Abstract
Abstract
AlLB14 (L=Li or Na or K) crystals were grown using LiF or NaF or KF and crystalline boron powders as the starting materials using a high-temperature Al melt at soaking temperature 1573 ∼ 1773 K for a soaking time of 5 h under an Ar atmosphere. AlLiB14 and AlNaB14 crystals were obtained from LiF or NaF and B powders, and the atomic ratios (n=B/L = 2.0 ∼ 4.0) of starting materials. The AlKB14 crystal was not obtained from KF and B powders as starting materials. The micro-Vickers hardness of AlLB14 crystals is 24(±1) GPa for AlLiB14 and 25(±1) GPa for AlNaB14. The oxidation initiation temperature of AlLiB14 was about 815 K, and the peak due to the exothermic reaction was about 960 K for AlLiB14 and about 990 K for AlNaB14. The final oxidation products were Li2B2O4, Al4B2O9, B2O3, and amorphous phases. The values for the electrical resistivity of the AlLB14 compound were 2.4 ∼ 157 Ω·cm.