Local vs. global order in GeTe-based phase-change alloys

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F00216275%3A25310%2F12%3A39896017" target="_blank" >RIV/00216275:25310/12:39896017 - isvavai.cz</a>

Výsledek na webu

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DOI - Digital Object Identifier

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Jazyk výsledku

angličtina

Název v původním jazyce

Local vs. global order in GeTe-based phase-change alloys

Popis výsledku v původním jazyce

In the low temperature GeTe crystalline phase, Ge and Te atoms are sixfold coordinated by each other with subsets of three shorter 2.83 ? and three longer 3.15 ? bonds often described as a Peierl distortion. Based on Bragg-diffraction studies, it was concluded that rhombohedral GeTe undergoes a displacive ferroelectric-paralectric transition with the Curie temperature,Tc, around 705 K transforming to the rocksalt structure (Fm3m). Alloying of GeTe with Sb2Te3 generates vacancies which, together with newSb-Te bonds, gradually decreases the value of the Curie temperature. When Sb2Te3 exceeds 0.137 in (GeTe)x(Sb2Te3)1?x, only the cubic phase can be observed using the Bragg diffraction2. Here, we demonstrate through the combined use of x-ray Bragg diffraction and EXAFS that although the global structure of Ge-Sb-Te undergoes a rhombohedral to rock-salt-like structural transition, locally the material maintains a 3 + 3 bond length splitting configuration at temperatures above Tc, that is,

Název v anglickém jazyce

Local vs. global order in GeTe-based phase-change alloys

Popis výsledku anglicky

In the low temperature GeTe crystalline phase, Ge and Te atoms are sixfold coordinated by each other with subsets of three shorter 2.83 ? and three longer 3.15 ? bonds often described as a Peierl distortion. Based on Bragg-diffraction studies, it was concluded that rhombohedral GeTe undergoes a displacive ferroelectric-paralectric transition with the Curie temperature,Tc, around 705 K transforming to the rocksalt structure (Fm3m). Alloying of GeTe with Sb2Te3 generates vacancies which, together with newSb-Te bonds, gradually decreases the value of the Curie temperature. When Sb2Te3 exceeds 0.137 in (GeTe)x(Sb2Te3)1?x, only the cubic phase can be observed using the Bragg diffraction2. Here, we demonstrate through the combined use of x-ray Bragg diffraction and EXAFS that although the global structure of Ge-Sb-Te undergoes a rhombohedral to rock-salt-like structural transition, locally the material maintains a 3 + 3 bond length splitting configuration at temperatures above Tc, that is,

Druh

O - Ostatní výsledky

CEP obor

CA - Anorganická chemie

OECD FORD obor

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Projekt

<a href="/cs/project/EE2.3.20.0254" target="_blank" >EE2.3.20.0254: Výzkumný tým pro pokročilé nekrystalické materiály</a><br>

Návaznosti

P - Projekt vyzkumu a vyvoje financovany z verejnych zdroju (s odkazem do CEP)

Rok uplatnění

2012

Kód důvěrnosti údajů

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů