Advanced Materials Research Vols. 299-300

Abstract: This paper investigated the influence of various processing parameters of atmospheric pressure plasma jet (APPJ) on the etching behavior of PVA films. The etching rate increased as output power, and moisture regain increased. As the treatment time increased, the etching rate increased initially and then decreased. Atomic force microscopy (AFM) results showed that the surface roughness varied as the moisture regain (MR) (2.45%, 9.32%, and 78.31%, respectively) of PVA films changed during APPJ treatment. It was found that higher moisture regain and lower thermal conduction of underlayer had negative effect on the solubility of plasma treated PVA films.

Abstract: (Gd_1-x,Dy_x)₂O₂SO₄ phosphors were synthesized by a homogeneous precipitation method from commercially available Gd₂O₃, Dy₂O₃, H₂SO₄ and Urea ((NH₂)₂CO) starting materials. XRD analysis shows that the amorphous precursor can be transformed into pure Gd₂O₂SO₄ phase by calcining at 900 °C for 2 h in air. Photoluminescence (PL) spectroscopy reveals that the strongest and second emission peaks are located at 575 nm and 485 nm under 277 nm UV light excitation, which corresponds to the ⁴F_9/2→⁶H_13/2 and the ⁴F_9/2→⁶H_15/2 transitions of Dy³⁺ ions, and both transitions of Dy³⁺ ions have a single exponential decay behavior. The quenching concentration of Dy³⁺ ions is 1 mol%. The CIE chromaticity coordinate and the color temperature of (Gd_0.99,Dy_0.01)₂O₂SO₄ phosphor are (0.306, 0.379, 0.315）and 6546 K, respectively.

Abstract: The properties of nano Al₂O₃ modified electrolytic phosphating film have been studied through using the accelerated corrosion test, electrochemical testing techniques, scanning electron microscope (SEM) and X-ray diffraction (XRD) .The results show that, after adding nano- Al₂O3 in electrolytic phosphating bath , morphology of phosphating film surface turned dense flake crystallization from needle crystal morphology of free-adding nano- Al₂O₃ powder, and the value of impedance of the Al₂O₃ incorporated phosphate coating was increased obviously.When the nano- Al₂O₃ concentration was 15mg / L in electrolytic phosphating bath, the value of impedance of the coating is approximately two times larger than the phosphating coating directly formed on the low carbon steel.The corrosion resisting time of the coating was more than 420 s by CuSO₄ dripping test, and the corrosion current density of the phosphating sample was 1.164μA/cm²，in 3.5% NaCl solution, the corrosion inhibition efficiency reached 96.7%.

Abstract: A simple method of preparing nanotemplates with special microstructures by polystyrene-block-poly(methyl methacrylate) (PS-b-PMMA) surface micelles was researched in this study. The self-assembly of surface micelles adsorbed on mica when exposed to the vapors of toluene, acetone and water was studied by atomic force microscopy (AFM) in detail. Results indicate the irregular and spherical structures can be obtained in the vapors of toluene and acetone respectively. Various microstructures ranging from starfish-like to chrysanthemum, torus, cylinder and hat structures can be obtained in water vapor for different time. The special microstructures of PS-b-PMMA can be used as nanotemplates to prepare nanomaterials with special nanostructures.

Abstract: High-transparent Eu³⁺-doped yttrium lanthanum oxide ceramics were fabricated with nanopowders and the highest transmittance in the visible light wavelength region reaches 78%. The Eu³⁺-doped transparent ceramics exhibited a broad absorption band around 240 nm, a sharp red emission at 611 nm under X-ray excitation and the fluorescent decay time of 0.96 ms. It is expected to be a potential polycrystalline scintillation material for the applications in medical-imaging detectors.

Abstract: Yb³⁺-doped Y₂O₃ and (Y_0.9Sc_0.1)₂O₃ transparent ceramics were fabricated, and their microstructures, structural and spectral properties were investigated. Sc₂O₃ can effeciviely inhibit the excessive grain growth in Yb:Y₂O₃ ceramics, and increased the transparency. The lattice parameter of Yb:(Y_0.9Sc_0.1)₂O₃ became small due to introducing of Sc³⁺ ions. The emission bands of Yb:(Y_0.9Sc_0.1)₂O₃ ceramics are inhomogeneously broadened compared to Yb:Y₂O₃. The broad emission bandwidths of Yb:(Y0.9Sc_0.1)₂O₃ ceramics are favorable for the generation of ultrashort mode-locked pulse laser.

Abstract: Pr³⁺: La₂O₃ ceramics was fabricated by conventional ceramics processing and sintered without pressure in H₂ atmosphere. The structure and spectroscopic properties of the samples were investigated. The strongest excitation peak is detected at 291 nm, which is corresponding to the 4f−5d absorption band of Pr³⁺ ion. Pr³⁺ emits green light in La₂O₃ ceramics, the major emission peak located at 512 nm belongs to ³P₀→³H4 transition. Pr³⁺:La₂O₃ owns hexagonal structure and is unstable in air condition, it is easy to absorb water vapor to form La(OH)₃.

Abstract: LaAlO₃ translucent ceramics were fabricated with solid-state reaction method and sintered in vacuum condition. The powders are synthetized at 1200°C. There are almost no pores in the grains of ceramics sintered at 1750 °C. But the ceramics have few La₂O3 second phase. The highest transmittance is 22%. The low transmittance may be caused by scattering losses of La₂O₃ second phase.

Abstract: Highly transparent (Ho_0.01La_0.10Y_0.89)₂O₃ transparent ceramics were fabricated by the conventional ceramics processing with nanopowders. The microstructure, the optical properties and the spectroscopic properties of (Ho_0.01La_0.10Y_0.89)₂O3 ceramics were investigated. (Ho_0.01La_0.10Y_0.89)₂O3 ceramics with the grain size of ~50 μm were obtained by sintering at 1530 °C for 45 h. The highest in-line transmittance reaches 65%. The emission peak located at 2 μm wavelength indicates (Ho_0.01La_0.10Y_0.89)₂O3 transparent ceramics is suitable for 2 μm laser gain medium.

Abstract: The effect of Y addition on the average grain size and mechanical properties of Ni-Mn-Ga magnetic shape memory alloys is researched by means of optical microscope, compressive test and scanning electron microscope (SEM) in the paper. The results show that Y addition refines the grains of Ni-Mn-Ga alloy significantly and significantly enhances the compressive strength and maximum compressive strain. In addition, the fracture type changes from typical intergranular crack to transgranular crack gradually with Y addition.