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First-order phase transition in the Li2B12H12 system.
Mark Paskevicius1, Mark P Pitt, David H Brown
1Department of Imaging and Applied Physics, Fuels and Energy Technology Institute, Curtin University, GPO Box U1987, Perth 6845, WA, Australia. mark.paskevicius@gmail.com.
Physical Chemistry Chemical Physics : PCCP
|September 3, 2013
Summary
High-temperature X-ray diffraction reveals a phase transition in lithium dodecahydrotriborate (Li2B12H12) at 355°C. This transition involves unit cell expansion and decomposition, suggesting potential for lithium ion conduction.
Area of Science:
- Solid-state chemistry
- Materials science
- Crystallography
Background:
- Lithium dodecahydrotriborate (Li2B12H12) is a promising material for solid-state electrolytes.
- Understanding its thermal stability and phase behavior is crucial for developing advanced battery technologies.
Purpose of the Study:
- To investigate the in situ thermal decomposition of anhydrous Li2B12H12.
- To characterize the phase transitions and structural changes occurring during heating.
Main Methods:
- In situ high-resolution synchrotron X-ray diffraction was employed.
- The study focused on monitoring structural changes as a function of temperature.
Main Results:
- A first-order phase transition was observed at 355°C.
- The transition involved an 8.7% expansion in unit cell volume, forming a β-Li2B12H12 polymorph.
- This polymorph subsequently decomposed into a hydrogen-poor γ-Li2B12H12-x phase.
Conclusions:
- The observed unit cell expansion is attributed to reorientational motion of the B12H12(2-) anions.
- The data indicates a frustrated Li(+) lattice, suggesting potential for lithium ion conduction.
- These findings provide insights into the thermal behavior and ionic conductivity mechanisms of Li2B12H12.
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