Transition-Metal-Rich Borides - Fascinating Crystal Structures and Magnetic Properties

The ability to design and predict new phases in solid-state chemistry remains a challenge. However, experiment and theory have been working together in the last decade to find new phases with targeted magnetic properties in the family of transition-metal-rich borides. These studies were very successful for boride phases crystallizing with the Ti3Co5B2 structure type. Furthermore, strong variations of the magnetic properties in some series of compounds as a function of the number of valence electrons were observed experimentally and explained by using density functional theory calculations. The Zn11Rh18B8 and Th7Fe3 structure types have also produced many magnetically ordered phases, whereas the new Ti1.6Os1.4RuB2 and Ti1+xRh2-x+yIr3-yB2 structure types have the potential to produce new materials with interesting magnetic properties. The large family of perovskite boride phases has welcomed new members whose structures enable the ordering of boron atoms and vacancies. Renewed interest has been observed for boride phases crystallizing with the Cr23C6-type structure, whose magnetic properties were mainly studied before the nineties.