Abstract
We present a combined single-crystal x-ray diffuse scattering and ab initio molecular dynamics study of lead telluride, PbTe. Well-known for its thermoelectric and narrow-gap semiconducting properties, PbTe recently achieved further notoriety following the report of an unusual off-centering of the lead atoms, accompanied by a local symmetry breaking, on heating. This observation, which was named emphanisis, ignited considerable controversy regarding the details of the underlying local structure and the appropriate interpretation of the total scattering experiments. In this study, we identify an unusual correlated local dipole formation extending over several unit cells with an associated local reduction of the cubic symmetry in both our x-ray diffuse scattering measurements and our molecular dynamics simulations. Importantly, when averaged spatially or temporally, the most probable positions for the ions are at the centers of their coordination polyhedra. Our results therefore clarify the nature of the local symmetry breaking, and reveal the source of the earlier controversy regarding the existence or absence of off-centering. Finally, we provide an interpretation of the behavior in terms of coupled soft optical and acoustic modes which is linked also to the high thermoelectric performance of PbTe.
| Original language | English |
|---|---|
| Article number | 085402 |
| Journal | Physical Review Materials |
| Volume | 2 |
| Issue number | 8 |
| DOIs | |
| Publication status | Published - Aug 6 2018 |
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ASJC Scopus subject areas
- Materials Science(all)
- Physics and Astronomy (miscellaneous)
Cite this
Correlated local dipoles in PbTe. / Sangiorgio, Boris; Bozin, Emil S.; Malliakas, Christos D.; Fechner, Michael; Simonov, Arkadiy; Kanatzidis, Mercouri G; Billinge, Simon J.L.; Spaldin, Nicola A.; Weber, Thomas.
In: Physical Review Materials, Vol. 2, No. 8, 085402, 06.08.2018.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Correlated local dipoles in PbTe
AU - Sangiorgio, Boris
AU - Bozin, Emil S.
AU - Malliakas, Christos D.
AU - Fechner, Michael
AU - Simonov, Arkadiy
AU - Kanatzidis, Mercouri G
AU - Billinge, Simon J.L.
AU - Spaldin, Nicola A.
AU - Weber, Thomas
PY - 2018/8/6
Y1 - 2018/8/6
N2 - We present a combined single-crystal x-ray diffuse scattering and ab initio molecular dynamics study of lead telluride, PbTe. Well-known for its thermoelectric and narrow-gap semiconducting properties, PbTe recently achieved further notoriety following the report of an unusual off-centering of the lead atoms, accompanied by a local symmetry breaking, on heating. This observation, which was named emphanisis, ignited considerable controversy regarding the details of the underlying local structure and the appropriate interpretation of the total scattering experiments. In this study, we identify an unusual correlated local dipole formation extending over several unit cells with an associated local reduction of the cubic symmetry in both our x-ray diffuse scattering measurements and our molecular dynamics simulations. Importantly, when averaged spatially or temporally, the most probable positions for the ions are at the centers of their coordination polyhedra. Our results therefore clarify the nature of the local symmetry breaking, and reveal the source of the earlier controversy regarding the existence or absence of off-centering. Finally, we provide an interpretation of the behavior in terms of coupled soft optical and acoustic modes which is linked also to the high thermoelectric performance of PbTe.
AB - We present a combined single-crystal x-ray diffuse scattering and ab initio molecular dynamics study of lead telluride, PbTe. Well-known for its thermoelectric and narrow-gap semiconducting properties, PbTe recently achieved further notoriety following the report of an unusual off-centering of the lead atoms, accompanied by a local symmetry breaking, on heating. This observation, which was named emphanisis, ignited considerable controversy regarding the details of the underlying local structure and the appropriate interpretation of the total scattering experiments. In this study, we identify an unusual correlated local dipole formation extending over several unit cells with an associated local reduction of the cubic symmetry in both our x-ray diffuse scattering measurements and our molecular dynamics simulations. Importantly, when averaged spatially or temporally, the most probable positions for the ions are at the centers of their coordination polyhedra. Our results therefore clarify the nature of the local symmetry breaking, and reveal the source of the earlier controversy regarding the existence or absence of off-centering. Finally, we provide an interpretation of the behavior in terms of coupled soft optical and acoustic modes which is linked also to the high thermoelectric performance of PbTe.
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U2 - 10.1103/PhysRevMaterials.2.085402
DO - 10.1103/PhysRevMaterials.2.085402
M3 - Article
VL - 2
JO - Physical Review Materials
JF - Physical Review Materials
SN - 2475-9953
IS - 8
M1 - 085402
ER -