Growth of NaBi(WO4)2 crystal by modified-Bridgman method

NaBi(WO₄)₂ (NBW) crystals have been grown for the first time by modified-Bridgman method. Influences of some factors on the crystal growth process are discussed. X-ray powder diffraction experiments show that the unit cell parameters of NBW crystal are a=b=0.5284 nm, c=1.1517 nm, and V=0.3215 nm³. The differential thermal analysis shows that the NBW crystal melts at 923°C.     

Synthesis and Crystal Structures of Spiro[1,3-Dihydroperimidine-2,9′-Fluorene] and its Co-Crystal with 9-Fluorenone

Abstract  

The crystal structures of the new compounds spiro[1,3-dihydroperimidine-2,9′-fluorene] (1), and co-crystal (2) consists of 1 and 9-fluorenone were obtained by single crystal X-ray diffraction. Compound 1 crystallizes in the orthorhombic space group Pbca, with lattice parameters: a = 14.914(9) ?, b = 16.2126(8) ?, c = 26.4850(14) ? and Z = 16. Co-crystal 2 crystallizes in the orthorhombic space group Pca2(1), with lattice parameters: a = 18.0732(9) ?, b = 7.7216(4) ?, c = 17.8262(9) ? and Z = 4. Details of the synthesis, structures, thermal and spectroscopic properties of the new compounds are discussed.     

Surface morphology,structural and optical properties of polar and non-polar ZnO thin films: A comparative study

The polar and non-polar ZnO thin films were fabricated on cubic MgO (1 1 1) and (0 0 1) substrates by plasma-assisted molecular beam epitaxy. Based on X-ray diffraction analysis, the ZnO thin films grown on MgO (1 1 1) and (1 0 0) substrates exhibit the polar c-plane and non-polar m-plane orientation, respectively. Comparing with the c-plane ZnO film, the non-polar m-plane ZnO film shows cross-hatched stripes-like morphology, lower surface roughness and slower growth rate. However, low-temperature photoluminescence measurement indicates the m-plane ZnO film has a stronger 3.31 eV emission, which is considered to be related to stacking faults. Meanwhile, stronger band tails absorbance of the m-plane ZnO film is observed in optical absorption spectrum.     

A versatile kinetics-controlled coating method to construct uniform porous TiO2 shells for multifunctional core-shell structures

The development of a simple and reproducible route to prepare uniform core@TiO(2) structures is urgent for realizing multifunctional responses and harnessing multiple interfaces for new or enhanced functionalities. Here, we report a versatile kinetics-controlled coating method to construct uniform porous TiO(2) shells for multifunctional core-shell structures. By simply controlling the kinetics of hydrolysis and condensation of tetrabutyl titanate (TBOT) in ethanol/ammonia mixtures, uniform porous TiO(2) shell core-shell structures can be prepared with variable diameter, geometry, and composition as a core (e.g., α-Fe(2)O(3) ellipsoids, Fe(3)O(4) spheres, SiO(2) spheres, graphene oxide nanosheets, and carbon nanospheres). This method is very simple and reproducible, yet important, which allows an easy control over the thickness of TiO(2) shells from 0 to ~25, ~45, and ~70 nm. Moreover, the TiO(2) shells possess large mesoporosities and a uniform pore size of ~2.5 nm, and can be easily crystallized into anatase phase without changing the uniform core-shell structures.     

The morphologies and optoelectronic properties of delafossite CuFeO2 thin films prepared by PEG assisted sol–gel method

Single phase delafossite CuFeO₂ thin films were synthesized by a simple sol–gel method. The influence of polyethylene glycol (PEG) on the morphology and optoelectronic properties of the films was studied by addition of 1.0 g PEG in 10 ml precursor solution. The crystal sizes of the derived CuFeO₂ films with and without addition of PEG were 49 nm, but the sample with addition of PEG (labeled as CFO-PEG) showed weaker c-axis orientation growth. The sample without addition of PEG (labeled as CFO) showed a compact surface without detectable pores and had a thickness around 50 nm. However, the sample CFO-PEG exhibited a porous surface with worm-like grains in nanometric scale and had a thickness around 310 nm. Enhanced absorbance in UV–vis region was observed for the sample CFO-PEG which might ascribe to both the thickness and porous surface. The optical direct bandgaps at near-UV were estimated to be ~3.0 and 3.38 eV for the sample CFO-PEG and CFO, respectively. Though the porous surface of CFO-PEG has improved the absorbance in UV–vis region, the resistivity has also been increased due to the homogeneous distribution of interspaces between the worm-like grains, which makes the incident photon to current efficiency of CFO-PEG lower than that of CFO.     

Study on the anti‐sulfur‐poisoning characteristics of platinum–acetylide–phosphine complexes as catalysts for hydrosilylation reactions

A series of platinum–acetylide–phosphine complexes were synthesized and their anti‐sulfur‐poisoning characteristics investigated. In comparison with Speier's and Karstedt's catalysts, the platinum–acetylide–phosphine complexes exhibited both higher catalytic activity and selectivity for the β‐adduct for the hydrosilylation reactions under the same conditions. Furthermore, the complexes also exhibited a strong ability to resist to sulfur‐poisoning. This indicated that the alkyne ligands containing the silyl group had a strong impact on the hydrosilylation reaction. Copyright © 2014 John Wiley & Sons, Ltd.