The study of re dodecaborides zone melting process Available to Purchase

It was investigated the melting nature of LnB₁₂ (Ln: Tb÷Tm, Lu) at various gaseous medium pressures (∼10⁻²Pa, 0.2÷2.2 MPa). Results of X‐ray, metallography, and chemical analysis show that for studied dodecarborides it is typical the incongruent evaporation with preferential loss of boron, that may result in formation of additional phase with less boron content, than in dodecaborides. The use of the inert gas increased pressure permitted to prevent the boron evaporation and made possible to obtain the zone‐melting single phase dodecaborides of Dy, Ho, Er, Tm, Lu. Consequently, the melting process of these compounds has congruent nature. The zone melting single‐phase dodecaboride of terbium does not work to obtain even at gaseous medium pressures to 2.2 MPa and crystallization rates to 7.5 mm/min. Always it was resulted the mixture of terbium hexa‐ and dodecaboride. The choose of corresponding crystallization rates allowed to prepare the single crystals of Er, Tm, Lu dodecaborides. The erbium and lutetium dodecaborides single crystals grow spontaneously in [110] direction, the thulium dodecaboride‐ in [102]. The zone melting dysprosium and holmium dodecaborides samples were obtained only in the form of polycrystal rods. The use of high purity source materials, refinement from having impurities by zone‐melting and growth from seeds made possible to obtain the high‐purity polycrystals and single crystals. So it was prepared LuB₁₂ single crystal with ratio ρ₃₀₀/ρ_4.2= 165, that is the biggest known value for diagmagnitic RE borides.