Charge Order and Negative Thermal Expansion in V 2 OPO 4

The semivalent oxyphosphate V OPO is found to have long-range V /V charge ordering up to 605 K where a monoclinic to tetragonal structural transition and a switch from positive to negative thermal expansion are observed. V-V bonding within orbital polymer chains is proposed as the key factor in the...

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Veröffentlicht in:Journal of the American Chemical Society 2018-01, Vol.140 (2), p.636-641
Hauptverfasser: Pachoud, Elise, Cumby, James, Lithgow, Calum T, Attfield, J Paul
Format: Artikel
Sprache:eng
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Zusammenfassung:The semivalent oxyphosphate V OPO is found to have long-range V /V charge ordering up to 605 K where a monoclinic to tetragonal structural transition and a switch from positive to negative thermal expansion are observed. V-V bonding within orbital polymer chains is proposed as the key factor in the novel switch of thermal expansion behavior, as loss of V-V bonding enables transverse oxygen motions to dominate the thermal expansion at high temperatures. Ferrimagnetic order of V spin up and V spin down states is observed below a magnetic ordering transition at 164 K, and susceptibility measurements evidence local spin pairing correlations to higher temperatures.
ISSN:0002-7863
1520-5126
DOI:10.1021/jacs.7b09441