Abstracts Book - IMRC 2018

• SF4-O016
INSIGHTS ON THE PHASE DIAGRAM OF TWO-DIMENSIONAL
BORON OXIDE AND THE PROPERTIES OF ALPHA-TETRAGONAL
BORON
Jens Kunstmann 1
1 Technische Universität Dresden, Faculty of Chemistry and Food Chemistry, Germany.
Since 2016 boron monolayers (borophene) can be grown on metal surfaces. To
learn about borons affinity to oxygen in reduced dimensions we calculate the
compositional phase diagram of two-dimensional (2D) boron oxide using
density functional theory. Apart from pure boron and B2O3, no evidence for
compounds with stable 2D structures could be found in the studied
stoichiometric range. The phase diagram of the 2D boron-oxygen modifications
thus has a surprisingly simple structure. Our results also imply that 2D boron
seems to be surprisingly inhert towards oxidation.
alpha-tetragonal boron was recently added to the list of known boron
allotropes. Upon annealing of hydrogenated alpha-tetragonal boron the
hydrogen release occurs non-continuous, in two steps, where the second one is
associated with a structural change from alpha-tetragonal to deltaorthorhombic
boron and full hydrogen release. Our free energy calculations
based on density functional theory provide insights on the origin of the two-step
transition, analyze the difference between alpha-tetragonal and deltaorthorhombic
boron and indicate its relation to an order-disorder transition.
Keywords: 2D boron oxide, borophene, alpha-tetragonal boron
Presenting authors email: jens.kunstmann@tu-dresden.de