A new 2212-type stair like structure: Bi14Sr21Fe12O61, m=5 member of the generic [Bi2Sr3Fe2O9]m[Bi4Sr6Fe2O16] family

A new oxide, Bi₁₄Sr₂₁Fe₁₂O_61, with a layered structure derived from the 2212 modulated type structure Bi₂Sr₃Fe₂O₉, was isolated. It crystallizes in the I2 space group, with the following parameters: a=16.58(3) Å, b=5.496(1) Å, c=35.27(2) Å and β=90.62°. The single crystal X-ray structure determination, coupled with electron microscopy, shows that this ferrite is the m=5 member of the [Bi₂Sr₃Fe₂O₉]_m[Bi₄Sr₆Fe₂O₁₆] collapsed family. This new collapsed structure can be described as slices of 2212 structure of five bismuth polyhedra thick along , shifted with respect to each other and interconnected by means of [Bi₄Sr₆Fe₂O₁₆] slices. The latter are the place of numerous defects like iron or strontium for bismuth substitution; they can be correlated to intergrowth defects with other members of the family.     

Surface modification of thermoplastics by atomic layer deposition of Al2O3 and TiO2 thin films

Al₂O₃ and TiO₂ thin films were deposited by atomic layer deposition at 80-250 °C on various polymeric substrates such as polymethylmethacrylate (PMMA), polyetheretherketone (PEEK), polytetrafluoroethylene (PTFE) and ethylenetetrafluoroethylene (ETFE). The films were studied with FESEM, EDX, XRD, contact angle measurements and adhesion tests. The film growth rates on the thermoplastics were close to the corresponding growth rates on Si substrates. The adhesion of the films was good on PEEK and poor on PTFE. All coated surfaces showed lower water contact angles than the uncoated thermoplastics. Furthermore, the water contact angles on all TiO₂-coated surfaces decreased upon UV illumination, most efficiently with crystalline TiO₂ coatings.     

不同晶型Bi2O3可见光光催化降解罗丹明B的研究

采用化学沉淀法制备了α、β、γ 3种晶体结构的Bi₂O₃光催化剂。利用XRD、TEM、氮气吸附、TG-DSC、紫外-可见漫反射光谱对样品的晶体结构、微观形貌、光学吸收特性进行了表征,并以罗丹明B(RhB)作为模型污染物,研究了不同的粉体光催化剂在可见光(λ>420 nm)照射下的光催化能力。结果表明：制备的α-Bi₂O₃为长3 μm、宽1 μm的板条状颗粒,带隙为2.84 eV;β-Bi₂O₃为粒径约150 nm的不规则颗粒,带隙为2.75 eV;γ-Bi₂O₃为直径6 nm、长度150~200 nm的纳米管,带隙为2.68 eV。在可见光照射下Bi₂O₃光催化降解RhB的活性如下：γ-Bi₂O₃>β-Bi₂O₃>α-Bi₂O₃,其中γ-Bi₂O₃在辐照60 min后对罗丹明B的脱色率可达97%以上。     

浸渍-分解法制备高可见光催化活性的Bi2O3/TiO2纳米管阵列

用浸渍-分解法将Bi₂O₃纳米颗粒沉积在TiO₂纳米管壁上, 制备了Bi₂O₃/TiO₂纳米管阵列. 用电感耦合等离子体发射光谱(ICP-AES)测定了Bi₂O₃/TiO₂ 纳米管阵列的化学组分, 利用X 射线衍射(XRD)、扫描电镜(SEM)、透射电镜(TEM)和紫外-可见(UV-Vis)吸收光谱表征了所制备的样品. 通过在可见光下(λ>400 nm)降解甲基橙(MO)水溶液来评价样品的光催化活性. 结果表明, Bi₂O₃纳米颗粒均匀地沉积在TiO₂纳米管中. Bi₂O₃/TiO₂纳米管阵列具有比纯Bi₂O₃膜和N-TiO₂纳米管阵列高得多的可见光催化活性. Bi₂O₃/TiO₂纳米管阵列活性的增强是其强可见光吸收和Bi₂O₃与TiO₂之间形成的异质结的协同作用的结果.     

Structural and electrical properties of the 2Bi2O3·3ZrO2 system

Powder mixtures of α-Bi₂O₃ (bismite) and monoclinic m-ZrO₂ (baddeleyite) in the molar ratio 2:3 were mechanochemically and thermally treated with the goal to examine the phases, which may appear during such procedures. The prepared samples were characterized by X-ray powder diffraction, differential scanning calorimetry (DSC), electrical measurements, as well as scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The mechanochemical reaction leads to the gradual formation of a nanocrystalline phase, which resembles δ-Bi₂O₃, a high-temperature Bi₂O₃ polymorph. Isothermal sintering in air at a temperature of 820 °C for 24 h followed by quenching to room temperature yielded a mixture of ZrO₂-stabilized β-Bi₂O₃ and m-ZrO₂ phases, whereas in slowly cooled products, the complete separation of the initial α-Bi₂O₃ and m-ZrO₂ constituents was observed. The dielectric permittivity of the sintered samples significantly depended on the temperature. The sintered and quenched samples exhibited a hysteresis dependence of the dielectric shift, showing that the ZrO₂-doped β-Bi₂O₃ phase possess ferroelectric properties, which were detected for the first time. This fact, together with Rietveld refinement of the β-Bi₂O₃/m-ZrO₂ mixture based on neutron powder diffraction data showed that ZrO₂-doped β-Bi₂O₃ has a non-centrosymmetric structure with as the true space group. The ZrO₂ content in the doped β-Bi₂O₃ and the crystal chemical reasons for the stabilization of the β-Bi₂O₃ phase by the addition of m-ZrO₂ are discussed.     

四角星形BiVO4/Bi2O3催化剂的制备及性能

采用水热法合成具有四角星形貌的钒酸铋,再将钒酸铋浸渍在碱溶液里二次水热,制备出BiVO_4/Bi_2O_3催化剂。采用X射线粉末衍射(XRD)、扫描电子显微镜(SEM),紫外-可见漫反射(UV-Vis DRS)等方法对样品进行表征。可见光下,BiVO_4/Bi_2O_3复合物的光催化降解罗丹明B性能及光电流响应均优于纯BiVO_4。这是由于BiVO_4/Bi_2O_3复合材料形成了异质结构,有效抑制了光生电子与空穴的复合效率。     

四角星形BiVO4/Bi2O3催化剂的制备及性能研究

采用水热法合成具有四角星形貌的钒酸铋,再将钒酸铋浸渍在碱溶液里二次水热,制备出BiVO₄/Bi₂O₃催化剂。采用X射线粉末衍射(XRD)、扫描电子显微镜(SEM),紫外-射(UV-Vis DRS)等方法征。可见光下,BiVO₄/Bi₂O₃复合物的光催化降解丹明B性能及光电优于纯BiVO₄。BiVO₄/Bi₂O₃复合材料形成了异质结构,有效抑制了光电子与空穴的复合效率。     

微波水热辅助电沉积法制备Bi_2S_3薄膜

采用微波水热辅助电沉积法在ITO导电玻璃表面制备了形貌均匀具有纳米棒、纳米板状结构的Bi2S3薄膜。利用XRD、XPS、场发射扫描显微镜(FESEM)、TEM和UV-Vis-NearIR对薄膜的结构、形貌、光学性能进行了表征。结果显示微波水热辅助电沉积法制备的Bi2S3薄膜具有良好的结晶性能;随着微波水热温度的提高,所制备Bi2S3薄膜的结晶性能先增强后降低,合适的温度是130℃。与电沉积法制得薄膜相比,采用微波水热辅助电沉积法制得Bi2S3薄膜的禁带宽度由1.44eV增加到1.84eV。     

g-C3N4/Bi2O2CO32D纳米片复合材料的制备及可见光催化性能研究

采用自组装和化学沉淀法分别制得两种可见光驱动复合材料石墨相氮化碳/碳酸氧铋(g-C_3N_4/Bi_2O_2CO_3).采用X射线衍射光谱(XRD),紫外可见光谱、扫描电镜(SEM)、N_2吸附、电化学阻抗谱(EIS)和X射线光电子能谱(XPS)等分析手段对制备的催化剂进行了表征.结果表明,制备方法对纳米复合材料的晶相、形态及光学性能没有影响,但是影响g-C_3N_4和Bi_2O_2CO_3之间的相互作用力,导致光生电子-空穴对的分离速率存在显著差异.以可见光驱动苯酚和罗丹明B的降解实验为探针反应检测催化剂的光催化性能.实验结果表明自组装法得到的异质结催化剂中相互作用力更强,催化效果最高.O_2-是罗丹明B降解反应的主要活性物种,染料的光敏化、Bi_2O_2CO_3与g-C_3N_4综合效应,导致光生载流子电荷分离效率更高.     

Bi2O3掺杂对Ag(Nb0.8Ta0.2)O3陶瓷结构和介电性能的影响

本文研究了Bi₂O₃掺杂对Ag(Nb_0.8Ta_0.2)O₃陶瓷的结构和介电性能的影响。X射线衍射(XRD)结果表明,Bi₂O₃的掺杂可以使陶瓷中Ag⁺被还原并析出,且银析出的量随Bi₂O₃掺杂量的增加而不断增加,这可能源自于Bi³⁺对Ag⁺的取代。在一定范围内增大Bi₂O₃掺杂量可提高Ag(Nb_0.8Ta_0.2)O₃陶瓷的室温介电常数,降低介电损耗,并使温度系数向负值方向移动。当Bi₂O₃的掺杂量约为3.5wt%时,样品具有较大的介电常数(ε=672)和较小的介电损耗(tanδ=7.3×10^-4)。     

Microwave effects on the oxidative coupling of methane over Bi2O3-WO3 oxygen ion conductive oxides

The oxidative coupling of methane over (Bi₂O₃)_1-x(WO₃)_x (x=0.2, 0.3, 0.4) oxygen ion conductive oxide catalysts irradiated by microwave has been studied. Compared with a conventional heating mode, the temperature of the catalytic bed is much lower with microwave irradiation and there is a change in selectivity favoring the production of C₂ products.     

Bi_2O_3掺杂对Ag(Nb_(0.8)Ta_(0.2))O_3陶瓷结构和介电性能的影响(英文)

本文研究了Bi2O3掺杂对Ag(Nb0.8Ta0.2)O3陶瓷的结构和介电性能的影响。X射线衍射(XRD)结果表明,Bi2O3的掺杂可以使陶瓷中Ag+被还原并析出,且银析出的量随Bi2O3掺杂量的增加而不断增加,这可能源自于Bi3+对Ag+的取代。在一定范围内增大Bi2O3掺杂量可提高Ag(Nb0.8Ta0.2)O3陶瓷的室温介电常数,降低介电损耗,并使温度系数向负值方向移动。当Bi2O3的掺杂量约为3.5wt%时,样品具有较大的介电常数(ε=672)和较小的介电损耗(tanδ=7.3×10-4)。     

Selective hydrothermal synthesis of BiOBr microflowers and Bi2O3 shuttles with concave surfaces

Through controlling the amount of NaOH added, BiOBr and Bi₂O₃ with different shapes were hydrothermally synthesized in the reaction system of Bi(NO₃)₃-hexadecyl trimethyl ammonium bromide (CTAB)-NaOH. As 8 mmol of NaOH was added, BiOBr microflowers constructed of nanoflakes were synthesized. The thickness of these single-crystal nanoflakes was about 20 nm. In the similar condition, when the amount of NaOH added was 28 mmol, Bi₂O₃ shuttles with concave surfaces were obtained. The length of these shuttles was 100 μm and the diameter at the middle of these shuttles was 50 μm. The photocatalytic activity of as-prepared BiOBr microflowers was evaluated by the degradation of methyl orange (MO) under visible-light irradiation (λ>420 nm), which was up to 96% within 90 min.     

溶剂热法制备Bi2S3纳米材料

0引言纳米材料具有特殊的结构和性能,可广泛应用于化学、物理学、电子学、光学、机械和生物医药学等领域[1￣5]。其中一维或准一维纳米结构体系或纳米材料的研究既是研究其它低维材料的基础,又与纳米电子器件及微型传感器密切相关,是近年来国内外研究的前沿[6￣9]。近年来,人们虽然做了许多尝试来制备一维纳米结构材料,但合成这类材料特别是合成半导体一维纳米材料仍然是一个巨大的挑战。随着维数的减小,半导体材料的电子能态发生变化,其光、电、声、磁等方面性能与常规体材料相比有着显著的不同[10￣12]。Bi2S3是一种重要的半导体材料,受…     

Template synthesis of heterostructured polyaniline/Bi2Te3 nanowires

Heterostructured polyaniline/Bi₂Te₃ nanowires have been prepared by chemical and electrochemical reactions on a porous alumina template. Its morphology and structure have been studied by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and electron probe microanalysis. The microscope analysis reveals that Bi₂Te₃ is well enveloped in polyaniline tubules in pores of alumina template. This microscopic material shows possible application in microthermoelectric device.     

Preparation and photocatalytic activity of Sb2S3/Bi2S3 doped TiO2 from complex precursor via gel-hydrothermal treatment

Sb₂S₃/Bi₂S₃ doped TiO₂ were prepared with the coordination compounds [M(S₂CNEt)₃] (M=Sb, Bi; S₂CNEt=pyrrolidinedithiocarbamate) as precursors via gel-hydrothermal techniques. The doped TiO₂ were characterized by XRD, SEM, XPS and UV-vis diffuse reflectance means. The photocatalyst based on doped TiO₂ for photodecolorization of 4-nitrophenol (4-NP) was examined. The optimal Bi₂S₃/Sb₂S₃ content, pH and different doped techniques have been investigated. Photocatalytic tests reveal that M₂S₃ doped TiO₂ via the gel-hydrothermal route performs better photocatalytic activity for photodegradation reaction of 4-nitrophenol (4-NP).     

Bi2WO6 photocatalytic films fabricated by layer-by-layer technique from Bi2WO6 nanoplates and its spectral selectivity

Bi₂WO₆ multilayer films have been fabricated successfully by a layer-by-layer (LbL) technique from Bi₂WO₆ nanoplates, which show higher visible-light photoactivity (λ>420 nm) than that of Bi₂WO₆ nanoplate powders and P25 TiO₂ films. The films were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), and UV-visible absorption spectroscopy. Photocatalytic activities of the films were evaluated by the rhodamine B (RhB) decomposition under UV and visible-light irradiation. Thickness and photoactivity of the film can be modified easily by changing the deposition cycles. Bi₂WO₆ films have the spectral selectivity of the photocatalytic degradation of RhB. Under the wavelength greater than 300 nm, the RhB molecules tend to be transformed to rhodamine over Bi₂WO₆ films selectively. However, in the case of shorter wavelength (λ=254 nm) light irradiation, the RhB molecules can be photodegraded completely.     

三维有序大孔复合材料Bi2O3/TiO2制备与多模式下光催化降解结晶紫

以TiO2为基体,在聚苯乙烯(PS)胶球和EO20PO70EO20(P123)两种模板剂作用下通过溶胶-凝胶及煅烧后处理方法制备了三维有序大孔纳米复合材料Bi2O3/TiO2.经傅里叶变换红外(FT-IR)光谱、X-射线衍射(XRD)、等离子体原子发射光谱(ICP-AES)、紫外-可见漫反射吸收光谱(UV-Vis DRS)、X-射线光电子能谱(XPS)、扫描电子显微镜(SEM)和N2吸附-脱附等物理测试手段对其组成、结构、形貌及表面物理化学性能进行了表征.结果表明,该复合材料晶型结构良好,孔结构排列整齐有序,孔壁呈介孔结构,属于三维有序大孔材料(3DOM).与TiO2相比,3DOM-Bi2O3/TiO2对光的吸收至少红移60 nm,且红移至可见区.在紫外光、可见光以及微波辅助等多模式光催化降解结晶紫的实验中,复合材料3DOM-Bi2O3/TiO2表现出良好的光催化活性,其活性明显高于P25、Bi2O3和Bi2O3/TiO2.同时,该复合材料针对不同类型的染料均表现出较好的紫外光降解效果,且3次循环实验后,依旧保持较高活性.     

PO43-掺杂Bi2O2CO3/Bi0的制备及其可见光催化性能

构建氧空位以及附着金属单质Bi(Bi⁰)是增强半导体材料光吸收性能、促进半导体光生载流子分离的有效方法。通过简单的共沉淀法及氢气热还原成功制备了PO₄^3-掺杂Bi₂O₂CO₃附着Bi⁰(Bi-P-BOC)的可见光催化剂,并对其在可见光下催化降解氧氟沙星(OFX)的性能及机理进行了研究。材料表征结果表明BOC随着PO₄^3-的均匀掺杂,可见光吸收能力增强,表面缺陷增多,比表面积增大。而随着氢气热还原,BOC表面形成Bi⁰的同时也原位构建了大量的氧空位。可见光催化性能测试表明,Bi-P-BOC可以在180 min内降解约85%的OFX,降解速率为0.013 0 min^-1,是BOC降解速率的8倍。Bi-P-BOC光催化降解机理表明其具有更好的可见光吸收能力,Bi⁰以及氧空位的存在促进了光生载流子的分离,h⁺是其...     

PO43-掺杂Bi2O2CO3/Bi0的制备及其可见光催化性能

构建氧空位以及附着金属单质Bi(Bi⁰)是增强半导体材料光吸收性能、促进半导体光生载流子分离的有效方法。通过简单的共沉淀法及氢气热还原成功制备了PO₄^3-掺杂Bi₂O₂CO₃附着Bi⁰(Bi-P-BOC)的可见光催化剂,并对其在可见光下催化降解氧氟沙星(OFX)的性能及机理进行了研究。材料表征结果表明BOC随着PO₄^3-的均匀掺杂,可见光吸收能力增强,表面缺陷增多,比表面积增大。而随着氢气热还原,BOC表面形成 Bi⁰的同时也原位构建了大量的氧空位。可见光催化性能测试表明,Bi-P-BOC可以在180 min内降解约85%的OFX,降解速率为0.013 0 min^-1,是BOC降解速率的8倍。Bi-P-BOC光催化降解机理表明其具有更好的可见光吸收能力,Bi⁰以及氧空位的存在促进了光生载流子的分离,h+是其光催化降解过程中的主要的活性氧物种(ROS),此外,¹O₂和·O₂^-也对降解有一定贡献。