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Imine Metathesis by Silica-Supported Catalysts Using the Methodology of Surface Organometallic Chemistry
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Triangulating Dopant-Level Mn(II) Insertion in a Cs2NaBiCl6 Double Perovskite Using Magnetic Resonance Spectroscopy
Abhoy Karmakar1, Guy M Bernard1, Arkadii Pominov1
1Department of Chemistry, University of Alberta, Edmonton, Alberta T6G 2G2, Canada.
Journal of the American Chemical Society
|February 14, 2023
Summary
This study uses magnetic resonance to investigate manganese-doped lead-free double perovskites. Manganese doping occurs at bismuth sites, influencing the material
Area of Science:
- Materials Science
- Solid-State Chemistry
- Spectroscopy
Background:
- Lead-free metal halide double perovskites are promising for optoelectronics.
- Doping with transition metals tunes optical bandgaps.
- The incorporation site of Mn(II) in Cs2NaBiCl6 is poorly understood at low doping levels.
Purpose of the Study:
- To determine the atomic-level structure of Mn(II) incorporation in Cs2NaBiCl6.
- To understand structure-property relationships for advanced optoelectronic applications.
- To elucidate the site of Mn(II) insertion using magnetic resonance techniques.
Main Methods:
- A multi-technique approach combining solid-state nuclear magnetic resonance (NMR), dynamic nuclear polarization (DNP), and electron paramagnetic resonance (EPR) spectroscopies.
- Multinuclear NMR (23Na, 35Cl, 133Cs, 209Bi) to probe local environments.
- EPR and HYperfine Sublevel CORrelation (HYSCORE) spectroscopy to identify Mn(II) oxidation state, symmetry, and interactions.
Main Results:
- Low levels of Mn(II) incorporation were detected, with affected spins showing paramagnetic relaxation enhancement (PRE).
- EPR confirmed Mn(II) in octahedral symmetry, with no 209Bi correlations in HYSCORE suggesting substitution at Bi sites.
- NMR and EPR indicated a cubic structure at room temperature, with deviations below 30 K. DNP NMR supported homogeneous Mn(II) distribution.
Conclusions:
- Mn(II) substitutes for Bi in the Cs2NaBiCl6 double perovskite structure.
- The material maintains cubic symmetry at room temperature but shows deviations at low temperatures.
- Magnetic resonance techniques successfully elucidated the Mn(II) incorporation site and distribution, advancing understanding for optoelectronic applications.
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