Preparation and characterization of perovskite LaFeO3 nanocrystals

Orthorhombic structure perovskite LaFeO₃ nanocrystals with size of 59 nm were prepared by glycine combustion method. The as-prepared LaFeO₃ nanocrystals were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), high reaction transmission electron microscopy (HRTEM), energy dispersive X-ray spectrometer (EDS), scanning electron microscope (SEM), UV–Visible absorption spectroscopy, Laser Raman Spectroscopy (LRS) and Brunauer–Emmett–Teller (BET) nitrogen adsorption. The preparation process can be also applied to synthesize other complex oxides such as NdFeO₃, LaCoO₃ and LaNiO₃.     

Hydrothermal synthesis of NaEuF4 spindle-like nanocrystals

NaEuF₄ spindle-like nanocrystals have been synthesized through a simple hydrothermal method. The nanocrystals were well crystallized and exhibited fine morphology, as indicated by X-ray diffraction, transmission electron microscope and selected area electron diffractometer. The luminescence properties of these NaEuF₄ products were investigated.     

Microstructure,mechanical and wear properties of Cu–ZrO2 nanocomposites

Cu–ZrO₂ nanocomposites were produced by the thermochemical process followed by powder metallurgy technique. Microstructure development during fabrication process was investigated by X-ray diffraction, field emission scanning electron microscope and transmission electron microscope. The results show an improved distribution of zirconium dioxide (ZrO₂) nanoparticles (45?nm) in the copper matrix, which resulted in the improvement of mechanical properties of Cu–ZrO₂ composites. The nanocomposite with 9 wt-% ZrO₂ possesses the highest hardness (136.5 HV) and the superior compressive strength (413.5?MPa), resulting in an overall increase by 52 and 25%, respectively. The wear rate of the nanocomposites increased with increasing applied loads or sliding velocity.     

Rapid,simple and low-cost fabrication of BiOBr ultrathin nanocrystals with enhanced visible light photocatalytic activity

BiOBr ultrathin nanocrystals were prepared by a rapid, simple and low-cost route, and characterised by X-ray diffraction, scanning electron microscope, transmission electron microscopy, energy dispersive X-ray, UV–vis diffuse reflectance spectroscopy and electrochemical impedance spectroscopy analyses. The size of the resulting BiOBr ultrathin nanocrystals is about 60–100 nm in width and 15–20 nm in thickness. The photocatalytic activity of the samples was evaluated in terms of the degradation of RhB. Compared with BiOBr three-dimensional microspheres and P₂₅-TiO₂, the BiOBr ultrathin nanocrystals exhibited the best visible-light-induced photocatalytic activity.     

Sonochemical synthesis of amorphous long silver sulfide nanowires

Long silver sulfide nanowires have been prepared via the thioglycolic acid (TGA)-assisted sonochemical method. The transmission electron microscope (TEM) and field emission scanning electron microscope (FESEM) images reveal that the nanowires have uniform width and length. The selected area electron diffraction (SAED) pattern indicates that the Ag₂S nanowires are amorphous. Furthermore, the mechanism for the TGA-assisted sonochemical synthesis of Ag₂S nanowires has been preliminarily presented.     

Bi2S3纳米晶掺杂钠硼硅玻璃的三阶非线性光学性质

利用溶胶-凝胶方法制备了1 wt%Bi2S3纳米晶掺杂钠硼硅玻璃.利用X射线粉末衍射仪(XRD),X射线光电子能谱(XPS),透射电子显微镜(TEM),X射线能量色散谱(EDX),扫描模式透射电子显微镜(STEM)以及高分辨透射电子显微镜(HRTEM)对Bi2S3纳米晶在钠硼硅玻璃中的形貌和微结构进行了表征,同时,利用飞秒Z扫描技术在波长为770 nm对该玻璃的三阶非线性光学性能进行了分析测试.结果表明,尺寸为10～30 nm的Bi2S3正交晶系纳米晶在钠硼硅玻璃中形成,该玻璃的三阶非线性光学折射率γ、三阶非线性吸收率β和三阶非线性极化率χ(3)分别为5.90×10-16 m2/W、7.35×10-9 m/W和4.55×10-18 m2/V2.其中,该玻璃的三阶非线性极化率值比未经掺杂的钠硼硅玻璃(χ(3)=1.09×10-22 m2/V2)高出4个数量级,这表明,随着Bi2S3纳米晶的引入,该玻璃的三阶非线性光学性能将得到显著的提高.     

Te纳米线模板法加工Bi_2Te_3-Te片式棒热电材料(英文)

以碲纳米线为模板,采用简便的回流法大规模合成了Bi2Te3-Te片式棒一维材料,产量达到90%.利用X射线衍射、扫描电镜、X射线能谱、透射电镜对样品进行了分析.系统的研究了KOH、EDTA以及反应时间对产物结构的影响,提出了这种异质结构的形成机制.本制备方法可以推广到合成其它金属和半导体的一维特殊纳米结构.     

The influence of the deposition time on morphological and optical properties of Cu x S films deposited on polypropylene substrate

Copper sulfide (Cu _x S) films deposited on polypropylene substrate were obtained by chemical bath deposition (CBD) method. The influence of the deposition time on the morphology of Cu _x S films was studied by means of scanning electron microscopy. We have found that the average particles dimension increased from 37 to 49 nm with the increase of deposition time from 20 to 30 minutes. The study of optical properties of the copper sulfide films was carried out based on optical transmission spectra recorded in the 400–1000 nm wavelength range. The optical constants, such as refractive index, extinction coefficient and dielectric constant as well as electrical and optical conductivity of Cu _x S films were calculated. The obtained values are in accordance with the ones reported in the literature:We have shown that both, morphological and optical properties of Cu _x S films are strongly affected by the deposition time.     

Hydrothermal preparation, characterization and property research of flowerlike ZnO nanocrystals built up by nanoflakes

In the present paper, flowerlike ZnO nanocrystals were successfully synthesized via a simple hydrothermal route in the presence of sodium dodecyl sulfate (SDS), employing Zn(CH₃COO)₂ and KOH as the starting reactants. The phase and morphology of the product were characterized by means of powder X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and select area electron diffraction (SAED). The optical properties of the product were studied. Some factors influencing the morphology of the final product including reaction time, temperature and amounts of the surfactant were discussed. Researches showed that the flowerlike ZnO nanocrystals had a good photo-catalytic activity for degradation of safranine T under 254 nm UV light irradiation. The electrochemical research of the product showed that flowerlike ZnO nanocrystals could promote electron transfers between catechol and the Au electrode. A possible formation mechanism was also suggested based on the results of the experiments.     

A new route for the synthesis of submicron-sized LaB6

Submicron crystalline LaB₆ has been successfully synthesized by a solid-state reaction of La₂O₃ with NaBH₄ at 1200 °C. The effects of reaction temperature on the crystal structure, grain size and morphology were investigated by X-ray diffraction, scanning electron microscope and transmission electron microscope. It is found that when the reaction temperature is in the range of 1000–1100 °C, there are ultrafine nanoparticles and nanocrystals that coexist. When the reaction temperature elevated to 1200 °C, the grain morphology transformed from ultrafine nanoparticle to submicron crystals completely. High resolution transmission electron microscope images fully confirm the formation of LaB₆ cubic structure.     

Preparation of nanocrystalline Cu<Subscript>2</Subscript>O thin film by pulsed laser deposition

In this paper, the synthesis of nanocrystalline copper oxides Cu₂O and CuO thin films on glass substrates using a pulsed 532 nm Nd:YAG laser is presented. Deposition of films is achieved at two different substrate temperatures. The influence of substrate temperature on the structural and optical properties of copper oxide films are discussed and analyzed. The X-ray diffraction (XRD) results show that the deposited films are crystalline in nature. Films prepared at 300 °C substrate temperature were Cu₂O and has (111) and (200) diffracted peaks, while films grown at 500 °C were CuO and has (111) and (020) planes. The morphology of deposited films were characterized by scanning electron microscope (SEM) and atomic force microscope (AFM). The optical energy gap of Cu₂O and CuO films have been determined and found to be 2.04 and 1.35 eV respectively.     

A new colloidal precursor cooperative conversion route to nanocrystalline quaternary copper sulfide

A novel milk-like Cu-thiourea colloid has been synthesized. Nanocrystalline quaternary copper sulfide Cu₂FeSnS₄ was obtained through the Cu-thiourea colloidal precursor cooperative conversion route at low temperature. The samples were characterized by means of X-ray powder diffraction, transmission electron microscopy, scanning electron microscopy, inductively coupled plasma atomic emission spectroscopy, and X-ray energy dispersive spectroscopy techniques. The reaction details and features were described and discussed.     

Preparation and photo-induced charge transfer of the composites based on branched CdS nanocrystals and PCPDTBT

Rich branched CdS nanocrystals were synthesized by a facile hydrothermal treatment from Cd(NO₃)₂, thiourea and hexamethylenetetramine [(CH₂)₆N₄, HMT], where HMT acted as a capping agent. The morphology, structure and phase composition of CdS nanostructures were examined by X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM), and high-resolution TEM. The composites based on CdS nanocrystals and Poly[2,6-(4,4-bis-(2-ethylhexyl)-4H-cyclopenta [2,1-b:3,4-b’]dithiophene-alt-4,7-(2,1,3-benzothiadiazole)] (PCPDTBT) have been prepared by mixing of the two components in chloroform. The optical properties of the composites are investigated using ultraviolet–visible (UV–Vis) absorption and photoluminescence (PL) spectroscopies. A significant fluorescence quenching of PCPDTBT in the composites is observed at high CdS nanocrystals/PCPDTBT ratios, indicating that the photo-induced charge transfer occurred due to the energy level offset between the donor PCPDTBT and the acceptor CdS nanocrystals.     

Nanostructural palladium films for sensor applications

The composite films composed of palladium (Pd) nanocrystals and Pd-fullerenes nanocrystals obtained by physical vapor deposition (PVD) method were studied. These types of films can be applied as active material for sensor application.The films were prepared by PVD technique. They were deposited on different substrates and contained Pd in various concentrations. The structure and composition of the Pd films were studied by X-ray diffraction, scanning probe microanalysis, transmission and scanning electron microscopy. It was found that these films were composed of Pd nanocrystals placed in Pd-C₆₀ matrix.Changes of some electric properties of the film upon an influence of a toxic liquid have been characterized by DC electrical measurements. They were performed for different volatile organic compounds (VOCs). At 22 °C the electrical resistance was studied for VOC such as benzene and toluene.     

Bi2O3纳米晶玻璃三阶非线性光吸收性质的研究

利用溶胶凝胶法结合气氛控制方式合成了含Bi2O3纳米晶钠硼硅玻璃.利用X射线粉末衍射仪(XRD)、X射线光电子能谱(XPS)、透射电子显微镜(TEM)、X射线能量色散谱(EDX)、扫描模式透射电子显微镜(STEM)、高分辨透射电子显微镜(HRTEM)以及选区电子衍射(SAED)对掺杂在钠硼硅玻璃中Bi2O3纳米晶的形貌和微结构进行了表征,同时,利用飞秒开孔Z-scan技术详细地研究了Bi2O3纳米晶玻璃在800 nm处不同激发光强度下的三阶非线性光吸收性质.结果表明,在钠硼硅玻璃中形成了尺寸小于10 nm的Bi2O3单斜晶系纳米晶.随着激发光强度的增强,该玻璃的三阶非线性光吸收性质产生由饱和吸收向反饱和吸收的转变.进一步,计算得到的该玻璃三阶非线性极化率χ(3)的数量级范围在10-19~10-18m2/V2之间.这一结果说明该玻璃具有良好的非线性光学性能,并且在光限幅器等非线性光学领域具有潜在的应用价值.     

Low‐temperature synthesis of hierarchical structures of copper oxide and their superior biological activity

In this work, the authors report a facile low‐temperature wet‐chemical route to prepare morphology‐tailored hierarchical structures (HS) of copper oxide. The preparation of copper oxide collides was carried out using varying concentrations of copper acetate and a reducing agent at a constant temperature of 50°C. The prepared HS of CuO were characterised by powdered X‐rays diffraction that indicates phase pure having monoclinic structures. The morphology was further confirmed by field‐emission scanning electron microscope. It reveals a difference in shape and size of copper oxide HS by changing the concentration of reactants. In order to evaluate the effect of H₂ O₂ on CuO NPs, the prepared CuO are modified by treatment with H₂ O₂. In general trend, CuOH₂ O₂ collide showed enhanced protein kinase inhibition, antibacterial (maximum zone 16.34 mm against Staphylococcus aureus) and antifungal activities in comparison to unmodified CuO collides. These results reveal that CuO HS exhibit antimicrobial properties and can be used as a potential candidate in pharmaceutical industries.Inspec keywords: molecular biophysics, antibacterial activity, X‐ray diffraction, microorganisms, copper compounds, nanofabrication, nanoparticles, narrow band gap semiconductors, field emission scanning electron microscopy, enzymes, nanomedicine, particle size, semiconductor growthOther keywords: unmodified CuO collides, low‐temperature synthesis, morphology‐tailored hierarchical structures, copper acetate, reducing agent, monoclinic structures, copper oxide HS, CuO NPs, Staphylococcus aureus, biological activity, copper oxide, powdered X‐ray diffraction, field‐emission scanning electron microscopy, facile low‐temperature wet‐chemical method, protein kinase inhibition, antibacterial activity, antifungal activity, antimicrobial properties, pharmaceutical industries, temperature 50.0 degC, CuO     

Two-step synthesis of witherite and tuning of morphology

Compared to conventional methods, a simple route is offered for synthesis of BaCO₃ with CO₂ and least energy consumption. And the morphology of BaCO₃ was tuned by controlling reaction conditions. The X-ray diffraction (XRD), Fourier transform infrared (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and selected area electron diffraction (SAED) were employed to characterize the products, the results showed that the products with various morphologies had the same crystal phase and growth direction. However, the distinct difference of the prepared products were determined by Raman and UV-vis spectra, showing shape-dependent optical properties. The results provide a useful model system for investigating the shape-dependent optical properties of carbonate nanocrystals.     

Protrusion and whisker growth on tin coated copper substrate under stresses

Abstract

Tin thin films were coated on copper substrates using chemical method. Tin coated copper specimens under continuously applied compressive and tensile stresses were oxidised at 100°C for 8 days. Protrusion and whisker growth behaviour of tin coated copper specimens was characterised by scanning electron microscope, X-ray diffractometer and transmission electron microscope. The results show that continuously applied compressive stress on tin coated copper specimens would enhance the growth of whisker while tensile stress would reduce whisker growth. A SnO₂ layer was formed during oxidation and intermetallics of Cu₃Sn and Cu₆Sn₅ were formed between SnO₂ layer and copper substrate, which built up the residual compressive stresses in the coated tin layer. Continuously applied stress on the specimens can change the magnitude of residual compressive stress in coated tin layer, which affects the driving force for protrusion and whisker formation and growth.     

Copper(I) oxide micro-cubical structures formation by metal organic chemical vapor deposition from copper(II) acetylacetonate

The copper oxide films were deposited by decomposition of copper(II) acetylacetonate precursor in a hot wall horizontal flow tubular furnace by chemical vapor deposition method. The obtained data revealed change in phase of the deposits from crystalline copper(I) oxide (Cu₂O) to copper(II) oxide (CuO) structures on increasing the substrate temperature from 195 to 430 °C. The scanning electron microscope images showed the formation of mono-dispersed micron-sized Cu₂O cubical structures. The Cu₂O micro-cubes were observed to have a comparatively higher optical transmittance than CuO film in the visible spectral region. The Cu₂O micro-cubical films are expected to underlie the potential use as cost effective transparent conducting oxide electrode in solar cell applications.     

Single crystalline Co3O4: Synthesis and optical properties

Crystals of Co₃O₄ have been prepared from thermal decomposition of molecular precursors derived from salicylic acid and cobalt (II) acetate or chloride at 500 °C. A cubic phase Co₃O₄ micro- and nanocrystals have been obtained. The as-synthesized products were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and transmission electron microscope (TEM). The images of electron microscopes showed octahedral crystals of Co₃O₄. The volume and polarizability of the optimized structures of molecular precursors have been calculated and related to the particle size. The optical band gap of the obtained crystals has been measured. The results indicated two optical band gaps with values 2.65 and 2.95 eV for (E_g1) (E_g2), respectively.