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Scientists discover new class of semiconducting entropy-stabilized materials

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Crystal structure of GeSnPbSSeTe, a semiconducting entropy-stabilized chalcogenide alloy. The yellow atoms are cations (Ge, Sn, Pb) and the blue atoms are anions (S, Se, Te). The difference in lightness corresponds to different species of the anions and cations. The configurational entropy from the disorder of both the anion and the cation sublattices stabilizes the single-phase rocksalt solid solution, as demonstrated from first-principles calculations as well as experimental synthesis and characterization. CREDIT
Logan Williams, Emmanouil Kioupakis, and Zihao Deng, Dept. of Materials Science & Engineering, University of Michigan
Crystal structure of GeSnPbSSeTe, a semiconducting entropy-stabilized chalcogenide alloy. The yellow atoms are cations (Ge, Sn, Pb) and the blue atoms are anions (S, Se, Te). The difference in lightness corresponds to different species of the anions and cations. The configurational entropy from the disorder of both the anion and the cation sublattices stabilizes the single-phase rocksalt solid solution, as demonstrated from first-principles calculations as well as experimental synthesis and characterization. CREDIT
Logan Williams, Emmanouil Kioupakis, and Zihao Deng, Dept. of Materials Science & Engineering, University of Michigan

Abstract:
Semiconductors are important materials in numerous functional applications such as digital and analog electronics, solar cells, LEDs, and lasers. Semiconducting alloys are particularly useful for these applications since their properties can be engineered by tuning the mixing ratio or the alloy ingredients. However, the synthesis of multicomponent semiconductor alloys has been a big challenge due to thermodynamic phase segregation of the alloy into separate phases. Recently, University of Michigan researchers Emmanouil (Manos) Kioupakis and Pierre F. P. Poudeu, both in the Materials Science and Engineering Department, utilized entropy to stabilize a new class of semiconducting materials, based on GeSnPbSSeTe high-entropy chalcogenide alloys,[1] a discovery that paves the way for wider adoption of entropy-stabilized semiconductors in functional applications. Their article, “Semiconducting high-entropy chalcogenide alloys with ambi-ionic entropy stabilization and ambipolar doping” was recently published in the journal Chemistry of Materials.

Scientists discover new class of semiconducting entropy-stabilized materials


Ann Arbor, MI | Posted on July 31st, 2020

Entropy, a thermodynamic quantity that quantifies the degree of disorder in a material, has been exploited to synthesize a vast array of novel materials by mixing eachcomponent in an equimolar fashion, from high-entropy metallic alloys to entropy-stabilized ceramics. Despite having a large enthalpy of mixing, these materials can surprisingly crystalize in a single crystal structure, enabled by the large configurational entropy in the lattice. Kioupakis and Poudeu hypothesized that this principle of entropy stabilization can be applied to overcome the synthesis challenges of semiconducting alloys that prefer to segregation into thermodynamically more stable compounds. They tested their hypothesis on a 6-component II-VI chalcogenide alloy derived from the PbTe structure by mixing Ge, Sn, and Pb on the cation site, and S, Se, and Te on the anion site.

Using high throughput first-principles calculations, Kioupakis uncovered the complex interplay between the enthalpy and entropy in GeSnPbSSeTe high-entropy chalcogenide alloys. He found that the large configurational entropy from both anion and cation sublattices stabilizes the alloys into single-phase rocksalt solid solutions at the growth temperature. Despite being metastable at room temperature, these solid solutions can be preserved by fast cooling under ambient conditions. Poudeu later verified the theory predictions by synthesizing the e

quimolar composition (Ge1/3Sn1/3Pb1/3S1/3Se1/3Te1/3) by a two-step solid-state reaction followed by fast quenching in liquid nitrogen. The synthesized power showed well-defined XRD patterns corresponding to a pure rocksalt structure. Furthermore, they observed reversible phase transition between single-phase solid solution and multiple-phase segregation from DSC analysis and temperature dependent XRD, which is a key feature of entropy stabilization.

What makes high-entropy chalcogenide intriguing is their functional properties. Previously discovered high-entropy materials are either conducting metals or insulating ceramics, with a clear dearth in the semiconducting regime. Kioupakis and Poudeu found that. the equimolar GeSnPbSSeTe is an ambipolarly dopable semiconductor, with evidence from a calculated band gap of 0.86 eV and sign reversal of the measured Seebeck coefficient upon p-type doping with Na acceptors and n-type doping with Bi donors. The alloy also exhibits an ultralow thermal conductivity that is nearly independent of temperature. These fascinating functional properties make GeSnPbSSeTe a promising new material to be deployed in electronic, optoelectronic, photovoltaic, and thermoelectric devices.

Entropy stabilization is a general and powerful method to realize a vast array of materials compositions. The discovery of entropy stabilization in semiconducting chalcogenide alloys by the team at UM is only the tip of the iceberg that can pave the way for novel functional applications of entropy-stabilized materials.

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This study was supported by the National Science Foundation through Grant No. DMR-1561008 (first-principles calculations, synthesis, and characterization) and the Department of Energy, Office of Basic Energy Sciences under Award # DE-SC-00018941 (electronic and thermal transport measurements). The DFT calculations used resources of the National Energy Research Scientific Computing (NERSC) Center, a DOE Office of Science User Facility supported under Contract No. DE-AC02-05CH11231.Related conference presentation:

Zihao Deng, Alan Olvera, Joseph Casamento, Juan Lopez, Logan Williams, Ruiming Lu, Guangsha Shi, Pierre F. P. Poudeu, and Emmanouil Kioupakis. Computational prediction and experimental discovery of semiconducting high-entropy chalcogenide alloys, MRS Fall Meeting 2019, EL04.01.05

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For more information, please click here

Contacts:
Emmanouil (Manos) Kioupakis
734-945-4456

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Tao Treasures LLC DBA Nanobiofab, a minority woman-owned nanotech startup in the Frederick Innovative Technology Center, Inc. (FITCI), is helping medical mannequins tell doctors where it hurts. The company, which creates revolutionary million-scale nanomaterial used in applications ranging from routine health monitoring to cancer detection, is working with West Virginia University (WVU) to improve clinical simulators. The million-dollar effort, initiated through the Defense Health Agency Small Business Innovation Research (SBIR) program, starts in September at Nanobiofab (Frederick, MD) and the David and Jo Ann Shaw Center for Simulation Training and Education for Patient Safety (STEPS) at WVU in Morgantown, WV.

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For more information on Nanobiofab, visit Nanobiofab.com or FITCI.org.

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STid SPECTRE nano Reader Accelerates Car Park Access Control with…

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STid launches Spectre nano reader

Our SPECTRE nano reader offers a faster entry/exit process and simple, hands-free use with top end-to-end security for hospitals, government agencies, universities and more.

STid, creator of the world’s most awarded access control reader, announced today it has set a new standard in car park access control and simplified visitor management with its new SPECTRE nano reader. The multi-technology reader quickly recognizes employees, visitors, vendors, and their vehicles – simultaneously – for smooth, hands-free access control without compromising security.

Easy to use, “all terrain” reader

The next generation, hands-free reader increases speed of entry for anyone – or anything – on two feet, two wheels, four wheels or a whole fleet. It reads windshield tags, key fobs, cards, smartphones, or wearables using UHF and Bluetooth® to leverage end-user preferences for easier adoption. It is also part of the STid Mobile ID® ecosystem, which turns smartphones into virtual cards for both vehicle and pedestrian access control.

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For more information contact: [email protected]

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AerNos AerHome

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# # #

About AerNos

AerNos, Inc. develops application-specific nano gas sensors based on its breakthrough and proprietary AerN2S™ Technology to detect harmful gases in the environment. AerNos nano gas sensors are designed to be easily integrated into consumer and commercial product lines, such as standalone monitoring devices, non-stationary devices (e.g., drones, industrial robots, construction equipment), modes of transportation, wearables, smartphones, and IoT. AerHome™, AerBand™, AerCity™, AerHome™, and AerNos™ are trademarks of AerNos, Inc. For more information, please visit http://www.AerNos.com. You may also contact us at [email protected]

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Powercast’s RF Wireless Power Technology Awarded for Global…

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Powercast aims to save millions of one-time-use batteries from entering landfills yearly

Powercast’s RF Wireless Power Technology Wins Global Sustainability Award for Reducing Battery Use, E-Waste

We’re partnering with many manufacturers to create wirelessly rechargeable devices that keep batteries out of landfills. Charles Goetz, CEO of Powercast.

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About Powercast

Powercast is the established leader in RF wireless power. Since its founding in 2003, Powercast has led the industry in RF wireless power innovations and applications that meet FCC and other global standards. Powercast’s wireless power technologies eliminate or reduce the need for wires and batteries, working at distances up to 80 feet. With millions of units shipped, Powercast is led by a team with deep expertise in design, engineering, and prototyping, and with extensive commercial success in both industrial and consumer applications. With more than 100 customers and partner companies around the world, Powercast leads the RF wireless power market with 63 early and fundamental patents worldwide and 34 patents pending. For more information, visit http://www.powercastco.com.

About Business Intelligence Group

The Business Intelligence Group was founded with the mission of recognizing true talent and superior performance in the business world. Unlike other industry award programs, business executives—those with experience and knowledge—judge the programs. The organization’s proprietary and unique scoring system selectively measures performance across multiple business domains and then rewards those companies whose achievements stand above those of their peers.

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