Junwei Ye

Preparation of sintered foam materials by alkali-activated coal fly ash

Coal fly ash from coal fired power stations is a potential raw material for the production of ceramic tiles, bricks and blocks. Previous works have demonstrated that coal fly ash consists mainly of glassy spheres that are relatively resistant to reaction. An objective of this research was to investigate the effect of alkali on the preparation process of the foam material. Moreover, the influence of foam dosage on the water absorption, apparent density and compressive strength was evaluated. The experimental results showed that homogenous microstructures of interconnected pores could be obtained by adding 13 wt.% foaming agent at 1050 degrees C, leading to foams presenting water absorption, apparent density and compressive strength values of about 126.5%, 0.414 g/cm(3), 6.76 MPa, respectively.

Diversification of hydrothermal reaction products induced by temperature: syntheses, structures and properties of four La(III)–Cu(II) metal frameworks constructed from rod-shaped molecular building blocks

The hydrothermal reaction of La(III), Cu(II) and 5-nitroisophthalic acid (H2NIPH) at different temperatures produced four novel coordination polymers, [LaCu(NIPH)(ONIPH)(H2O)4].H2O (1), [La2Cu(NIPH)4(H2O)6] (2), [La2Cu(NIPH)4(H2O)2] (3) and [LaCu(NIPH)2(HNIPH)(H2O)2].2H2O (4), (HONIPH = 2-hydroxy-5-nitroisophthalate), these 2D and 3D frameworks are the first La(III)-Cu(II) heterometallic frameworks based on infinite rod-shaped molecular building blocks. In 1, a 2D layer is composed of infinite La-O-C-O-Cu rods consisting of alternating [La2O14(CO2)2] and [Cu2O8] units by corner sharing. The 3D frameworks of 2-4 are constructed from different rod-shaped molecular building blocks, which are linked by NIPH ligands to form a pcu-type rod packing arrangement. Interestingly, HONIPH came from the in situ hydroxylation of H2NIPH in the hydrothermal reaction.

A magnesium carbonate recyclable template to synthesize micro hollow structures at a large scale

A facile strategy by using magnesium carbonate as the recyclable template has been developed to synthesize a variety of uniform inorganic hollow structures whose composition, size and shape can be readily modulated to generate interesting structures such as TiO(2), Al(2)O(3), SiO(2), Gd(2)O(3) and NiO microtubes and TiO(2), SiO(2) hollow microboxes.

Synergistic Flame-Retarded Effect of Synthetic Dawsonite on an EVA/Magnesium Hydroxide System

A novel halogen-free flame-retardant system composed of dawsonite and magnesium hydroxide was used for flame-retarded ethylene vinyl acetate. The thermal and fire properties of flame-retarded ethylene vinyl acetate system were evaluated by thermagravimetric analysis (TGA), limiting oxygen index (LOI) and UL-94 test while the structure of combustion residue was characterized by scanning electron microscopy (SEM). The highest LOI value and the V-0 grade of the composites were attained by the 5 wt% incorporation of dawsonite. These advancements are ascribed to the char stabilizer effect of fibrous-like combustion residue of dawsonite leading to increased strength of the residue.

Constructing hierarchical architectures of Eu3+-doped Mg3B2O6 for tunable luminescent properties

Two novel hierarchical architectures, flower-like and urchin-like MgBO2(OH), were facilely fabricated through a hydrothermal process, in the absence of any surfactant or template. Mg3B2O6 can be obtained by thermal decomposition of the MgBO2(OH) precursor with the morphology well-retained. These unique Mg3B2O6 assemblies were composed of uniform nanosheets and nanobelts, respectively. Under UV excitation, Eu3+-doped Mg3B2O6 shows a strong red emission corresponding to 5D0 → 7FJ (J = 1,2,3) transition of Eu3+. Interestingly, variable architectures of Mg3B2O6:Eu3+ from flower-like to urchin-like displayed tunable emission from 592 nm (5D0 → 7F1) to 611 nm (5D0 → 7F2) through the altering of symmetry of the crystal field around Eu3+ ions. The present architectures are envisaged to be potential candidates for fluorescent lamps and field emission displays.

Morphology-controlled assembly and enhanced emission of fluorescence in organic nanospheres and microrods based on 1,2-diphenyl-4-(4-dibenzothienyl)phenyl-1,3-cyclopentadiene

Fluorescent organic nanospheres, pod-like connecting spheres and microrods based on 1,2-diphenyl-4-(4-dibenzothienyl)phenyl-1,3-cyclopentadiene (DPCP) have been prepared via controlling the solvent composition. The influence of concentration, surfactants and solvents on the morphologies of products was examined. The formation of particles with different morphologies could be attributed to the solubility-controlled crystalline nucleation. Single crystal X-ray analysis reveals that the molecule of DPCP has a non-coplanar geometry, and two molecules are packed to form a dimer as an X-aggregate. Further, one-dimensional chains of DPCP additionally avoided the maximum face-to-face stacking. The solution of DPCP in methanol has weaker emission with a peak at 455 nm, however, the nanospheres, pod-like connecting spheres and microrods exhibited remarkably enhanced fluorescence emission with peaks at 447, 448 and 468 nm, respectively. Additionally, fluorescence change behavior was further verified by DFT calculation and time-resolved emission decay measurements.

Directed tuning of nanostructure from 1D to 3D by doping diverse valent cations

We design an unconventional strategy for controlling the nanostructure evolution of magnesium hydroxide from lamellar to rose-like, then to torispherical species by introducing diverse valent cations (Zn2+, Al3+, Sn4+). Lattice distortion induced by invasive cations would be responsible for the morphology transformation of metal hydroxide.

Tricarbon­yl[η5-2-(methyl­diphenyl­phosphanium­yl)-1,3,4-triphenylcyclo­penta­dienyl]molybdenum(0)

The title compound, [Mo(C36H29P)(CO)3], contains an Mo0 atom with a typical piano-stool coordination defined by the phosphonium cyclopentadienylide ligand η5-1-(methyldiphenylphosphaniumyl)-2,3,5-triphenyl-2,4-cyclopentadien-1-yl and by three carbonyl groups. The distance between the Mo0 atom and the cyclopentadienyl ring is 2.0616u2005(13)u2005Å.

catena-Poly[[aqua­dipyridine­copper(II)]-μ-fumarato]

The title compound, [Cu(C4H2O4)(C5H5N)2(H2O)]n, is a one-dimensional coordination polymer based on pyridine and fumarate ligands. Each CuII cation is coordinated by two carboxylate O atoms belonging to two fumarate anions, two N atoms from two pyridine molecules and one water molecule, in a square-based pyramidal geometry. Each fumarate anion bridges two CuII cations through the two carboxylate groups in a bis-monodentate fashion to form a one-dimensional polymeric chain along the c axis. Neighbouring chains are linked together to form a two-dimensional network parallel to the ac plane via hydrogen bonding interactions between uncoordinated carboxylate O atoms and coordinated water molecules of adjecent chains.