Yttrium borides

Yttrium boride refers to a crystalline material composed of different proportions of yttrium and boron, such as YB₂, YB₄, YB₆, YB₁₂, YB₂₅, YB₅₀ and YB₆₆. They are all gray-colored, hard solids having high melting temperatures. The most common form is the yttrium hexaboride YB₆. It exhibits superconductivity at relatively high temperature of 8.4 K and, similar to LaB₆, is an electron cathode. Another remarkable yttrium boride is YB₆₆. It has a large lattice constant (2.344 nm), high thermal and mechanical stability, and therefore is used as a diffraction grating for low-energy synchrotron radiation (1–2 keV).