English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Zendy Plus

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Zendy Tools

Zendy Open

{\gamma}-B28 is a recently established high-pressure phase of boron. Itsstructure consists of icosahedral B12 clusters and B2 dumbbells in a NaCl-typearrangement (B2){\delta}+(B12){\delta}- and displays a significant chargetransfer {\delta}~0.5- 0.6. The discovery of this phase proved essential forthe understanding and construction of the phase diagram of boron. {\gamma}-B28was first experimentally obtained as a pure boron allotrope in early 2004 andits structure was discovered in 2006. This paper reviews recent results and inparticular deals with the contentious issues related to the equation of state,hardness, putative isostructural phase transformation at ~40 GPa, and debateson the nature of chemical bonding in this phase. Our analysis confirms that (a)calculations based on density functional theory give an accurate description ofits equation of state, (b) the reported isostructural phase transformation in{\gamma}-B28 is an artifact rather than a fact, (c) the best estimate ofhardness of this phase is 50 GPa, (d) chemical bonding in this phase has asignificant degree of ionicity. Apart from presenting an overview of previousresults within a consistent view grounded in experiment, thermodynamics andquantum mechanics, we present new results on Bader charges in {\gamma}-B28using different levels of quantum-mechanical theory (GGA, exact exchange, andHSE06 hybrid functional), and show that the earlier conclusion aboutsignificant degree of partial ionicity in this phase is very robust.

The high-pressure phase of boron, {\gamma}-B28: disputes and conclusions of 5 years after discovery