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Effect of molecular intercalation on the local structure of superconducting Nax(NH3)yMoSe2 system.

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Title: Effect of molecular intercalation on the local structure of superconducting Nax(NH3)yMoSe2 system.
Authors: Simonelli, L.1, Paris, E.2, Wakita, T.3, Marini, C.1, Terashima, K.3, Miao, X.3, Olszewski, W.1,4, Ramanan, N.1, Heinis, D.1, Kubozono, Y.3, Yokoya, T.3, Saini, N.L.2 Naurang.saini@roma1.infn.it
Source: Journal of Physics & Chemistry of Solids. Dec2017, Vol. 111, p70-74. 5p.
Subjects: Desorption, X-ray absorption, Molecules, Ions, Superconductivity
Abstract: We have studied the local structure of layered Na x (NH 3 ) y MoSe 2 system by Mo K-edge extended X-ray absorption fine structure (EXAFS) measurements performed as a function of temperature. We find that molecular intercalation in MoSe 2 largely affects the Mo-Se network while Mo-Mo seems to sustain small changes. The Einstein temperature ( Θ E ) of Mo-Mo distance hardly changes ( ∼ 264 K) indicating that bond strength of this distance remains unaffected by intercalation. On the other hand, Mo-Se distance suffers a softening, revealed by the decrease of Θ E from ∼ 364 K to ∼ 350 K. The results indicate that Na + ion transported by NH 3 molecules may enter between the two MoSe-layers resulting reduced Se-Se coupling. Therefore, increased hybridization between Se 4p and Mo 4d orbitals due to inter-layer disorder is the likely reason of metallicity in intercalated MoSe 2 and superconductivity at low temperature. [ABSTRACT FROM AUTHOR]
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Database: Engineering Source
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Abstract:We have studied the local structure of layered Na x (NH 3 ) y MoSe 2 system by Mo K-edge extended X-ray absorption fine structure (EXAFS) measurements performed as a function of temperature. We find that molecular intercalation in MoSe 2 largely affects the Mo-Se network while Mo-Mo seems to sustain small changes. The Einstein temperature ( Θ E ) of Mo-Mo distance hardly changes ( ∼ 264 K) indicating that bond strength of this distance remains unaffected by intercalation. On the other hand, Mo-Se distance suffers a softening, revealed by the decrease of Θ E from ∼ 364 K to ∼ 350 K. The results indicate that Na + ion transported by NH 3 molecules may enter between the two MoSe-layers resulting reduced Se-Se coupling. Therefore, increased hybridization between Se 4p and Mo 4d orbitals due to inter-layer disorder is the likely reason of metallicity in intercalated MoSe 2 and superconductivity at low temperature. [ABSTRACT FROM AUTHOR]
ISSN:00223697
DOI:10.1016/j.jpcs.2017.07.011