Copper selenide: soft phonon modes and superionic phase transition

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dc.contributor.authorDanilkin, SAen_AU
dc.contributor.authorYethiraj, Men_AU
dc.contributor.authorKearley, GJen_AU
dc.date.accessioned2021-10-01T06:27:41Zen_AU
dc.date.available2021-10-01T06:27:41Zen_AU
dc.date.issued2010-02-03en_AU
dc.date.statistics2021-09-03en_AU
dc.description.abstractThis paper reports lattice dynamical measurements of Cu1.8Se superionic conductor having structure of the superionic α-phase at ambient temperature. Cu2δSe is a mixed ionic-electronic conductor with a superionic transition at 414K in stoichiometric compound Cu2Se. At room temperature the superionic α -phase exists in the composition range from δ = 0.15 to 0.25. The important features of the Cu1.8Se compound is the ordering of Cu atoms observed at ambient temperature [1] which is described as “disordered” α- phase in the literature and presence of low-energy transverse acoustic (TA) modes [2]. Measurements of phonon dispersion curves were performed with the new triple-axis spectrometer, TAIPAN, at the OPAL reactor [3]. We found that TA [100], TA [111] and TA1 [110] phonon branches demonstrate a decrease in frequency at wavevectors q/qm > 0.5 rather than the flattening observed previously. Results are compared with calculated density functional theoretical calculations showing the presence of unstable soft mode related to ordering of Cu atoms in Cu1.8Se at room temperature followed by α- β phase transition at a lower temperature. Superstructure arising from the ordering causes effects similar to the folding of the Brillouin zone, although phonon intensities at new Brillouin zone centres are weak. The coupling of low-energy phonon modes with displacement of mobile ions can explain the strong damping of phonons at q/qm > 0.5.en_AU
dc.identifier.citationDanilkin, S. A., Yethiraj, M., Kearley, G. J. (2010). Copper selenide: soft phonon modes and superionic phase transition. Paper presented to the 34th Annual Condensed Matter and Materials Meeting 2010, Waiheke Island Resort, Waiheke, Auckland, New Zealand 2 - 5 February 2010. Retrieved from: https://physics.org.au/wp-content/uploads/cmm/2010/en_AU
dc.identifier.conferenceenddate5 February 2010en_AU
dc.identifier.conferencename4th Annual Condensed Matter and Materials Meeting 2010en_AU
dc.identifier.conferenceplaceAuckland, New Zealanden_AU
dc.identifier.conferencestartdate2 February 2010en_AU
dc.identifier.isbn978-0-646-53897-6en_AU
dc.identifier.urihttps://physics.org.au/wp-content/uploads/cmm/2010/en_AU
dc.identifier.urihttps://apo.ansto.gov.au/dspace/handle/10238/11853en_AU
dc.language.isoenen_AU
dc.publisherAustralian Institute of Physicsen_AU
dc.subjectCopper selenidesen_AU
dc.subjectCopperen_AU
dc.subjectSelenidesen_AU
dc.subjectAmbient temperatureen_AU
dc.subjectCrystal latticesen_AU
dc.subjectCrystal structureen_AU
dc.subjectStoichiometryen_AU
dc.subjectOPAL Reactoren_AU
dc.subjectPhononsen_AU
dc.subjectIonsen_AU
dc.titleCopper selenide: soft phonon modes and superionic phase transitionen_AU
dc.typeConference Abstracten_AU
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