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High-pressure crystal structure and phase transitions in B2O3
Dominik Spahr1, Sean S Sebastian2, Lukas Brüning2
1Goethe University Frankfurt, Institute of Geosciences, Altenhöferallee 1, Frankfurt 60438, Germany. d.spahr@kristall.uni-frankfurt.de.
Chemical Communications (Cambridge, England)
|March 13, 2026
Summary
A new high-pressure boron oxide (B2O3) polymorph, B2O3-P212121, was synthesized and characterized. This non-centrosymmetric crystal structure, featuring corner-sharing tetrahedra, can be recovered at ambient conditions.
Area of Science:
- Materials Science
- Solid State Chemistry
- High-Pressure Physics
Background:
- Boron trioxide (B2O3) exhibits complex phase behavior under high pressure.
- Understanding the structural evolution of B2O3 is crucial for materials science applications.
Purpose of the Study:
- To synthesize and characterize a novel high-pressure polymorph of boron oxide.
- To determine the crystal structure and properties of this new phase.
Main Methods:
- High-pressure synthesis using a laser-heated diamond anvil cell.
- Crystal structure determination via synchrotron single crystal X-ray diffraction.
- Computational analysis using density functional theory (DFT) and experimental Raman spectroscopy for confirmation.
Main Results:
- A new high-pressure polymorph, B2O3-P212121, was successfully synthesized at 50 GPa and temperatures up to 2500 K.
- The crystal structure was identified as non-centrosymmetric with space group P212121, characterized by corner-sharing [BO4] tetrahedra.
- Experimental and DFT data confirmed the structure, which aligns with previous theoretical predictions.
- The B2O3-P212121 polymorph is recoverable under ambient conditions.
Conclusions:
- The discovery of B2O3-P212121 expands the known phase diagram of boron oxide.
- The non-centrosymmetric nature of this polymorph may have implications for nonlinear optical properties.
- The recoverability of this high-pressure phase opens avenues for further investigation at ambient conditions.
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