Abstract
Crystals of the new solid compounds Tm(Al1-xMnx)B4 (x = 0.002 ~ 0.100) and R(Al0.995Mn0.005)B4 (R = rare earth), were grown from R2O3 and crystalline B powders for Al and Mn mixed flux. Mixture of the starting materials was heated up to1773 K in an Ar atmosphere and kept at that temperature for 5 h, then the molten flux solution was slowly cooled down at a rate of 50 K/h. Tm(Al1-xMnx)B4 compounds were obtained as a single phase from the Al1-xMnx flux (x = 0.005 ~ 0.100). R(Al0.995Mn0.005)B4 compounds were obtained as in the case of R(Ho, Er, Tm, Yb, Lu). ThB4-type compounds were formed in the case of R (Gd, Tb, Dy, Ho). The lattice constants of Ho(Al, Mn)B4 and Lu(Al, Mn)B4 obtained were in the range of a = 3.475(1), b = 5.932(1), c = 11.465(1) Å and a = 3.434(1), b = 5.895(1), c = 11.391(1) Å. The lattice constants were smaller than those of RAlB4 by dissolving Mn atom into Al atom. The values of the hardness for R(Al, Mn)B4 were in the range of 11.9 ~ 13.7 GPa. The magnetic susceptibilities of both Er(Al0.995Mn0.005)B4 and Yb(Al0.995Mn0.005)B4 show antiferromagnetic transitions at 3.5 K and 12 K, respectively.
