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First Principle Surface Analysis of YF3 and Isostructural HoF3

Anders, Jennifer and Limberg, Niklas and Paulus, Beate – 2022

The trifluorides of the two high field strength elements yttrium and holmium are studied by periodic density functional theory. As a lanthanide, holmium also belongs to the group of rare earth elements (REE). Due to their equivalent geochemical behavior, both elements form a geochemical twin pair and consequently, yttrium is generally associated with the REE as REE+Y. Interestingly, it has been found that DFT/DFT+U describe bulk HoF3 best, when the 4f-electrons are excluded from the valence region. An extensive surface stability analysis of YF3 (PBE) and HoF3 (PBE+Ud/3 eV/4f-in-core) using two-dimensional surface models (slabs) is performed. All seven low-lying Miller indices surfaces are considered with all possible stoichiometric or substoichiometric terminations with a maximal fluorine-deficit of two. This leads to a scope of 24 terminations per compound. The resulting Wulff plots consists of seven surfaces with 5–26% abundance for YF3 and six surfaces with 6–34% for HoF3. The stoichiometric (010) surface is dominating in both compounds. However, subtle differences have been found between these two geochemical twins.

Title
First Principle Surface Analysis of YF3 and Isostructural HoF3
Author
Anders, Jennifer and Limberg, Niklas and Paulus, Beate
Date
2022
Identifier
DOI: 10.3390/ma15176048
Source(s)
Citation
Materials 2022, 6048.