Superconductivity of Ca(Al0.5,Si0.5)2, a ternary silicide with the AlB2-type structure

Abstract

A ternary silicide Ca(Al0.5,Si0.5)2 was prepared by Ar arc melting. Powder x-ray diffraction measurement indicates that it has the AlB2-type structure with lattice constants of a=4.1905(5) and c=4.3992(8) Å, where Si and Al atoms are arranged in the disordered honeycomb lattice and Ca atoms are intercalated between them. The silicide is isostructural with a superconductor MgB2. Electrical resistivity and dc magnetization measurements revealed that it is a superconductor with a TC of 7.7 K.

Superconductivity in the Honeycomb-Lattice Pnictide SrPtAs

“…MgB 2 (T c ¼ 39 K) 7) with an AlB 2 -type structure, CaAlSi (T c ¼ 5:68{7:7 K) 8,9) with an AlB 2 derivative structure, and CaC 6 (T c ¼ 11:5 K) 10,11) with an intercalated-graphite structure exhibit superconductivity with a relatively high T c owing to a strong electron-phonon coupling, 9,12,13) soft phonons, 14,15) multibands/multigaps, 16) and interlayer bands. 17) In this paper, we report superconductivity in SrPtAs with T c ¼ 2:4 K. To our knowledge, this is the first superconducting pnictide with a honeycomb lattice structure.…”

Electrons and phonons in the ternary alloyCaAl2−xSixas a function of composition

“…187) symmetry, 2 obviously lower than the C 32 symmetry described above, and apparently favourable with respect to other possible ordering patterns. An analysis of powder x-ray diffraction patterns performed by Imai et al 28 suggests, instead, the disordered phase. The question is still under debate and no conclusive experimental measure has been reported yet.…”

Superconductivity of MI(MII0.5,Si0.5)2 (MI=Sr and Ba, MII=Al and Ga), ternary silicides with the AlB2-type structure

“…Furthermore, a ternary silicide, Ca(Al 0.5 , Si 0.5 ) 2 , which has the AlB 2 -type structure, has been reported to be a superconductor with a T C of 7.7 K [12]. Ternary silicides Sr(Al x , Si 1-x ) 2 and Ba(Al x , Si 1-x ) 2 have been reported to have the AlB 2 -type structure [13][14][15][16], though their electrical properties have not been examined yet.…”