Department of Applied Chemistry, Graduate School of Engineering, Hiroshima University, Higashi-Hiroshima 739-8527, Japan.
Inorg Chem. 2012 Oct 1;51(19):10300-5. doi: 10.1021/ic301296u. Epub 2012 Sep 14.
Ternary compounds Mg(Mg(1-x)Al(x))Si (0.3 < x < 0.8) have been prepared under high pressure and high temperature conditions of 5 GPa at 800-1100 °C. The single crystal study revealed that the compound (x = 0.45) is isomorphous with the anticotunnite, or the TiNiSi structure, and crystallizes with space group Pnma, with lattice parameters a = 6.9242(2), b = 4.1380(1), c = 7.9618(2) Å, and Z = 4. The compound with x > 0.5 shows superconductivity with a transition temperature (T(c)) ~ 6 K. The compound is a peritectic solid solution associated with other phases such as Mg(9)Si(5), Al, and Si, depending on cooling protocols in the preparation. The band structure calculation on the composition MgAlSi suggests that the Al and Mg orbitals mainly contribute to the density of states near the Fermi level, and the substitution of Mg with Al favors the superconductivity.
三元化合物 Mg(Mg(1-x)Al(x))Si（0.3 < x < 0.8）在 5 GPa 的高温高压条件下于 800-1100°C 下合成。单晶研究表明，化合物（x = 0.45）与反钙钛矿或 TiNiSi 结构同构，空间群为 Pnma，晶格参数 a = 6.9242(2)，b = 4.1380(1)，c = 7.9618(2) Å，Z = 4。x > 0.5 的化合物表现出超导性，转变温度（T(c)）约为 6 K。该化合物是与其他相（如 Mg(9)Si(5)、Al 和 Si）有关的包晶固溶体，具体取决于制备过程中的冷却方案。对组成 MgAlSi 的能带结构计算表明，Al 和 Mg 轨道主要对费米能级附近的态密度有贡献，用 Al 取代 Mg 有利于超导性。
