The pressure-dependent behaviour of NaMn7O12(up to 40 GPa) is studied and discussed by means of single-crystal X-ray diffraction and resistance measurements carried out on powdered samples. A transition from thermally activated transport mechanism to semimetal takes place above 18 GPa, accompanied by a change in the compressibility of the system. On the other hand, the crystallographic determinations rule out a symmetry change to be at the origin of the transition, despite all the structural parameters pointing to a symmetrizing effect of pressure. Bond valence sum calculations indicate a charge transfer from the octahedrally coordinated manganese ions to the square planar ones, likely favouring the delocalization of the carriers.

High pressure induced insulator-to-semimetal transition through intersite charge in NaMn7O12 / Delmonte, Davide; Mezzadri, Francesco; Orlandi, Fabio; Calestani, Gianluca; Amiel, Yehezkel; Gilioli, Edmondo. - In: CRYSTALS. - ISSN 2073-4352. - 8:2(2018), p. 81. [10.3390/cryst8020081]

High pressure induced insulator-to-semimetal transition through intersite charge in NaMn7O12

Delmonte, Davide
;
Mezzadri, Francesco;Orlandi, Fabio;Calestani, Gianluca;
2018

Abstract

The pressure-dependent behaviour of NaMn7O12(up to 40 GPa) is studied and discussed by means of single-crystal X-ray diffraction and resistance measurements carried out on powdered samples. A transition from thermally activated transport mechanism to semimetal takes place above 18 GPa, accompanied by a change in the compressibility of the system. On the other hand, the crystallographic determinations rule out a symmetry change to be at the origin of the transition, despite all the structural parameters pointing to a symmetrizing effect of pressure. Bond valence sum calculations indicate a charge transfer from the octahedrally coordinated manganese ions to the square planar ones, likely favouring the delocalization of the carriers.
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11381/2839352
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