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The pressure-stabilized polymorph of indium triiodide
Danrui Ni1, Haozhe Wang2, Xianghan Xu1
1Department of Chemistry, Princeton University, Princeton, NJ 08544, USA. rcava@princeton.edu.
Dalton Transactions (Cambridge, England : 2003)
|December 13, 2023
Summary
High pressure transforms indium(III) triiodide into a layered rhombohedral structure. This new polymorph, distinct from the ambient form, exhibits a different crystal structure and color, impacting its electronic properties.
Area of Science:
- Materials Science
- Solid-State Chemistry
- Crystallography
Background:
- Indium(III) triiodide (InI3) exhibits polymorphism, with distinct crystal structures and properties under varying pressure and temperature conditions.
- Understanding these structural transitions is crucial for predicting and controlling material behavior.
Purpose of the Study:
- To synthesize and characterize a novel high-pressure polymorph of indium(III) triiodide.
- To elucidate the crystal structure and electronic properties of this new phase.
Main Methods:
- High-pressure and high-temperature synthesis.
- Single crystal X-ray diffraction for unit cell determination.
- Powder X-ray diffraction with Rietveld refinement for crystal structure analysis.
- Diffuse reflectance spectroscopy for band gap estimation.
Main Results:
- A layered rhombohedral polymorph of InI3 was successfully synthesized.
- The crystal structure was determined to be R3̄ with specific lattice parameters (a = 7.214 Å, c = 20.47 Å).
- The high-pressure phase exhibits an orange color, contrasting with the light-yellow ambient monoclinic form.
Conclusions:
- High pressure induces a significant structural transformation in InI3, leading to a layered rhombohedral structure.
- The distinct crystal structures of the ambient and high-pressure InI3 phases suggest differences in their electronic band gaps and potential applications.
