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A new ternary phosphidopolysilicate (IV), KSi2P3, has been synthesized by high temperature solid state reaction. The compound crystallizes in a new structure type in the monoclinic space group C2/c with a=10.1327(5)Å, b=10.1382(5)Å, c=21.1181(10)Å, β=96.88(0)°, and Z=8. In the structure, all SiP4 tetrahedra are connected with each other by corner-sharing P atoms to form layers, which are stacked along c direction and separated by K+ cations. The two-dimensional structure of KSi2P3 contrasts with those of the two known members in the ternary A/Si/P (A=alkali metal) system, namely Na5SiP3 (zero-dimensional) and K2SiP2 (one-dimensional), which contains less amount of Si. The band gap deduced from UV–vis–IR diffuse reflectance spectrum is 1.72eV. [ABSTRACT FROM AUTHOR]

Abstract: A new series of transition-metal rare-earth chalcogenides, Ln 3FeGaQ7 (Ln=Nd, Sm, Gd, Dy, Q=S; Ln=Nd, Gd, Dy, Q=Se), have been synthesized by solid state reactions. They are isostructural and crystallize in the space group P63. They adopt a three-dimensional framework composed of LnQ7 monocapped trigonal prisms with the interesting [FeS3]4− chains and isolated GaQ4 tetrahedra lying in two sets of channels in the framework. Magnetic susceptibility measurements on Ln 3FeGaQ7 (Ln=Gd, Dy; Q=S, Se) indicate that they are paramagnetic and obey the Curie–Weiss law. Based on the diffuse reflectance spectra, Ln 3FeGaQ7 (Ln=Gd, Dy; Q=S, Se) should have band gaps smaller than 0.5eV. Electronic conductivity measurement on Dy3FeGaSe7 demonstrates semiconducting behavior with σ 300=0.124S/cm. The first-principles calculations were also performed to study the electronic structures of these compounds. [Copyright &y& Elsevier]

In this study, ordered mesoporous nanosheet SAPO-11 molecular sieves were synthesized using uncalcined SBA-15 molecular sieves as a Si source. The effects of different Si sources on the structure and properties of SAPO-11 molecular sieves were examined, and their growth mechanism was elucidated. An electrostatically polarized region was formed between a P123 template (triblock copolymer) contained in uncalcined SBA-15 and two-dimensional channels of SBA-15 molecular sieves. When AlO 2 − and PO 2 + species diffused into this region, its electrostatic polarization promoted the preferential growth of SAPO-11 molecular sieves along the c -axis, which contained a large number of exposed catalytically active sites with acidic properties. During the isomerization of long-chain alkanes, the synthesized sieves exhibited high isomerization activity and selectivity. When the conversion rate of n -dodecane reached 87.96%, the yield of i -dodecane was 68.08%, and the yield of multi-branched i -dodecane was 31.65%. Mechanism illustration of ordered mesoporous SAPO-11 with nanosheets morphology. [Display omitted] • Ordered mesoporous nanosheet SAPO-11 sieves are synthesized from uncalcined SBA-15. • A preferential growth mechanism of nanosheet SAPO-11 sieves is proposed. • Ordered mesoporous nanosheet SAPO-11 sieves expose more pore active sites. • Hydroisomerization of long-chain n -alkanes is investigated. [ABSTRACT FROM AUTHOR]