Papers by Author: Chun Hua Lu

Abstract: Conical arrays of polydimethyl siloxane were fabricated by duplicating the morphology of needle tips. The prepared cones have periodic order and regular shape, with the bottom diameter of about 80 μm and height of about 250 μm. Due to their special structure, the conical arrays of polydimethyl siloxane exhibited broadband anti-reflective property. Compared with smooth surface, they could reduce the reflection of incident electromagnetic wave at ultraviolet, visible and near-infrared region. The specular reflectance was lower than 0.75% in the range of 250-2600 nm. The prepared PDMS cones have potential to be applied for antireflective devices. The method was simple for mass production of PDMS cones at low cost.

Abstract: The novel photocatalyst of α-Fe₂O₃/Sb-doped SnO₂ (ATO) nanocomposites were fabricated by two-step process of hydrothermal and precipitation method. The structure, size, magnetic behavior and absorption property were characterized by XRD, TEM, VSM and UV-Vis absorption spectrum. The composites with low mole ratio of ATO have more pronounced photocatalytic activities. The optimum photocatalytic activity in our experiments appears at the mole ratio of n_Fe:n_Sn=1:0.25. The α-Fe₂O₃/Sb-doped SnO₂ nanocomposites have better photocatalytic activities than α-Fe₂O₃/SnO₂ nanocomposites. The results show that the doping of Sb ions can improve the capture ability of electrons and consequently enhance the photocatalytic activities of the composite system.

Abstract: The novel kind flowerlike mesoporous spheres of calcium silicate hydrate (CaO•SiO2•H2O, CSH) have been synthesized by co-precipitation method on based with water/alcohol/calvital/ tetraethyl orthosilicate (TEOS) system. The synthesized CSH were applied as a carrier to study the loaded behaviors of ibuprofen(IBU),was used to investigate the drug loading behavior of the CSH for different times has been also discussed. The drug loading capacities(DLCs) of CSH loaded for 12h has reached 116.78wt.%. The structural, morphological and textural properties were investigated by SEM, FTIR, TG and BET. The results show that it would be a good candidate as drug carrier for bone repair.

Abstract: Layered SmBaCo₂O_5+δ with the cation-ordered double perovskite structure were synthesized by the solid-state reaction route and characterized by thermal analysis, X-ray diffraction, infrared spectrum, electrical conductivity and infrared emissivity. The Sm_1-xBa_xCoO₃ (SBCO) system shows the different crystal structures with the variation of barium content, which results in the different electrical behavior. The electrical conductivity reaches maximum when x is 0.5 with SmBaCo₂O_5.54 phase. The infrared absorption occurs at about 600 cm^-1 for all the samples which were attributed to Co-O stretching modes. The peak shifted to a lower frequency with the increase of doping level. In addition, the comparison of electrical and emissivity measurements suggested that variation of infrared emissivity is in agreement with the electrical properties.

Abstract: Sm₂(WO₄)₃ crystals have been synthesized through liquid-phase reaction. The structure, morphology and optical properties of the products have been investigated by Fourier transform infrared spectroscopy (FTIR), X-ray diffractometer, SEM, and spectrofluorometer, respectively. The compound crystallized in the monoclinic hexagonal system, space group C2/c. Heat treat promoted the crystallization and regulated the micro-structure of Sm₂(WO₄)₃. In the Sm₂(WO₄)₃ host, the WO₄^2- group could transfer the energy of near-UV light to Sm³⁺ ions, emitting blue, green and red light at 429 nm (⁶P_5/2→⁶H_5/2), 453 nm (⁴G_9/2→⁶H_5/2), 495, 507 nm (⁴G_7/2→⁶H_5/2), 563 nm (⁴G_5/2→⁶H_5/2), 601 nm ( ^4G_5/2→⁶H_7/2) and 649 nm ( ^4G_5/2→⁶H_9/2), respectively. The ratio of blue, green and red light was appropriate to achieve white light. The Sm₂(WO₄)₃ powders have potential to act as UV absorber for solar cell and may be helpful to the development of white light LED.

Abstract: In this paper, setting 1.06 μm Gaussian modulated pulse electromagnetic wave as irradiation sources, the influences of structural parameters on reflectivity are analyzed by finite different time domain (FDTD) method. The results show that the filled factor and height are key factors for circular tube relief structure with non absorption. The optimal height could be set to 0.2 μm, which is one odd time of the ratio of incident wavelength λ and four equivalent refractive index 4N, then the best filled factor is between 0.7 and 0.9, the ratio of inner and outer diameter could be set between 0.4 and 0.6, and the structure period has little significant influence. Compared with cylinder solid structure, it has been discovered that circular tube hollow structure could weaken the backward energy of electromagnetic wave, and it would be more suitable for antireflection structure than solid cylinder structure. Moreover, we design two another circular tube relief structures simulations with different extinction coefficients, it is found that the reflectivities are lower up to 0.00016% than the non absorption one.

Abstract: For the first time, nano-scale rods of NaLaxYb9-x(SiO4)6O2 (x=1,3,5,7,9) crystals (NLS) activated with Er3+ have been synthesized through a mild hydrothermal conditions with subsequent calcination. The as-obtained products were characterized by the X-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy (FTIR). The results indicate that the compound has an apatite structure and crystallizes in the hexagonal system, space group P63/m. The excitation spectrum and emission spectrum were also emplyed to investigate the optical properties of the nano-rods. The Er3+ doped NLS exhibit green/red up-conversion luminescence under excitation with a diode laser at 980 nm.

Abstract: The amorphous calcium phosphate (ACP)/tricalcium silicate (Ca3SiO5, C3S) composite powders were synthesized in this paper. The exothermal behavior of C3S determined by isothermal conduction calorimetry indicated that the ACP could be synthesis by chemical precipitation method during the induction period (stage II) of C3S. The composite powders were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). The results indicated that nanosized ACP particles deposited on the surface of C3S particles to form core-shell structure at pH=10.5, and the nCa/nP of ACP could be controlled between 1.0 and 1.5. The core-shell structure is stable after sintered at 500 oC for 3 h to remove the β-cyclodextrin (β-CD). As compared with the irregular C3S particles (1~5 μm), the composite powders particles are spherical with a diameter of 40~150 μm. Therefore, to obtain the smaller size of composite powders, it is expected to avoid the aggregate of C3S particles in the aqueous solution by addition of dispersant. As compared with C3S, the composite powders may contribute better injectability, strength and biocompatibility.

Abstract: TiO2, ZrO2 and titanium oxide in deficiency oxygen environment were used to modify the surface of biomedical NiTi stents. The coatings were prepared by vacuum deposition. The surface microstructures and characteristics, blood compatibility of the modified stents in simulated body fluids were assessed using scanning electron microscopy (SEM), hemolysis test, coagulation test and blood platelet adhesion test. The hemocompatiblity of the modified stents were all improved by layer coating. Enhancement of blood compatibility was believed to stem from the improved surface water affinity and hemolysis resistance of the layer, and titanium oxide in deficiency oxygen environment displayed better. This study indicated that layer coating was a promising effective modification method for improving the surface properties of biomedical NiTi alloy intravascular stents. As a coating materials，titanium oxide in deficiency oxygen environment was better than TiO2 and ZrO2.

Abstract: In this article, Sm(Sal)xPhen, SmyY1-y(Sal)3Phen were synthesized and its films were prepared. They were characterized by infrared spectra (IR), ultra-violet visible spectrometer (UV), X-ray diffraction (XRD) and fluorescence spectroscopy. Sm/Y complexes and its mixture doped with the polyvinyl alcohol (PVA) showed photoluminescence at the wavelength of 646 nm. There was an excellent compatibility among Sm/Y complexes, the polyvinyl alcohol (PVA) and dimethyl sulphoxide (DMSO), which were used to prepare the resin film. The results indicated that Sm/Y rare earth light conversion films were better light conversion films with good compatibility in resins, and with emission wavelength suitable for plants’ photosynthesis.