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A new compound NaIn 3 S 5 has been obtained in the CaS–In 2 S 3 /NaBr system via a reactive flux method. NaIn 3 S 5 crystallizes in the orthorhombic space group Pbam (No. 55) with a = 12.4963(8) Å, b = 16.0811(10) Å, c = 3.8041(2) Å, and Z = 4. The NaIn 3 S 5 structure is characterized by a three dimensional framework consisting of interconnected tripartite-octahedral [ In 3 S 8 ] ∞ 1 infinite chains, with Na + cations residing in the one-dimensional channels along the c direction defined by S(1), S(2), S(3) and S(4) atoms. The optical reflectance measurement shows a band gap of 2.18 eV for NaIn 3 S 5 . Electronic structure calculation by the CASTEP code not only indicates that NaIn 3 S 5 is an indirect band gap semiconductor, but also explains why its experimental band gap is close to that of β-In 2 S 3 . [ABSTRACT FROM AUTHOR]

Abstract: In our investigation of rare earth sulfides in the AE-RE-Sn-S (AE=alkaline-earth, RE=rare earth) system, three isostructural quaternary sulfides have been obtained. These compounds adopt the Eu5Zr3S12 structure type and crystallize in the P-62m space group (no. 189); the crystal data are as follows: Sr2Y2.67Sn3S12, a =11.600(7)Å, c =3.948(3)Å, Z =1; Ca3La2Sn3S12, a =11.5997(6)Å, c =3.9407(4)Å, Z =1; Ca3Er2Sn3S12, a =11.448(3)Å, c =3.8780(11)Å, Z =1. Single-crystal analysis indicated that the crystal structures consist of three types of building block: RES7, AES6, and SnS6 units. The structure of Sr2Y2.67Sn3S12 is characterized by the trimer-chains along the c direction, which are connected into a 3-dimensional framework by the Sn atoms via S(1), S(2), and S(3), with Sr atoms filling in the channels along the c direction. The optical band gap of 1.45eV for Ca3La2Sn3S12 was deduced from the diffuse reflectance spectrum. [Copyright &y& Elsevier]

Abstract: In our investigation of non-centrosymmetric rare earth sulfides in the La3AgSnS7/KBr, LaAlGeS5/NaBr, HoAlGeS5/KBr, ErAlGeS5/NaBr, Er3AgGeS7/KBr and La3NaSnS7/NaBr systems, five compounds belonging to the R6B2C2Q14 family have been obtained. These compounds crystallize in the P63 space group, and the crystal data are as follows—La3AgSnS7: a =10.3780(15)Å, c =5.9900(12)Å, Z =2; La3Ge0.25GeS7: a =10.2970(15)Å, c =5.8120(12)Å, Z =2; Ho3Ge0.272(10)GeS7: a =9.6480(14)Å, c =5.7920(12)Å, Z =2; Er3Ge0.330(10)GeS7: a =9.5930(14)Å, c =5.8490(12)Å, Z =2; La3Sn0.25SnS7: a =10.2770(15)Å, c =6.0030(12)Å, Z =2. Single-crystal analysis indicated that the crystal structures consist of three types of building block: LnS n , MS4, and AgS3 (for La3AgSnS7) or MS6 units (for Ln3M x MS7, Ln=La, Ho, Er; M=Ge, Sn; 1/4≤ x ≤1/2), as any other compounds belonging to the R6B2C2Q14 family. Ln3M x MS7 (Ln=La, Ho, Er; M=Ge, Sn; 1/4≤ x ≤1/2) are deficient compounds with the B sites occupied partly by M(II), and/or M(IV). [Copyright &y& Elsevier]

Abstract: High-quality single crystals of RbInS2, CsInS2 were isolated from the halide flux as a major phase of the repeated fusion of CaS and In2S3 followed by slow cooling. RbInS2 and CsInS2 are practically isostructural with KInS2. RbInS2: C2/c, a =11.071(6)Å, b =11.068(1)Å, c =15.610(7)Å, β =100.36(3)°, V =1882(2)Å3, Z =16, d x =3.74g/cm3, R =6.38%, R w =6.42%. CsInS2: C2/c, a =11.197(3)Å, b =11.158(3)Å, c =16.358(4)Å, β =99.92(2)°, V =2013(2)Å3, Z =16, d x =4.12g/cm3, R =5.60%, R w =6.20%. The AInS2 (A=Rb, Cs) structure is characterized by double layers of vertex-sharing [In4S10] units that each consists of four [InS4] polyhedra. The charge-balancing alkali-metal cations are stuffed into the channels created by the packing of these anionic [In4S10] blocks. The optical reflectance measurements show a band gap of 3.3eV for RbInS2 and 3.4eV for CsInS2, suggesting that both are semiconductors. [Copyright &y& Elsevier]

Two new quaternary rare-earth chalcogenides, KHo2CuSe4 and KEr2CuSe4, were synthesized from the reactions of elements and binary selenides via a two-step flux technique. Single-crystal X-ray diffraction analyses indicate that both compounds crystallize in the orthorhombic KGd2CuS4 structure type with the space group Cmcm (No. 63) and Z=4. The indexed lattice constants and final R factors are as follows: KEr2CuSe4, a=4.061(1) A˚, b=13.748(4) A˚, c=14.150(3) A˚, V=790.1(3) A˚3, R=0.040, Rw=0.051; KHo2CuSe4, a=4.090(2) A˚, b=13.829(3) A˚, c=14.234(5) A˚, V=805.2(6) A˚3, R=0.046, Rw=0.052. The KLn2CuSe4 structure consists of three different building blocks: KSe6 trigonal prisms, LnSe6 octahedra and CuSe4 tetrahedra. The structure is characterized by edge-shared double octahedral Ln2Se10 units that are condensed into infinite chains along the a axis via trans-edge sharing. These double chains are further linked into a puckered layer in the a–b plane via edge-sharing and another corrugated layer in the a–c plane via corner-sharing with neighboring chains. Consequently, the structure actually forms a three-dimensional framework with additional feature from vertex-sharing CuSe4 tetrahedral chains. The K+ cations, located at the cavities defined by Se atoms, are filled in the channels along the a direction to provide appropriate Coulomb traps. Infrared spectra for both compounds show no absorption peaks between 4000 and 500 cm−1, which suggests an optical transparency in the long-wavelength infrared region. [Copyright &y& Elsevier]