Phase transition in the Zr1-xScxB12 system.

A metal-metal transition followed by a structural transition near room temperature was found in the solid solutions between cubic ZrB 12 and tetragonal ScB 12 , i.e., in Zr 1-x Sc x B 12 with compositions in the range of 0.1≤x≤0.9. The high-temperature phase had a face-centered-cubic (fcc) structure with a lattice parameter of a 0 ∼7.4 A and n-type carriers. The low-temperature phase had a period twice longer than for the fcc lattice in the direction of [111], the trigonal space group of R3m and p-type carriers. This phase transition was of first order and was thought to be caused by the Jahn-Teller effect based on the deformation of B 12 clusters followed by the displacement of metallic atoms