  We report here ab initio density functional theory (DFT) calculations of
structural, elastic, Peierls stress, thermodynamic and optical properties of
RRh3B (R = Y, Zr and Nb) using the plane wave psedudopotential method. The
materials possess better ductile behavior in comparison with a selection of
layered MAX phases but the anisotropy is strong, particularly in NbRh3B. The
Peierls stress, approximately 3-4 times larger than in MAX phases, show that
dislocation movement may follow but with much reduced occurrences compared to
MAX phases. The temperature and pressure dependence of bulk modulus, specific
heats, thermal expansion coefficient, and Debye temperature are calculated for
the first time for two of the three compounds using the quasi-harmonic Debye
model with phononic effects for elevated temperature and pressure. The obtained
results are discussed in comparison to the behavior of other related compounds.
Further the features of optical functions obtained for the first time are
discussed. The study reveals that the reflectivity is high in the IR-UV regions
up to ~ 17.5 eV (YRh3B, ZrRh3B) and 20 eV (NbRh3B), thus showing promise as
good coating materials.
  Keywords: RRh3B; Quasi-harmonic Debye model; Thermodynamic properties;
Optical properties
