Reaction of rare-earth metals with boron and aluminum

We have used x-ray phase analysis to establish the phase equilibria at 600°C for the systems Gd-Al-B, Tb-Al-B, and Ho-Al-B (the boron-rich sites have not yet been studied). We determined the crystalline structure of the new borides HoAlB₄ and ErAlB₄ (space group Pbam, YCrB₄ type, a=59283(7), b=1.1553(1), c=0.35306(5) mm for HoAlB₄ and a=0.59955(9), b=1.1487(2), c=0.35284(8) nm for ErAlB₄). We synthesized the compound Tm_1?xAl_1?yB₁₄ with MgAlB₁₄ type structure (space group Imma, a=0.5826(2), b=1.0380(2), c=0.8176(2) nm) by the method of crystallization from an aluminum melt.