Wibowo Arief C, Malliakas Christos D, Chung Duck Young, Im Jino, Freeman Arthur J, Kanatzidis Mercouri G
Materials Science Division, Argonne National Laboratory , Argonne, Illinois 60439, United States.
Inorg Chem. 2013 Oct 21;52(20):11875-80. doi: 10.1021/ic4014174. Epub 2013 Oct 9.
The new compounds TlHg6Q4Br5 (Q = S, Se) are reported along with their syntheses, crystal structures, and thermal and optical properties, as well as electronic band structure calculations. Both compounds crystallize in the tetragonal I4/m space group with a = 14.145(1) Å, c = 8.803(1) Å, and dcalc = 7.299 g/cm(3) for TlHg6S4Br5 (compound 1) and a = 14.518(2) Å, c = 8.782(1) Å, and dcalc = 7.619 g/cm(3) for TlHg6Se4Br5 (compound 2). They consist of cuboid Hg12Q8 building units interconnected by trigonal pyramids of BrHg3, forming a three-dimensional structure. The interstitial spaces are filled with thallium and bromide ions. Compounds 1 and 2 melt incongruently and show band gaps of 3.03 and 2.80 eV, respectively, which agree well with the calculated ones. First-principles electronic structure calculations at the density functional theory level reveal that both compounds have indirect band gaps, but there also exist direct transitions at energies similar to the indirect gaps.
报道了新化合物TlHg6Q4Br5（Q = S，Se）及其合成方法、晶体结构、热学和光学性质，以及电子能带结构计算。两种化合物均结晶于四方晶系I4/m空间群，对于TlHg6S4Br5（化合物1），a = 14.145(1) Å，c = 8.803(1) Å，dcalc = 7.299 g/cm³；对于TlHg6Se4Br5（化合物2），a = 14.518(2) Å，c = 8.782(1) Å，dcalc = 7.619 g/cm³。它们由长方体Hg12Q8结构单元通过BrHg3三角锥相互连接而成，形成三维结构。间隙空间填充有铊离子和溴离子。化合物1和2发生不一致熔融，带隙分别为3.03和2.80 eV，与计算值吻合良好。密度泛函理论水平的第一性原理电子结构计算表明，两种化合物均具有间接带隙，但在与间接带隙相似的能量处也存在直接跃迁。
