakingly reconstruct the large jar.

Less than two weeks after it broke, the jar went back on display at the museum. The gluing process left small hairline cracks, and a few pieces are missing, but the jar’s impressive size remains.

The only noticeable difference in the exhibit was a new sign reading “please don’t touch.”

The Canadian Press. All rights reserved.

Source link

Continue Reading

News

B.C. sets up a panel on bear deaths, will review conservation officer training

Published

 on

 

VICTORIA – The British Columbia government is partnering with a bear welfare group to reduce the number of bears being euthanized in the province.

Nicholas Scapillati, executive director of Grizzly Bear Foundation, said Monday that it comes after months-long discussions with the province on how to protect bears, with the goal to give the animals a “better and second chance at life in the wild.”

Scapillati said what’s exciting about the project is that the government is open to working with outside experts and the public.

“So, they’ll be working through Indigenous knowledge and scientific understanding, bringing in the latest techniques and training expertise from leading experts,” he said in an interview.

B.C. government data show conservation officers destroyed 603 black bears and 23 grizzly bears in 2023, while 154 black bears were killed by officers in the first six months of this year.

Scapillati said the group will publish a report with recommendations by next spring, while an independent oversight committee will be set up to review all bear encounters with conservation officers to provide advice to the government.

Environment Minister George Heyman said in a statement that they are looking for new ways to ensure conservation officers “have the trust of the communities they serve,” and the panel will make recommendations to enhance officer training and improve policies.

Lesley Fox, with the wildlife protection group The Fur-Bearers, said they’ve been calling for such a committee for decades.

“This move demonstrates the government is listening,” said Fox. “I suspect, because of the impending election, their listening skills are potentially a little sharper than they normally are.”

Fox said the partnership came from “a place of long frustration” as provincial conservation officers kill more than 500 black bears every year on average, and the public is “no longer tolerating this kind of approach.”

“I think that the conservation officer service and the B.C. government are aware they need to change, and certainly the public has been asking for it,” said Fox.

Fox said there’s a lot of optimism about the new partnership, but, as with any government, there will likely be a lot of red tape to get through.

“I think speed is going to be important, whether or not the committee has the ability to make change and make change relatively quickly without having to study an issue to death, ” said Fox.

This report by The Canadian Press was first published Sept. 9, 2024.

The Canadian Press. All rights reserved.

Source link

Continue Reading

Trending

Exit mobile version