Deposition and characterization of binary Al2O3/SiO2 coating layers on the surfaces of rutile TiO2 and the pigmentary properties

Binary Al₂O₃/SiO₂-coated rutile TiO₂ composites were prepared by a liquid-phase deposition method starting from Na₂SiO₃·9H₂O and NaAlO₂. The chemical structure and morphology of binary Al₂O₃/SiO₂ coating layers were investigated by Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, TG-DSC, Zeta potential, powder X-ray diffraction, and transmission electron microscopy techniques. Binary Al₂O₃/SiO₂ coating layers both in amorphous phase were formed at TiO₂ surfaces. The silica coating layers were anchored at TiO₂ surfaces via Si-O-Ti bonds and the alumina coating layers were probably anchored at the SiO₂-coated TiO₂ surfaces via Al-O-Si bonds. The formation of continuous and dense binary Al₂O₃/SiO₂ coating layers depended on the pH value of reaction solution and the alumina loading. The binary Al₂O₃/SiO₂-coated TiO₂ composites had a high dispersibility in water. The whiteness and brightness of the binary Al₂O₃/SiO₂-coated TiO₂ composites were higher than those of the naked rutile TiO₂ and the SiO₂-coated TiO₂ samples. The relative light scattering index was found to depend on the composition of coating layers.     

Synthesis and regularities of combustion of acetoxymethylnitroamines. Impact sensitivity of secondary alkylnitroamines

The use of the nitrolysis of cyclic amines and of the direct synthesis from primary nitroamines made it possible to obtain acetates of methylolnitroamines of general formula AcO(CH₂NNO₂) _n R(n = 1–6). A number of high explosives, nitroamines, were synthesized: DNA ((CH₃NNO₂)₂CH₂), DMNA ((CH₃)₂NNO₂), DNA-2 ((CH₃NNO₂CH₂)₂), TRIS ((CH₃NNO₂CH₂)₂NNO₂), and TETRA ((CH₃NNO₂CH₂NNO₂)₂CH₂). The regularities of the combustion of the synthesized compounds were studied, and their characteristics were compared. Stress curve measurements were used to estimate the impact sensitivity of alkylnitroamines. A number of basic macroscopic characteristics of the nitroamines studied and nitroamine-ammonium perchlorate mixtures, including the heat of explosion. For comparison, the characteristics of regular high explosive are given.     

Structural and electronic effects in metallocene catalysts studied by x‐ray techniques

A series of metallocenes, namely, [Cp₂ZrCl₂], [(MeCp)₂ZrCl₂], [(nBuCp)₂ZrCl₂], [(iBuCp)₂ZrCl₂], [(tBuCp)₂ZrCl₂], [Et(Ind)₂ZrCl₂], [Et(IndH₄)₂ZrCl₂], and [MeSi₂(Ind)₂ZrCl₂)] were analyzed by extended x‐ray absorption fine structure (EXAFS) and x‐ray photoelectron spectroscopy (XPS). Complementary techniques, UV–vis spectroscopy and cyclic and differential pulse voltammetry, were employed to characterize the organometallic complexes. The catalysts were evaluated in ethylene polymerization, having methylaluminoxane (MAO) as the cocatalyst, and the resulting polymers were characterized by gel permeation chromatography. The structural and electronic effects caused by the coordination sphere around the metal center and their effects on the catalytic activity and polymer characteristics are discussed. Copyright © 2008 John Wiley & Sons, Ltd.     

The effect of 3-aminopropyltrimethoxysilane on the formation of NiFe2O4/SiO2 nanocomposites

NiFe₂O₄/SiO₂ nanocomposites were prepared using a sol–gel method with the addition of 3-aminopropyltrimethoxysilane (APS). Different phases and morphologies of NiFe₂O₄/SiO₂ nanocomposites were obtained when different amounts of APS were used. The structural properties of the products were examined by X-ray diffraction (XRD) and transmission electron microscopy (TEM). Sheet-like morphology was observed at higher molar ratio of APS to NiFe₂O₄, while spherical NiFe₂O₄/SiO₂ nanoparticles separated from each other were formed at lower molar ratio of APS to NiFe₂O₄. The magnetic properties of the nanocomposites were also investigated, indicating that the interparticle interactions exhibit strong dependence on the molar ratio of APS to NiFe₂O₄.     

Raman characterizations and structural properties of the binary TeO2?WO3, TeO2?CdF2 and ternary TeO2?CdF2?WO3 glasses

The Raman spectroscopy technique was used to characterize the microstructure and the crystallization properties of the as‐cast and heat‐treated binary TeO₂ WO₃, TeO₂ CdF₂ and ternary TeO₂ CdF₂ WO₃ glasses and glass ceramics. The results were compared with those obtained by using the X‐ray diffraction technique. The effect of the WO₃ and CdF₂ contents on the TeO₂ glass network and the intensity ratios of the deconvoluted Raman peaks were determined. The shifts in the Raman band wavenumbers and the intensity values for each band were investigated. The Raman results indicated that the glasses were mainly formed by the [TeO₄] and [TeO₃] units. The [TeO₄] units convert to [TeO₃] units with the addition of WO₃ and CdF₂ into tellurite glasses. All the crystalline phases such as α‐TeO₂, δ‐TeO₂ and γ‐TeO₂ existing in the TeO₂ WO₃, TeO₂ CdF₂ and TeO₂‐ WO₃ CdF₂ glasses were determined. The transformation of the metastable γ‐TeO₂ phase into stable α‐TeO₂ was observed for the (1 − x)TeO₂ xWO₃ (where x = 0.15, 0.20, 0.25), 0.90Te₂ 0.10CdF₂, the 0.85TeO₂ 0.10CdF₂ 0.05WO₃ and 0.80TeO₂ 0.10CdF₂ 0.10WO₃ glasses, and the transformation of the metastable δ‐TeO₂ phase into the stable α‐TeO₂ was also observed for the TeO₂ CdF₂ WO₃ glass system. In addition, an unidentified phase formation, labeled ε, was determined. Copyright © 2009 John Wiley & Sons, Ltd.     

YBa2Cu3O7-x涂层导体的外延生长和性能对CeO2缓冲层的依赖性

利用倾斜衬底沉积法在无织构的金属衬底上生长了MgO双轴织构的模板层,在这一模板层上实现了YBa₂Cu₃O_7-x薄膜的外延生长.在外延YBa₂Cu₃O_7-x薄膜前,依次沉积了钇稳定的立方氧化锆和CeO₂作为缓冲层.利用X射线衍射2θ扫描、扫描、Ω扫描和极图分析测定了这些膜的结构和双轴织 关键词： 2Cu₃O_7-x镀膜导体')" href="#">YBa₂Cu₃O_7-x镀膜导体 2缓冲层')" href="#">CeO₂缓冲层 厚度依赖性 外延生长     

2∶17型快淬Sm-Fe-Cu-Si-C的硬磁性

研究了Sm₂Fe₁₅Si₂C和Sm₂Fe₁₄CuSi₂C化合物的结构与磁性,测量了化合物的居里温度T_C和饱和磁化强度M_s.通过对取向样品在磁场平行和垂直取向方向测量的磁化曲线的拟合得到了不同温度下化合物的磁晶各向异性场H_A和各向异性常数K₁和K₂.实验结果表明,Cu的     

A study of formation process of NiFe2O4 and ZnFe2O4 prepared bij oxalate coprecipitation

MFe₂(C₂O₄)₃*6H₂O (M=Ni, Zn) powders were prepared by oxalate coprecipitation. Using Mössbauer spectroscopy, XRD, DTA and TEM, the thermal decomposition of MFe₂(C₂O₄)₃*6H₂O and the formation process of NiFe₂O₄ and ZnFe₂O₄ were investigated.     

Ga2O3组分对Tm3+掺杂GeO2-Ga2O3-Li2O-BaO-La2O3玻璃的光谱性能影响

制备了Tm³⁺(8.0mol%)掺杂(77-x)GeO₂-xGa₂O₃-8Li₂O-10BaO-5La₂O₃(x=4,8,12,16)系列玻璃.系统地研究了Ga₂O₃从4mol%变化到16mol%时,玻璃的光谱性质与热学性质的变化规律.差热分析表明,随着Ga₂O₃含量的增加,锗酸盐玻璃的热稳定性增加.运用Judd-Ofelt(J_O)理论计算得到了Tm³⁺在不同Ga₂O₃含量的GeO₂-Ga₂O₃-Li₂O-BaO-La₂O₃玻璃中的J-O强度参数(Ω₂,Ω₄,Ω₆)及Tm³⁺各激发能级的自发跃迁概率、荧光分支比以及辐射寿命等光谱参量.在808nm激光二极管的激发下,测试并分析了Ga₂O₃对Tm³⁺荧光光谱特性的影响.随着Ga₂O₃从4mol%增加到16mol%,Tm³⁺在1.8μm处的荧光强度呈现先减弱后增强的特性.当Ga₂O₃含量大约在12mol%时,Tm³⁺在1.8μm处的荧光强度最弱,受激发射截面达到最小.还初步讨论了Ga₂O₃对玻璃结构与光谱参数的影响规律. 关键词： 3+掺杂锗酸盐玻璃')" href="#">Tm³⁺掺杂锗酸盐玻璃 光谱性能 Judd-Ofelt参数 热稳定性     

Preparation and characterization of inorganic colored coating layers on lamellar mica-titania substrate

The inorganic colored composite pigments, such as Fe₂O₃-, Bi₄Ti₃O₁₂-, and CoAl₂O₄-coated mica-titania composites, were prepared by hydrolysis of FeCl₃, Bi(NO₃)₃, and Co(NO₃)₂/Al(NO₃)₃ in the presence of mica-titania substrate and calcination at different temperatures. The inorganic coating layers on mica-titania substrate surfaces were explored by X-ray diffraction, scanning electron microscopy, Fourier transform infrared, and X-ray photoelectron spectroscopy. Dense and uniform Fe₂O₃ coating layers were formed on the surfaces of mica-titania substrates. At lower Bi₂O₃ loading, Bi₄Ti₃O₁₂ nanoparticles were formed on the surfaces of mica-titania substrates. But at higher Bi₂O₃ loading, Bi₄Ti₃O₁₂ nanosheets were formed and perpendicularly oriented to the substrate surfaces. CoAl₂O₄ nanosheets were formed on the mica-titania substrates and perpendicularly oriented to the substrate surfaces. The pigmentary performances of the inorganic composite pigments were analyzed by CIE, indicating that red, yellow, and blue colored pigments were achieved by coating Fe₂O₃, Bi₄Ti₃O₁₂, and CoAl₂O₄ on mica-titania substrate surfaces, respectively. The pigmentary performances of the inorganic composite pigments were significantly affected by the morphology and loading of inorganic coating layers.     

Bi离子掺杂GeO2-Al2O3-M(M=Na2O，BaO，Y2O3)玻璃的光学性质

用高温熔融法制备了Bi离子掺杂浓度为1mol%的GeO-B₂O₃-Na₂O (GBNB)，GeO₂-Al₂O₃-Na₂O(GANB)，GeO₂-Al₂O₃-BaO(GABB)和GeO₂-Al₂O₃-Y₂O₃(GAYB)玻璃.测定了样品玻璃的差热曲线、吸收、发射光谱及荧光衰减曲线.实验发现GBNB，GANB，GAYB，GABB的吸收边带逐步发生红移.由于这些吸收边带是由Bi³⁺的6s²电子到Bi⁵⁺ 6s⁰空轨道的跃迁引起.因此推断GBNB，GANB，GAYB，GABB玻璃中Bi⁵⁺离子的含量逐步增加.在GABB，GAYB，GANB三个样品中观察到发光中心约1220nm超宽带荧光发射.荧光强度从GABB，GAYB，GANB逐步减弱，荧光半高宽和荧光寿命逐步变小.这些超宽带的荧光归属为Bi⁵⁺离子的发光所致.从吸收与荧光光谱的变化，推断在GeO₂-Al₂O₃玻璃中引入BaO，Y₂O₃组分有利于Bi⁵⁺离子的形成.讨论了BaO，Y₂O₃化学组分对Bi离子在玻璃中的价态影响的内在机理. 关键词： 5+离子')" href="#">Bi⁵⁺离子 超宽带发光 吸收带 荧光寿命     

Syntheses,X‐ray crystal structures,and emission properties of protonated tripyridyltriazines and their ruthenium(II) complexes

A series of metal‐free compounds, ie, planar triprotonated triazine, triazineH₃Cl(PF₆)₂ ( 1 ), planar triprotonated triazineH₃Br(PF₆)₂ ( 2 ), and nonplanar monoprotonated triazineHPF₆ ( 3 ), were prepared. Abbreviations used are triazine = tri‐2‐pyridyltriazine. Ruthenium complexes [RuCl(bpy)(L)](PF₆), [RuCl(bpy)(L)](PF₆)₂, and [Ru(L)₂](PF₆)₂ were also prepared, where bpy is 2,2′‐bipyridine and L's are triazine ( 4 ) and monoprotonated triazine ( 5 ), respectively. Ruthenium complexes [Ru(triazine)₂](PF₆)₂ ( 6 ) were also prepared and crystallized. The X‐ray crystal structures of the 3 compounds 1 , 2 , and 3 and the complex 6 were determined. They were also characterized by electrospray ionization mass spectrometry, UV‐vis spectroscopy, and density functional theory calculations.     

Photocatalytic properties of lanthanide tungstates Ln2W2O9 (Ln=La,Pr, Nd,Sm, and Gd)

Lanthanide tungstates, Ln₂W₂O₉ (Ln=La, Pr, Nd, Sm, and Gd), were prepared via the polymerized complex method at 1273 K for 2 h, and their photocatalytic activities for hydrogen and oxygen evolution were investigated. Pt-loaded Gd₂W₂O₉ exhibited activity for H₂ evolution from an aqueous methanol solution under light irradiation (λ>300 nm). The remaining Ln₂W₂O₉ were inactive for H₂ evolution due to the influence of the Ln elements and their crystal structures. All Ln₂W₂O₉ were inactive for O₂ evolution from an aqueous AgNO₃ solution due to the lack of O₂ evolution sites on the surface.     

A novel blue-emitting phosphor: BaAl2B2O7: Pb

Pb²⁺ doped BaAl₂B₂O₇ materials were prepared by a solution combustion synthesis. The phase of the synthesized materials was determined using the powder X-ray diffraction. The photoluminescent properties of Pb²⁺ doped BaAl₂B₂O₇ materials were investigated using spectrofluorometer at room temperature. The emission and excitation bands of BaAl₂B₂O₇: Pb²⁺ were observed at 423 and 266 nm, respectively. The dependence of the emission intensity on the Pb²⁺ concentration for BaAl₂B₂O₇: Pb²⁺ was investigated. The Stokes shifts of BaAl₂B₂O₇: Pb²⁺ was calculated to be 13 953 cm⁻¹.     

Radiation damage produced in powder of α-(methylamino)isobutyric acid, α -aminoisobutyric acid methyl ester hydrochloride and diethylmalonic acid

The electron paramagnetic resonance spectra of γ-irradiated powders of α-(methylamino)isobutyric acid – CH₃NHC(CH₃)₂COOH, α -aminoisobutyric acid methyl ester hydrochloride – NH₂(CH₃)₂CCOOCH₃ HCl, and diethylmalonic acid – (CH₃CH₂)₂C(COOH)₂ have been investigated at room temperature. It has been found that γ -irradiation produces the (CH₃)₂C˙COOH radical in the first, the (CH₃)₂C˙COOCH₃ radical in the second and the (CH₃CH₂)₂C˙COOH radical in the third compound. The spectra were computer-simulated. The g values and the hyperfine coupling constants of the unpaired electron with the environmental methyl, methylene protons and OH proton were determined. The results were found to be in good agreement with the existing literature data and theoretical predictions.     

XPS investigation of diffusion of two-layer ZrO2/SiO2 and SiO2/ZrO2 sol–gel films

Two-layer ZrO₂/SiO₂ and SiO₂/ZrO₂ films were deposited on K9 glass substrates by sol–gel dip coating method. X-ray photoelectron spectroscopy (XPS) technique was used to investigate the diffusion of ZrO₂/SiO₂ and SiO₂/ZrO₂ films. To explain the difference of diffusion between ZrO₂/SiO₂ and SiO₂/ZrO₂ films, porous ratio and surface morphology of monolayer SiO₂ and ZrO₂ films were analyzed by using ellipsometry and atomic force microscopy (AFM). We found that for the ZrO₂/SiO₂ films there was a diffusion layer with a certain thickness and the atomic concentrations of Si and Zr changed rapidly; for the SiO₂/ZrO₂ films, the atomic concentrations of Si and Zr changed relatively slowly, and the ZrO₂ layer had diffused through the entire SiO₂ layer. The difference of diffusion between ZrO₂/SiO₂ and SiO₂/ZrO₂ films was influenced by the microstructure of SiO₂ and ZrO₂.     

Measurements and calculations of Ar-broadening parameters of water vapour transitions in a wide spectral region

The water vapour line-broadening (γ) and shift (δ) coefficients for 310 lines of 10 vibrational bands ν₁, ν₃, 2ν₂, ν₁+ ν₂, ν₂+ ν_3, 2ν₂ +ν₃, 2ν₁, ν₁+ ν₃, 2ν₃ and ν₁ +2ν₂ induced by argon pressure were measured with a Bruker IFS HR 125 spectrometer. The measurements were performed at room temperature, at the spectral resolution of 0.01 cm^–1 and over a wide pressure range of Ar. The calculations of the broadening coefficients γ and δ were performed in the framework of the semi-classical method. The intermolecular potential was taken as the sum of the atom–atom potential and the vibrationally and rotationally dependent isotropic induction+dispersion potential. The measured γ and δ were combined with literature data for the ν₂ and 3ν₁+ν₃, 2ν₁+2ν₂+ν₃ vibrational bands, and the optimal sets of potential parameters that gave the best agreement with the measured broadening coefficients for each vibrational band separately were found. Then, combined experimental data of 13 vibrational bands of H₂O perturbed by Ar were used to determine the analytical dependence of some potential parameters on vibrational quantum numbers.     

Recent results on K ? multinucleon absorption by FINUDA

K₂Fe₃(OH)₂(SO₄)₃(H₂O)₂ was prepared by hydrothermal synthesis. The crystal structure is the isomorphous phase of K₂Co₃(OH)₂(SO₄)₃(H₂O)₂. M?ssbauer spectra of K₂Fe₃(OH)₂(SO₄)₃(H₂O)₂ were measured at low temperatures between room temperature and 14?K, and the hyperfine interactions were analyzed. The Neel temperature is 39?K. Two paramagnetic Fe^2?+? species were observed in the M?ssbauer spectrum at room temperature, and M?ssbauer spectra measured below 38?K were decomposed into four magnetic subspectra. From the temperature dependence, it is found that the local electron density at each site is largely deviating at low temperatures, which may induce the giant coercivity.     

Synthesis and Optical Properties of SiO2-Coated CeO2 Nanoparticles

Silica (SiO₂)-coated ceria (CeO₂) nanoparticles were prepared using water-in-oil microemulsion. Polyoxyethylene (15) cetylether and cyclohexane were used as a surfactant and organic solvent. SiO₂-coated CeO₂ nanoparticles were obtained by hydrolysis of metal alkoxide (tetraethylorthosilicate, TEOS) in the solution containing CeO₂ precursor nanoparticles. The effects of CeO₂ sources (Ce metal salt) and CeO₂ particle-forming agents on the morphology of SiO₂–CeO₂ particles were investigated. Observation via transmission electron microscopy revealed that the type of particle-forming agent affected the nanoparticles' morphology and that CeO₂ nanoparticles were spherically coated with SiO₂ when using oxalic acid ((COOH)₂) as a particle-forming agent of CeO₂. Furthermore, the transmittance of the particles was high in the visible region (above 400 nm) and decreased in the ultraviolet region.     

Recent observational constraints on EoS parameters of a class of emergent Universe

New Sr-based Y-type nanocrystalline hexagonal ferrites with a nominal chemical composition of Sr ₂Mg ₂Fe ₁₂ O ₂₂ (Sr ₂Y) were prepared by autocombustion from mixtures of Sr(NO ₃) ₂, Mg(NO ₃) ₂?6H ₂O and Fe(NO ₃) ₃?9H ₂O. The newly prepared Sr ₂Y nanocrystalline particles were characterized by powder X-ray diffraction (XRD). A well crystalline phase of Sr ₂Y with hexagonal crystal structure was observed. Fourier transform infrared spectroscopy (FTIR) studies revealed the information about the positions of the ions and their bonds within the lattice structure of the Sr ₂Y. The chemical elements and their oxidation states in the Sr ₂Y hexaferrites were determined using X-ray photoelectron spectroscopy (XPS). The XRD, FTIR and XPS studies confirmed the formation of Sr ₂Mg ₂Fe ₁₂ O ₂₂ hexaferrites. The morphology and porosity of the prepared Sr ₂Y nanocrystalline Sr ₂Y hexaferrite particles were studied by field emission scanning electron microscopy. The magnetic properties of Sr ₂Y hexaferrites showed dependence on the methods of preparation conditions and calcination treatments. The values of coercivity, saturation magnetization and retentivity were in the range of 21.33–19.66 kA m ^?1, 42.44– 38.72 emu g ^?1 and 10.05–13.19 emu g ^?1 respectively.