First non-icosahedral boron allotrope synthesized at high pressure and high temperature

TL;DR

This paper reports the synthesis and structural analysis of the first non-icosahedral boron allotrope, { extzeta}-B, created under extreme high-pressure and high-temperature conditions, confirming theoretical predictions.

Contribution

It presents the first experimental synthesis and structural determination of a non-icosahedral boron allotrope, advancing understanding of boron's phase behavior under extreme conditions.

Findings

Successful synthesis of { extzeta}-B at 115 GPa and 2100 K.

Structural determination using single-crystal synchrotron X-ray diffraction.

Insights into boron's phase transformations under high pressure.

Abstract

Theoretical predictions of pressure-induced phase transformations often become long-standing enigmas because of limitations of contemporary available experimental possibilities. Hitherto the existence of a non-icosahedral boron allotrope has been one of them. Here we report on the first non-icosahedral boron allotrope, which we denoted as {\zeta}-B, with the orthorhombic {\alpha}-Ga-type structure (space group Cmce) synthesized in a diamond anvil cell at extreme high-pressure high-temperature conditions (115 GPa and 2100 K). The structure of {\zeta}-B was solved using single-crystal synchrotron X-ray diffraction and its compressional behavior was studied in the range of very high pressures (115 GPa to 135 GPa). Experimental validation of theoretical predictions reveals the degree of our up-to-date comprehension of condensed matter and promotes further development of the solid state physics and chemistry.