High pressuremonoclinicphasesofSb2Te3

S.M. Souza (1) , C.M Poffo (1) , D.M. Trichès (1) , J.C de Lima (2) , T.A Grandi (2) , A. Polian (3) , Michel Gauthier (3)

1 Departamento de Engenharia Mecanica
2 Departamento deFısica, UniversidadeFederaldeSantaCatarina,CampusUniversita'rio Trindade
3 IMPMC - Institut de minéralogie et de physique des milieux condensés

The effectofpressureonnanostructuredrhombohedral a-Sb2Te3 (phase I)wasinvestigatedusingX-ray diffraction(XRD)andRamanspectroscopy(RS)upto19.2and25.5GPa,respectively.XRDpatterns showedtwonewhighpressurephases(namedphasesIIandIII).FromaRietveldrefinementofXRD patternsof a-Sb2Te3, theunitcellvolumeasafunctionofpressurewasobtainedandthevalueswere fitted toaBirch-Murnaghanequationofstate(BM-EOS).Thebestfitwasobtainedforbulkmodulus B0¼36.170.9GPaanditsderivative B0 0 ¼ 6:270:4 (notfixed).Usingtherefinedstructuraldatafor a-Sb2Te3, forpressuresupto9.8GPa,changesintheangleofsuccession[Te-Sb-Te-Sb-Te],inthe interaromicdistancesofSbandTeatomsbelongingtothisangleofsuccessionandintheinteratomic distancesofatomslocatedonthe c axiswereexamined.Thisanalysisrevealedanelectronictopological transition(ETT)alongthe a and c axes atcloseto3.7GPa.FromtheRSspectra,thefullwidthsathalf maximum(FWHM)oftheRamanactivemodesof a-Sb2Te3 were plottedasfunctionsofpressureand showedanETTalongthe a and c axes atcloseto3.2GPa.TheXRDpatternsofphasesIIandIIIwerewell reproducedassuming b-Bi2Te3 and g-Bi2Te3 structuressimilartothosereportedintheliteraturefor a-Bi2Te3.

Mots clés: Nanocrystals; Thermoelectric materials; Mechanical alloying; X-ray diffraction; Raman spectroscopy; High pressure

Domaines: Autre [cond-mat.other]

S.M. Souza, C.M Poffo, D.M. Trichès, J.C de Lima, T.A Grandi, et al.. High pressuremonoclinicphasesofSb2Te3. Physica B: Condensed Matter, 2012, 407, pp.3781-3789. ⟨10.1016/j.physb.2012.05.061⟩. ⟨hal-00739981⟩