Bi12Rh3Ag6I9: Mobile Silver Ions and Surface-Dominated Transport in a Layered Weak Topological Insulator.
10 affiliations
- 1Faculty of Chemistry and Food Chemistry, Dresden University of Technology, 01062Dresden, Germany.
- 2Würzburg-Dresden Cluster of Excellence ctd.qmat, Dresden University of Technology, 01062Dresden, Germany.
- 3Faculty of Physics and Astronomy, University of Würzburg, 97074Würzburg, Germany.
- 4Leibniz Institute for Solid State and Materials Research, 01069Dresden, Germany.
- 5Department of Electrical and Photonics Engineering, Technical University of Denmark, 2800Kgs. Lyngby, Denmark.
- 6Center for Silicon Photonics for Optical Communications (SP.O.C), Technical University of Denmark, 2800Kgs. Lyngby, Denmark.
- 7Department of Physics and Astronomy, University of Bologna, 40127Bologna, Italy.
- 8Center for Computational Quantum Physics, Flatiron Institute, New York, New York10010, United States.
- 9Institute of Applied Physics, Dresden University of Technology, 01062Dresden, Germany.
- 10Institute of Materials Science, Dresden University of Technology, 01062Dresden, Germany.
Abstract
Bi12Rh3Ag6I9 extends the Bi14Rh3I9 family of layered bismuth-rich iodides in which intermetallic topological-insulator sheets alternate with salt-like spacer layers. High-temperature synthesis yields phase-pure powders and millimeter-sized platelets. Single-crystal X-ray diffraction reveals a rhombohedral structure composed of [Bi12Rh3I]2+ layers and [Ag6I8]2- spacers. In this spacer, Ag+ cations occupy 75% of the tetrahedral voids of a double iodide layer, giving rise to intrinsic two-dimensional cation disorder and mobility. Electrochemical impedance spectroscopy reveals a room-temperature ionic conductivity of about 10-6 S cm-1. Density-functional theory including spin-orbit coupling predicts band inversion and weak-topological-insulator invariants, while angle-resolved photoemission spectroscopy corroborates the calculated bulk electronic structure, yielding an experimental bulk band gap of 286 meV. Transport measurements show strongly anisotropic, initially n-type conduction. During the initial measurement cycle, applied bias reduces the electron doping through slow electrochemical deintercalation of silver. After conditioning, bulk conduction is strongly reduced; transport below about 130 K becomes nonactivated, the bias-induced drift ceases below about 50 K as Ag+ motion freezes, and a pronounced resistivity drop perpendicular to the layers below 3.2 K is suggestive of a boundary-sensitive low-dimensional transport regime. Bi12Rh3Ag6I9 demonstrates that spacer chemistry provides a chemical lever for carrier-density control in layered topological insulators.
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BibTeX
@article{carrilloaravena2026bi12rh3ag6i9,
title = {{Bi12Rh3Ag6I9: Mobile Silver Ions and Surface-Dominated Transport in a Layered Weak Topological Insulator.}},
author = {Eduardo Carrillo-Aravena and Johannes Heßdörfer and Christian N Saggau and Armando Consiglio and Shailja Sharma and Friedrich Reinert and Giorgio Sangiovanni and Domenico Di Sante and Oleg Janson and Kornelius Nielsch and Nicolás Pérez and Michael Ruck},
journal = {Inorganic chemistry},
year = {2026},
month = oct,
doi = {10.1021/acs.inorgchem.6c02517},
url = {https://europepmc.org/article/MED/42895400},
note = {CC BY},
}
RIS
TY - JOUR
TI - Bi12Rh3Ag6I9: Mobile Silver Ions and Surface-Dominated Transport in a Layered Weak Topological Insulator.
AU - Eduardo Carrillo-Aravena
AU - Johannes Heßdörfer
AU - Christian N Saggau
AU - Armando Consiglio
AU - Shailja Sharma
AU - Friedrich Reinert
AU - Giorgio Sangiovanni
AU - Domenico Di Sante
AU - Oleg Janson
AU - Kornelius Nielsch
AU - Nicolás Pérez
AU - Michael Ruck
PY - 2026
DA - 2026/10/01
JO - Inorganic chemistry
DO - 10.1021/acs.inorgchem.6c02517
UR - https://europepmc.org/article/MED/42895400
AB - Bi12Rh3Ag6I9 extends the Bi14Rh3I9 family of layered bismuth-rich iodides in which intermetallic topological-insulator sheets alternate with salt-like spacer layers. High-temperature synthesis yields phase-pure powders and millimeter-sized platelets. Single-crystal X-ray diffraction reveals a rhombohedral structure composed of [Bi12Rh3I]2+ layers and [Ag6I8]2- spacers. In this spacer, Ag+ cations occupy 75% of the tetrahedral voids of a double iodide layer, giving rise to intrinsic two-dimensional cation disorder and mobility. Electrochemical impedance spectroscopy reveals a room-temperature ionic conductivity of about 10-6 S cm-1. Density-functional theory including spin-orbit coupling predicts band inversion and weak-topological-insulator invariants, while angle-resolved photoemission spectroscopy corroborates the calculated bulk electronic structure, yielding an experimental bulk band gap of 286 meV. Transport measurements show strongly anisotropic, initially n-type conduction. During the initial measurement cycle, applied bias reduces the electron doping through slow electrochemical deintercalation of silver. After conditioning, bulk conduction is strongly reduced; transport below about 130 K becomes nonactivated, the bias-induced drift ceases below about 50 K as Ag+ motion freezes, and a pronounced resistivity drop perpendicular to the layers below 3.2 K is suggestive of a boundary-sensitive low-dimensional transport regime. Bi12Rh3Ag6I9 demonstrates that spacer chemistry provides a chemical lever for carrier-density control in layered topological insulators.
SN - 0020-1669
SN - 1520-510X
ER -