Elusive Valence Transition in Mixed-Valence Sesquioxide Cs4O6

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F00216208%3A11320%2F19%3A10401678" target="_blank" >RIV/00216208:11320/19:10401678 - isvavai.cz</a>

Výsledek na webu

<a href="https://verso.is.cuni.cz/pub/verso.fpl?fname=obd_publikace_handle&handle=IUc~2h-dQb" target="_blank" >https://verso.is.cuni.cz/pub/verso.fpl?fname=obd_publikace_handle&handle=IUc~2h-dQb</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1021/acs.inorgchem.9b02122" target="_blank" >10.1021/acs.inorgchem.9b02122</a>

Jazyk výsledku

angličtina

Název v původním jazyce

Elusive Valence Transition in Mixed-Valence Sesquioxide Cs4O6

Popis výsledku v původním jazyce

Cs4O6 is a mixed-valence molecular oxide with a cubic structure, comprising valency-delocalized O-2(4/3-) units and with properties highly sensitive to cooling protocols. Here we use neutron powder diffraction to authenticate that, while upon deep quenching the cubic phase is kinetically arrested down to cryogenic temperatures, ultraslow cooling results in an incomplete structural transition to a contracted tetragonal phase. Two dioxygen anions in a 1:2 ratio are identified, providing evidence that the transition is accompanied by charge and orbital order and stabilizes a Robin-Day Class II mixed-valence state, comprising O-2(2-) and O-2(-) anions. The phenomenology of the phase change is consistent with that of a martensitic transition. The response of the low-temperature phase assemblage to heating is complex, involving a series of successive interconversions between the coexisting phases. Notably, a broad interconversion plateau is present near 260 K, signifying reentrant kinetic arrest tetragonal phase upon heating because of the combined effects of increased steric hindrance for molecular rotation and melting of charge and orbital order. The geometrically frustrated pyrochlore lattice adopted by the paramagnetic S = 1/2 O-2(-) units provides an intimate link between the crystal and magnetic properties of charge-ordered Cs4O6, naturally accounting for the absence of magnetic order.

Název v anglickém jazyce

Elusive Valence Transition in Mixed-Valence Sesquioxide Cs4O6

Popis výsledku anglicky

Cs4O6 is a mixed-valence molecular oxide with a cubic structure, comprising valency-delocalized O-2(4/3-) units and with properties highly sensitive to cooling protocols. Here we use neutron powder diffraction to authenticate that, while upon deep quenching the cubic phase is kinetically arrested down to cryogenic temperatures, ultraslow cooling results in an incomplete structural transition to a contracted tetragonal phase. Two dioxygen anions in a 1:2 ratio are identified, providing evidence that the transition is accompanied by charge and orbital order and stabilizes a Robin-Day Class II mixed-valence state, comprising O-2(2-) and O-2(-) anions. The phenomenology of the phase change is consistent with that of a martensitic transition. The response of the low-temperature phase assemblage to heating is complex, involving a series of successive interconversions between the coexisting phases. Notably, a broad interconversion plateau is present near 260 K, signifying reentrant kinetic arrest tetragonal phase upon heating because of the combined effects of increased steric hindrance for molecular rotation and melting of charge and orbital order. The geometrically frustrated pyrochlore lattice adopted by the paramagnetic S = 1/2 O-2(-) units provides an intimate link between the crystal and magnetic properties of charge-ordered Cs4O6, naturally accounting for the absence of magnetic order.

Druh

J_imp - Článek v periodiku v databázi Web of Science

CEP obor

—

OECD FORD obor

10302 - Condensed matter physics (including formerly solid state physics, supercond.)

Projekt

<a href="/cs/project/EF15_003%2F0000487" target="_blank" >EF15_003/0000487: Fyzika martensitické transformace pro rozšíření funkcionality krystalických materiálů a nanostruktur</a><br>

Návaznosti

P - Projekt vyzkumu a vyvoje financovany z verejnych zdroju (s odkazem do CEP)<br>I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Rok uplatnění

2019

Kód důvěrnosti údajů

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

Název periodika

Inorganic Chemistry

ISSN

0020-1669

e-ISSN

—

Svazek periodika

58

Číslo periodika v rámci svazku

21

Stát vydavatele periodika

US - Spojené státy americké

Počet stran výsledku

10

Strana od-do

14532-14541

Kód UT WoS článku

000494894400027

EID výsledku v databázi Scopus

2-s2.0-85073813928