The diversity of the crystal structures of rare-earth borides results in unusual physical properties and potential applications in thermopower generation. Thermal conductivity of boron icosahedra based compounds is low because of their complex crystal structure; this property is favored for thermoelectric materials. On the other hand, these compounds exhibit very low (variable range hopping type) p-type electrical conductivity. Increasing the conductivity is a key issue for thermoelectric applications of these borides.
YB is used as a soft-X-ray monochromator for dispersing 1–2 keV synchrotron radiation at some synchrotron radiation facilities. Contrary to thermoelectric applications, high thermal conductivity is desirable for synchrotron radiation monochromators. YB exhibits low, amorphous-like thermal conductivity. However, transition metal doping increases the thermal conductivity twice in YNbB as compared to undoped YB.