Five new semiconductors Pb_(5)Sb_(12+x)Bi_(6-x)Se_(32)(x=0,1,2,3,and 4)have been synthesized for the first time,which adopt pavonite-type structure and crystallize in monoclinic C2/m space group.The crystal structure ...Five new semiconductors Pb_(5)Sb_(12+x)Bi_(6-x)Se_(32)(x=0,1,2,3,and 4)have been synthesized for the first time,which adopt pavonite-type structure and crystallize in monoclinic C2/m space group.The crystal structure is composed of two different types of polyhedral slabs.Slab-I is a galena-like structure motif that forms with[MSe_(6)](M=Pb,Sb,and Bi)octahedra and slab-Ⅱcontains one octahedral[MSe_(6)]block and paired squared pyramids[MSe_(5)].Pb_(5)Sb_(12+x)Bi_(6-x)Se_(32)exhibits n-type semiconductor behaviors and the remarkable Seebeck coefficient from-64.1μV K^(-1)for x=0 sample to-242μV K^(-1)forx=4 sample at 300 K.Moreover,the Pb_(5)Sb_(12)Bi_(6)Se_(32)has the highest carrier concentration of 1.35×10^(20)cm^(-3)in pavonite-type materials.The complex compositions,mixed occupancies of the cations,and quasi-two-dimensional structure lead to the low lattice thermal conduc-tivity(κ_(lat))less than 0.48 W m^(-1)K^(-1)from 300 to 723 K,at which Pb_(5)Sb_(16)Bi_(2)Se_(32)especially shows the ultralow value of 0.25 W m^(-1)K^(-1).As a result,the thermoelectric figure of merit,ZT~0.34 at 723 K,is obtained for the intrinsic Pb_(5)Sb_(12)Bi_(6)Se_(32).展开更多
基金supported in part by the National Natural Science Foundation of China(52102218)the National Key Research and Development Program of China(2020YFA0710303)+2 种基金the Fujian Science&Technology Innovation Laboratory for Optoelectronic Information of China(2021ZZ127)the Minjiang Scholar Professorship(GXRC-21004)the Natural Science Foundation of Fujian Province(2021J01594).
文摘Five new semiconductors Pb_(5)Sb_(12+x)Bi_(6-x)Se_(32)(x=0,1,2,3,and 4)have been synthesized for the first time,which adopt pavonite-type structure and crystallize in monoclinic C2/m space group.The crystal structure is composed of two different types of polyhedral slabs.Slab-I is a galena-like structure motif that forms with[MSe_(6)](M=Pb,Sb,and Bi)octahedra and slab-Ⅱcontains one octahedral[MSe_(6)]block and paired squared pyramids[MSe_(5)].Pb_(5)Sb_(12+x)Bi_(6-x)Se_(32)exhibits n-type semiconductor behaviors and the remarkable Seebeck coefficient from-64.1μV K^(-1)for x=0 sample to-242μV K^(-1)forx=4 sample at 300 K.Moreover,the Pb_(5)Sb_(12)Bi_(6)Se_(32)has the highest carrier concentration of 1.35×10^(20)cm^(-3)in pavonite-type materials.The complex compositions,mixed occupancies of the cations,and quasi-two-dimensional structure lead to the low lattice thermal conduc-tivity(κ_(lat))less than 0.48 W m^(-1)K^(-1)from 300 to 723 K,at which Pb_(5)Sb_(16)Bi_(2)Se_(32)especially shows the ultralow value of 0.25 W m^(-1)K^(-1).As a result,the thermoelectric figure of merit,ZT~0.34 at 723 K,is obtained for the intrinsic Pb_(5)Sb_(12)Bi_(6)Se_(32).
