Zn1-xCoxO纳米稀磁半导体的光催化性能

通过水热法合成了不同掺杂比例的一维Zn1-xCoxO(x=0,0.03,0.06和0.09)纳米棒,并通过X射线衍射(XRD)、高分辨透射电镜(HRTEM)、紫外可见光吸收光谱(UV-vis)和振动样品磁强计(VSM)等研究了样品的晶体结构、形貌、磁性能、光吸收性能和光催化性能。结果表明:不同掺杂比例的Zn1-xCoxO均为结晶良好的六方纤锌矿结构,Co2+以替代Zn2+的形式进入到ZnO晶格中。样品形貌为一维纳米棒状结构,分散性良好。Co掺杂ZnO使得样品的能带隙减小,可见光吸收增加。掺杂样品在室温下具有明显的铁磁性,掺杂样品能增强降解有机染料罗丹明B(RhB)的光催化活性。     

Optical properties and photocatalytic activity of Nd-doped ZnO powders

To improve the photocatalytic activity of zinc oxides, ZnO powders doped with different neodymium (Nd) concentrations were prepared via hydrothermal method. X-ray diffraction (XRD) together with X-ray photoelectron spectroscopy (XPS) patterns revealed that Nd atoms were successfully incorporated into the ZnO lattice. XRD pattern also showed some anisotropy of the powders. The photoluminescence (PL) spectrum demonstrated a strong and broad peak in the visible light region, and the intensity of visible light emission was enhanced by Nd-doping. The photocatalytic activity was evaluated by the degradation of methyl orange solution. It is shown that doping of Nd into ZnO induces an increase of the photocatalytic activity and it attains to optimum at 3% (mole fraction) doping concentration. The intense visible light emission and the enhanced photocatalytic activity were explained by the increase in electron hole pairs and induced defects like antisite oxygen O_Zn and interstitial oxygen O_i, due to the doping of Nd.     

Sol-gel derived Li-Mg co-doped ZnO films: Preparation and characterization via XRD, XPS, FESEM

Li-Mg co-doped ZnO films have been deposited onto glass substrates by sol-gel spin coating method. The structural and morphological properties of the films were characterized by X-ray diffractometer (XRD), X-ray photo-electron spectroscopy (XPS) and field emission scanning electron microscopy (FESEM). The XRD spectra indicated that the films have polycrystalline nature. The crystallite size values decreased with the increasing Mg content. The chemical composition of the Li-Mg co-doped ZnO films were confirmed by XPS. Additionally, XPS results clearly showed the existence of Mg as a doping element into ZnO crystal lattice. The surface morphology of the films was found to depend on the concentration of Mg in the ZnO:Li. The absorption band edge values of the films were calculated and these values of the films increased with increasing Mg concentration. The refractive index dispersion curves of the films obeyed the single-oscillator model. The dispersion parameters such as E_o (single-oscillator energy) and E_d (dispersive energy) of the films were determined and increase with Mg content.     

Photocatalytic activity of La-doped ZnO nanostructure materials synthesized by sonochemical method

ZnO nanostructure materials doped with different La contents were synthesized by sonochemical method. The products were characterized by X-ray diffraction(XRD), scanning electron microscopy(SEM),transmission electron microscopy(TEM), Raman spectroscopy, and Fourier transform infrared spectroscopy(FTIR). In this research, XRD patterns of pure ZnO and La-doped ZnO are specified as hexagonal wurtzite ZnO structure with no detection of La2O3 phase. SEM and TEM characterization revealed the flower shape of pure ZnO built-up from petals of hexagonal prisms with hexagonal pyramid tips. Upon doping with La, the flower-shaped ZnO is broken into individual 1D prism-like nanorods. Photocatalytic activities of the as-synthesized products were determined by measuring the degradation of methylene blue(MB) under ultraviolet–visible(UV) light irradiation.Among them, the 2.0 mol% La-doped ZnO shows better photocatalytic properties than any other products.     

载银氧化锌多孔微棒的合成与光催化性能(英文)

采用均匀沉淀法于80°C下水热2h合成棒状掺银酒石酸锌,以此为前驱体通过直接热分解制备不同含银量的多孔载银氧化锌微米棒。利用X射线衍射仪(XRD)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、紫外可见光谱(UV-VIS)和傅里叶红外光谱(FTIR)等手段对所得产物的结构和形貌进行表征,并进一步研究多孔载银氧化锌的光催化活性。结果表明:银的掺入提高了多孔氧化锌的光催化效率。掺杂量为3%(摩尔分数)的多孔氧化锌微棒的光催化效率最高,在120min内可使80%的甲基橙降解,且在太阳光下显示良好的光催化活性。     

In doped ZnO thin films

ZnO thin films were deposited by ultrasonic spray technique, zinc acetate was used as starting solution with a molarity of 0.1 M. A set of indium (In) doped ZnO (between 2 and 8 wt%) thin films were grown on glass substrate at 350 °C. The present work is focused on the influence of the doping level on the structural, optical and electrical films properties. Optical film characterization was carried by using UV-visible transmission spectroscopy, the optical gap was deduced from absorption. From X ray diffraction (XRD) analysis, we have deduced that ZnO films are formed with nanocrystalline structure with preferential (0 0 2) orientation. The grain size is increased with In doping from 28 to 37 nm. Electrical characterization was achieved using two-probes coplanar structure, the measured conductivity varies from 2.3 to 5.9 Ω cm⁻¹ when increasing the doping level. However the optical gap is reduced from 3.4 to 3.1 eV.     

Effect of fuel-to-nitrate ratio on the powder characteristics of nanosized CeO2 synthesized by mixed fuel combustion method

Synthesis of nanocrystalline ceria powders is carried out through the mixed fuel combustion approach by using different combinations of glycine and citric acid. The powders obtained with different fuel-to-nitrate (F/N) ratios are characterized by thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), X-ray diffraction (XRD), BET surface area analysis, and Raman spectroscopy. TGA and FTIR spectroscopy studies have revealed the presence of carbonaceous species and residual volatiles in the combustion synthesized ceria powders. It is observed that the variation of fuel-to-nitrate ratio has a profound influence on the carbonaceous residues from combustion, crystallite size (11-44 nm), surface area (9-39 m²/g) and morphology of the resultant powders. The Raman spectroscopy results on the variation of particle size with F/N ratio are consistent with the conclusions made from X-ray line broadening and BET surface area analysis.     

Absorption-emission study of hydrothermally grown Al:ZnO nanostructures

The preparation, structural characterization and optical properties of aluminum doped ZnO (Al:ZnO) nanostructures grown under hydrothermal method are reported. One-dimensional (1-D) growth is achieved by the controlled addition of metal nitrate as precursors in the presence of long chain surfactant, poly-ethylene glycol (PEG) at 160 °C for 20 h. The as-synthesized ZnO rods are single crystalline, exhibiting an oriented growth along [001] direction. The Al6 rod has an aspect ratio of 3.2, which can be effectively applied in optoelectronic devices. Comprehensive structural analysis using X-ray diffraction method (XRD) and Energy dispersive X-ray analysis (EDX) indicate that the dopant Al atom occupies Zn sites in ZnO and the elemental composition of Al is consistent with the amount utilized in the hydrothermal synthesis. XRD shows that the Al:ZnO nanostructures from 1 to 9 atomic percent (at.%) has hexagonal wurtzite structure of ZnO. The Al dopant effects on lattice vibration and electronic transitions of the ZnO nanostructures have been investigated by Fourier transform Infrared spectroscopy (FT-IR), Ultraviolet-visible (UV-vis) absorption spectroscopy and photoluminescence (PL) emission recorded at room temperature. The correlation existing between absorption and emission study tell that their characteristic band edge peak of doped ZnO shifts towards higher wavelength side for 3-9 at.% with respect to Al0 thus, exhibiting a red shift phenomenon with decrease in optical bandgap. The observed PL reveals two emission peaks centered at 374 nm and 530 nm. The near band edge (NBE) to defect emission ratio increases with dopant concentration indicating the linear enhancement in crystal quality and declination in zinc vacancies from 3 to 9 at.% of Al.     

Photocatalytic and Antibacterial Activities of Ag/ZnO Nanocomposities Fabricated by Co-Precipitation Method

A Ag/ZnO nanocomposite has been synthesized and characterized for investigating its photocatalytic activity.The morphology and particle size of the Ag/ZnO was studied by scanning electron microscope(SEM) and the microstructure of the as-synthesized nanocomposite was confirmed by X-ray diffraction(XRD) analysis.The elemental composition of the metal oxide was determined by energy dispersion spectrometry(EDS).Diffuse reflectance spectra(DRS),Photoluminescence(PL) spectra,and Fourier transform infrared spectroscopy(FTIR) were also studied for characterizing the nanocomposite.The average particle size was found to be around 20–30 nm.Photocatalytic activity of Ag/ZnO has been investigated over methyl violet(6B) dye under UV and visible light irradiation.The degradation of methyl violet(6B)dye using ZnO and Ag/ZnO was compared and found that Ag/ZnO composite is more efficient than ZnO.The rate of disappearance of dye was monitored spectrophotometrically in the maximum visible absorption wavelength and the extent of degradation was discussed in terms of Langmuir–Hinshelwood model.The Ag/ZnO composite was found capable of degrading the industrial dye effluent.Effect of H2O2addition on dye degradation by the Ag/ZnO was investigated and Ag/ZnO was found to be an effective antimicrobial agent.Reusability of Ag/ZnO catalyst was also tested.     

Improving color rendering index of Mn-doped ZnO nanorods on silicon-based substrate

Porous silicon pillar array(PSPA) samples which are ideal substantial materials with dominant electronic and luminescence properties were prepared by surface etching method. ZnO nanorods with or without Mn doping grown uniformly and aligned onto PSPA regardless of lattice matching show various photoluminescence(PL)properties. The doped Mn ions in ZnO nanorods were directly observed by X-ray photoelectron spectroscopy(XPS),and ZnO structures were detected by X-ray diffraction(XRD). As the doping concentration increases,XRD peaks of ZnO nanorods shift to low angle. The influences of doping Mn ions on luminescence properties of ZnO nanorods were investigated. Except for the ultraviolet(UV) PL band, the broad PL band is observed at visible region. The band could be divided into three separate bands(orange, green and red) by Lorentzian deconvolution. The intensity of orange PL band firstly increases then decreases, and then gets the maximum at the doping Mn-to-Zn molar ratio of 2.0:100.0 which is the most effective doping concentration. The green PL band is attributed to zinc vacancy of ZnO, the orange PL band to Mn ions recombination of itself, and the red PL band to oxygen vacancy of ZnO, respectively. As the Mn-doped ZnO nanorods could emit yellow green luminescence excited by UV radiation, and doped Mn ions could improve the color rendering index of the luminescence, the nanorods could be used as promising white-light emitters in the future.     

Co掺杂ZnAl2O4纳米颗粒的制备与光学性质研究

以CTAB为表面活性剂,采用水热法成功制备了不同掺杂比例的Zn1-xCoxAl2O4（x=0,0.20,0.40和0.60）纳米晶。并对样品的晶体结构、形貌、化学成分、价态和光学性能进行表征。实验结果表明,本方法所制备的不同掺杂浓度的Zn1-xCoxAl2O4纳米颗粒为尖晶石结构,晶化程度良好。根据XRD数据计算了晶胞参数a、晶格间距dhkl、晶粒尺寸D,随着掺杂Co离子浓度的增加,均表现为减小趋势。XPS能谱显示大多数Co离子占据四面体中心位置,但有少量的Co离子占据八面体中心位置。随着掺杂Co离子浓度的增加,紫外吸收光的强度逐渐增加。     

Morphology-controlled synthesis of monodisperse silver spheres via a solvothermal method

Monodisperse silver spheres were successfully synthesized by a solvothermal method with the assistance of polyvinylpyrrolidone (PVP). The final products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), laser particle size analyzer, transmission electron microscopy (TEM), Fourier transform infrared spectrophotometer (FTIR), and UV-vis absorption spectroscopy. The as-synthesized silver spheres with cubic phase structure were nearly monodisperse and had an average diameter of 250 nm. The experimental results showed that their sizes and morphologies could be tailored by changing the reaction temperature, time, and PVP concentration under solvothermal conditions. The optical properties of silver spheres were investigated as a function of PVP concentration. A possible mechanism was presented for the formation of monodisperse silver spheres.     

Characterization of zinc oxide nanoparticles synthesized by polymer assisted deposition method

Zinc oxide nanoparticles (ZNPs) are synthesized onto glass substrates by employing simple and low cost solution based modified polymer assisted deposition (PAD) method. Trionx100 is used as a capping agent and zinc acetate as the zinc source. TritonX100 concentration is varied from 0.02 to 0.45 M for the synthesis of pure ZnO NPs. TG-DTA analysis was employed to determine the decomposition temperature of TritonX100 and zinc acetate, which lead to the formation of ZnO. The films were further characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM) and high-resolution transmission electron microscope (HR-TEM), Fourier transforms infrared spectroscopy (FT-IR) and room temperature photoluminescence (PL). The results indicate that the synthesized nanoparticles (NPs) exhibits the room temperature PL with two emission peaks, one corresponding to ZnO band edge emission and the other one to point defect states created due to oxygen deficiency. The first peak undergoes blue-shift due to change in NPs size while there is no shift in the second peak. Nevertheless, with increase in TritonX100 concentration the peak intensity of defect peak decreases, indicating that the highly pure NPs have been successfully synthesized by PAD method.     

超细钴粉的制备与表征(英文)

以自制Co(OH)2为原料,乙二醇为溶剂和还原剂,十二烷基苯磺酸钠为分散剂,液相中还原制备超细钴粉。研究分散剂SDBS浓度对钴粉粒度、比表面积与磁性能的影响。利用比表面积测定、X射线衍射、傅里叶变换红外光谱、扫描电子显微镜、磁强计等测试手段对钴粉进行表征。结果表明:钴粉的比表面积随SDBS浓度的增加而增加。当分散剂用量为7.5g/L,制备的钴粉比表面积为8.1235m2/g,晶粒尺寸0.5-0.6μm。钴粉颗粒粒径比较均匀,近似球形,没有发生团聚现象,其物相呈面心立方与密排六方结构,以面心立方为主。分散剂用量为7.5g/L,制备钴粉比饱和磁化强度为39.52A·m2/kg,剩余磁化强度为3.16A·m2/kg,矫顽力为15302A/m;未加入分散剂钴粉比饱和磁化强度为132.93A·m2/kg,剩余磁化强度为21.32A·m2/kg,矫顽力为23347A/m。     

Synthesis and Characterization of the Antibacterial Activity of Zinc Oxide Nanoparticles against Salmonella typhi

Metal oxides can be used as a series of new and effective anti-bacterial agents.In this study,four concentrations of ZnO nanoparticles(0.2,0.5,0.7 and 1.0 mol/L) were synthesized using a low-temperature sol-gel method annealed at400 and 550 °C.The products were characterized by X-ray diffraction(XRD),transmission electron microscopy(TEM)and Fourier transform infrared spectroscopy(FTER).XRD results show the hexagonal wurtzite structure of the nanoparticles with the grain size in the range of 38-43 nm.TEM micrographs exhibit a polyhedral form of the synthesized nanoparticles.The antimicrobial activity of different concentrations of nanoparticles against Salmonella typhi PTCC 1609 was determined by disk diffusion and agar dilution method at five concentrations of 10,5,2.5,1.25 and 0.625 mg/mL.Analysis shows that the prepared ZnO nanoparticles have a very effective antimicrobial activity against Salmonella typhi.This activity increases by reducing the size of nanoparticles and increasing their content in the bacterial growth medium.     

The effect of substrate bias voltage on PbTe films deposited by magnetron sputtering

The PbTe films were deposited onto ITO glass substrate by radio frequency magnetron sputtering. Effect of external direct current electrical field applied between substrate and target on the quality of films was investigated. Stylus surface profile, X-ray diffraction (XRD), atomic force microscope (AFM) and Fourier transform infrared spectroscopy (FTIR) were used to characterize the films. The film thickness was measured by a conventional stylus surface profile. The crystal structure and lattice parameters of films were determined by using XRD. The surface morphology of the films was measured by AFM. The absorption coefficients and optical band gaps of films were found from FTIR. The sheet resistance of the samples was measured with a four-point probe and the resistivity of the film was calculated. All the obtained films were highly textured with a strong (2 0 0) orientation. With increasing bias voltage to −30 V, the property of crystal structure, surface morphology and absorption coefficients and resistivity were improved. However, further increase of substrate bias leads to transformation of the property.     

CVD掺硅金刚石残余应力的X射线衍射和拉曼光谱分析(英文)

采用X射线衍射(XRD)和拉曼光谱2种方法测量了不同硅碳比的CVD掺硅金刚石薄膜的残余应力。采用偏压增强热丝化学气相沉积装置在硬质合金基底上制备了掺硅金刚石薄膜,将正硅酸乙酯以不同的体积比溶解在丙酮中以使得反应气体中的硅碳比从0.1%变化到1.4%,从而控制掺硅金刚石薄膜的掺杂浓度。SEM和XRD的表征结果显示,随着硅掺杂浓度的增加,金刚石薄膜的晶粒尺寸减小,而金刚石(110)的晶面则逐渐占优。XRD法是测量入射角从0°到45°变化时对应的金刚石(220)面XRD衍射峰,并采用sin2ψ方法计算掺硅金刚石薄膜的残余应力。拉曼谱法则是通过检测金刚石特征峰偏移1332cm1位置的偏移量来测量残余应力。2种方法测得的残余应力随着硅掺杂含量的升高显示出良好的一致性,所有的硅掺杂金刚石的残余应力均为压应力,Si/C摩尔比为0.1%的薄膜具有最高的残余应力,为~1.75GPa(拉曼谱法)或~2.3GPa(XRD法)。随着硅掺杂浓度的进一步升高,薄膜的残余应力则稳定在~1.3GPa左右。     

Zn对锂电池材料LiNi_(1/3)Co_(1/3)Mn_(1/3)O_2结构和电化学性能的影响

采用共沉淀法掺入少量Zn得到Li(Ni1/3Co1/3Mn1/3)1-xZnxO2材料。通过X射线衍射、光电子能谱(XPS)和电化学测试研究掺杂对其晶体结构、元素价态和电化学行为的影响。结果表明:掺入Zn增大晶格常数;在粉末颗粒表面的Zn含量是颗粒内部的数十倍;掺杂后Co、Mn依然保持+3、+4价,但是Ni由+2、+3混合价态组成;掺入少量Zn阻止电极在4.5V电位下的不可逆氧化反应;掺入Zn有效改善高截止电压下的循环容量保持能力,其作用与改变材料表面状态有关。     

The role of pH and boron doping on the characteristics of sol gel derived ZnO films

Undoped and boron doped ZnO films (nominal volume B/Zn ratio = 1%, 3% and 5%) were deposited onto glass substrates by the sol gel method using spin coating technique. Zinc acetate dihydrate (ZnAc), 2-methoxyethanol and monoethanolamine (MEA) were used as a starting material, solvent and stabilizer, respectively. Trimethyl borate (TMB) was used as a dopant source. The pH value of the sol was adjusted with glacial acetic acid and ammonia and it changed from acid to base in nature. The effect of pH value and B dopant on the structural, morphological and optical properties of the films was investigated. The crystalline structure and orientation of the films were investigated using XRD study. The crystallite size of the films was determined. The XRD analyses showed that the undoped ZnO film crystallinity enhanced when pH of the precursor sol was increased from 5.05 to 7.00. Surface morphology was studied by a field emission scanning electron microscope (FESEM), and the effects of the doping concentration and pH values on the microstructure of the films were investigated. The optical band gap values on the surface morphology of the films were determined. The absorption edge shifted depending on the pH values and the B dopant.     

A study of structural, optical and magnetic properties of Zn0.97−xCuxCr0.03O diluted magnetic semiconductors

A set of Zn_0.97−xCu_xCr_0.03O (0 ≤ x ≤ 0.03) samples has been synthesized by the sol-gel method. The structural, optical and magnetic properties of the samples were investigated by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), photoluminescence (PL) and vibrating sample magnetometer (VSM). With Cu doping concentration increasing up to 2 at%, the XRD results showed that all diffraction peaks corresponded to wurtzite structure of ZnO, but for Zn_0.94Cu_0.03Cr_0.03O, the secondary phase of Cu emerged. PL measurements showed that Zn_0.97−xCu_xCr_0.03O powders and pure ZnO with the Cu concentration varied from 0.00 to 0.02 exhibited obvious blue shift; the green emission peak could be effectively enhanced with the increase of the Cu concentration. Magnetic measurements indicated that room-temperature ferromagnetism of Zn_0.97−xCu_xCr_0.03O was an intrinsic property when Cu concentration was less than 0.02. The saturation magnetization of Zn_0.97−xCu_xCr_0.03O (x = 0, 0.01, 0.02) increased with the increase of the Cu concentration.