Effect of Cobalt and Nickel Doping on Structural and Magnetic Properties of Iron Oxide Nanoparticles

Two series samples of Iron Oxide nanoparticles doped with nickel and cobalt with different doping values (x?=?0.01; 0.03; 0.05 and 0.07), were successfully synthesized by using sol–gel method, and then they were characterized by X-ray diffraction, scanning electron and vibrating sample magnetometer (VSM). X-ray diffraction analysis of two series samples showed the formation α-Fe₂O₃ nanoparticles, accompanied by two phases iron spinels, CoFe₂O₄ and NiFe₂O₄. In addition, the variations in grain size were observed for both two series. The observation by scanning electron microscopy reveals a change in the morphology of the grains of all the samples doped, which confirm the cobalt and nickel effect on the morphology of iron oxide nanoparticles. Magnetic measurements which were measured by VSM showed significant magnetic parameters such as coercivity and magnetization besides the ferromagnetic behavior of both two series doped with Cobalt and Nickel.

     

锌掺杂对针状氧化铁的结构及电化学性能的影响

采用微乳–超临界干燥法制备了Zn2+掺杂针状Zn0.34Fe2.66O4纳米晶。利用红外光谱仪、能谱仪、X射线衍射仪和透射电子显微镜对样品的晶体结构、化学组成、粒径和形貌进行表征。结果表明:产物为形貌规整的针状,长径比明显小于Fe3O4的。通过循环伏安、恒流充放电和交流阻抗等方法研究了Zn0.34Fe2.66O4电极的电化学性能,结果表明:在1mol/L H2SO4溶液中,在0～1.6V(vs饱和甘汞电极)电位范围内,Zn2+掺杂Zn0.34Fe2.66O4材料的电活性和循环稳定性、可逆性优于Fe3O4的。在1A/g电流密度下,单电极比容量达1116F/g,大电流充放电性能良好。     

Effect of Supercritical Ethanol Drying on the Properties of Zinc Oxide Nanoparticles

The synthesis, characterization, and application as polymers and anti-wear additives of nanosized zinc oxide particles obtained by conventional and supercritical ethanol drying are reported in this study. The nanaoparticles of ZnO produced by the two different drying techniques were characterized using Fourier Transform Infrared (FT-IR) spectrophotometry, Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD) and Thermogravimetric analysis (TGA) to elucidate the shape, size, composition, and stability of the nanoparticles. ZnO nanoparticles were then applied to poly (vinyl chloride) (PVC) powder and light mineral oil to assess their effectiveness and suitability as additives in diverse areas. XRD analysis revealed ZnO crystalline structure with average particle size of 24.7 nm for zinc oxide nanoparticles prepared by supercritical ethanol drying while SEM showed well-isolated and monodisperse particles with average size of 61.08 nm.     

纳米ZnO的水热合成及性能研究

采用简单的水热方法制备出纯净且粒径均匀的纳米Zn O粒子,借助于X射线粉末衍射仪(XRD)和扫描电子显微镜(SEM)对其物相组成及表面形貌进行了表征,通过日光下亚甲基蓝的降解研究了其光催化性能。将获得的ZnO纳米粒子沉积成膜,经表面修饰低表面能物质1H,1H,2H,2H-全氟辛基三氯硅烷(CAS)后,采用接触角测量仪研究了其润湿性能。结果表明,反应时间为20 h的ZnO纳米粒子在日光照射20 min后,亚甲基蓝的降解率达到90%以上;经表面修饰CAS后,Zn O膜呈现良好的疏水性能;经紫外光照射后,疏水性ZnO膜转换为亲水性,实现了润湿性的转换。     

掺杂对纳米氧化锌光催化性能的影响

以纳米氧化锌为载体,采用离子掺杂的方法制得了银掺杂纳米氧化锌(Ag/ZnO)及稀土铈掺杂纳米氧化锌(Ce/ZnO)光催化剂。实验结果表明:制备的Ag/ZnO粒径在18nm左右,Ce/ZnO粒径在20nm左右,离子掺杂有效提高了纳米氧化锌的光催化性能,并且Ag/ZnO试样的效果要好于Ce/ZnO试样。     

纳米氧化铁的制备及其掺杂效应

纳米氧化铁作为气敏材料得到广泛重视。本文重点介绍了近年来应用比较普遍的合成纳米氧化铁的方法,如:溶胶—凝胶法、共沉淀法、水热法、水解法,并指出了各种方法的优缺点;同时,介绍了在掺杂了不同的物质后纳米氧化铁具有的独特的气敏性能;最后,对氧化铁基气敏元件的烧成工艺进行了比较。     

Histidine-Assisted Synthesis and Cellular Compatibility of Magnetic Cobalt Oxide Nanoparticles at Room Temperature

Magnetic nanoparticles (NPs) of cobalt oxide (Co₃O₄) with the diameter of 20–40 nm have been prepared by a simple liquid deposition method in the Histidine (His) assistance at room temperature. Ethanol plays an important role in the preparation of cobalt oxide NPs with a polycrystalline structure. The growth mechanism for Co₃O₄ cube particles has been preliminarily explained. The hysteresis loop of NPs reveals their good magnetic property indicating that they can be used in hyperthermia, cell separation etc. These applications need the magnetic particles with cytocompatible properties. The analysis of IR spectrum, TG curve and HRTEM image indicated that cobalt oxide particles was conjugated with the His molecules. Escherichia coli (E. coli) and L929 cells tests suggest a good cellular compatibility at a concentration of less than 0.25 mg/mL, indicating that the prepared Co₃O₄ NPs have a potential for several biomedical applications.     

Formation of Cobalt Ferrite Nanoparticles via Glycine-Nitrate Combustion and Their Magnetic Properties

Cobalt ferrite nanoparticles, whose degree of crystallinity and particle size depends on the molar ratio of glycine to cobalt and iron nitrates, are produced by the glycine-nitrate combustion method. The highest values of the particles’ degree of crystallinity (94%) and size (77–79 nm) are observed in samples produced at a molar ratio of 0.84 of glycine to nitrates. The values of the coercive force and residual magnetization increased, together with the glycine to nitrate ratio: at 1.12, they reached 33.8 emu/g and 1350 Oe, respectively. The saturation magnetization attained the maximal value (80 emu/g) at the molar ratio of glycine to nitrates of 0.56.     

Auto-combustion Fabrication and Optical Properties of Zinc Oxide Nanoparticles for Degradation of Reactive Red 195 and Methyl Orange Dyes

A new preparation method has been successfully utilized for the fabrication of zinc oxide nanoparticles using the auto-combustion technique and fuels (tartaric acid: TA, citric acid: CA and a mix between them) with molar ratio (Zn:TA; Zn:CA and Zn:CA:CA?=?1:1:0, 1:0:0.55 and 1:0.5:0.275). The as-fabricated zinc oxide powder (ZTA, ZCA and ZCTA samples) annealed at 500 °C. The annealed zinc oxide powder was tested by different techniques like DRS, UV–Vis, FT-IR, HR-TEM and XRD. The Crystallite size of the annealed zinc oxide was estimated to be 24, 39 and 26 nm for ZTA, ZCA and ZCTA samples, respectively. The direct band gap, lattice parameters, unit cell volume (V), the dislocation density (D) and the Zn–O bond length (L) of the prepared zinc oxide powder (ZTA, ZCA and ZCTA samples) were determined. The synthesized zinc oxide nanoparticles are used as nanocatalyst for photodegradation of reactive red 195 and methyl orange as anionic dyes utilizing UV light irradiation. The degradation of reactive red 195 dye was 91–94% after 70 min over the synthesized zinc oxide and the values of degradation increased to be 99–99.8% in 50 min with H₂O₂ under UV light irradiation. Also, the degradation of methyl orange dye was 57.55–70.57% after 300 min over the synthesized zinc oxide (ZTA, ZCA and ZCTA samples) and the values of degradation increased to be 81–95% in 70 min with H₂O₂ under UV light irradiation. Finally, the appeared rate constant (Kapp) is determined and the mechanism of the photocatalysis process is suggested for the degradation of the dyes over the synthesized zinc oxide nanoparticles.

     

掺杂对锌铁氧体吸波性能影响研究

实验采溶胶-凝胶法制备锌铁氧体前驱体,煅烧前驱体,用X射线衍射仪(XRD)、微波分光仪对煅烧后产物的物相、微波吸收性能进行研究。结果表明用溶胶-凝胶法制备了锌铁氧体;在11GHz,锌铁氧体和掺杂钴和镍的锌铁氧体的反射损耗分别为-11·55dB和-13·01dB。     

Optical Properties of Silver Halide Photochromic Glasses Doped with Cobalt Oxide

Photochromic glasses having composition (SiO₂)₄₅(B₂ O ₃)₃₅(Al₂O₃)_7.5(Na₂O)_12.5(AgBr), (Cu₂O) doped with (CoO) _x , in which, x = 0, 0.006, 0.02 and 0.07 g were prepared using the conventional melt technique. The amorphous nature of these glass samples was confirmed using X-ray diffraction analysis at room temperature. The absorption measurements in the infrared region of the spectrum were recorded in the wave number range (4000–400) cm^?1. Spectral reflectance and transmittance at normal incidence of the prepared glass samples were recorded with a spectrophotometer in the spectral range 200–2500 nm. Experimental and theoretical densities of the prepared glass samples were measured, calculated and compared. Analytical expressions were used to calculate the real and imaginary parts of the refractive indices. Dispersion parameters such as: single oscillator energy, dispersion energy, average oscillator wavelength, and Abbe’s number were deduced and compared. Absorption dispersion parameters such as: optical energy gap for direct and indirect transitions, Urbach energy and steepness parameter were calculated. Effects of doping with cobalt oxide CoO as a transition metal on linear and predicted nonlinear optical parameters were investigated and interpreted. Experimental results indicate that there is an optimum concentration of cobalt doping around 0.006 g. The optical band gap decreases with increasing doping and causes an increase in nonlinear optical parameters. Doping with cobalt oxide improves the linear and nonlinear optical properties of the prepared glasses.     

Low-Temperature Synthesis of Zinc Oxide Nanoparticles

Crystalline zinc oxide nanoparticles have been prepared by mixing aqueous solutions of zinc nitrate and hexamethylenetetramine (HMT) at 60°C and 80°C. Transmission electron microscopy and X-ray diffraction show that the ZnO nanoparticles of diameters ranging from 15–33 nm and 25–43 nm long are formed. Aspect ratio is observed to range from 1.18 to 1.74 at 60°C and 1.22 to 1.70 at 80°C as the HMT to zinc nitrate concentration ratio increases from 10 to 150. Nanoparticle size decreases as the concentration of HMT increases. Much larger ZnO particles are formed with ammonium hydroxide as a hydrolysis agent without HMT. In summary, HMT is an ammonium-hydroxide source in the reaction, a surfactant for retaining nanosize, and not necessarily a template for ZnO nucleation.     

Magnetic Properties of Nickel–Zinc Ferrite Toroids Prepared from Nanoparticles

Toroids comprised of silica-coated 10 nm diameter nickel–zinc (Ni–Fe) ferrite nanoparticles (Ni_0.5Zn_0.5Fe₂O₄) have been fabricated by careful control of both the coating process and subsequent densification by viscous sintering. A narrow processing window is identified between a maximum temperature at which the nanoparticles coarsen, losing their super-paramagnetic properties, and a lower temperature required for viscous flow densification. Key to the successful fabrication was drying and cold isostatic pressing of the silica-coated nanoparticles; other routes invariably led to cracking during either drying or sintering. The super-paramagnetic blocking temperature, the coercive field, and remanent magnetization could all be controlled over a wide range by varying the thickness of the silica coating from 1 to 15 nm. The dipole–dipole coupling distance is estimated to be 4 nm. The high-frequency (1–500 MHz) properties were sensitive to the sintering temperature as well as the thickness of the silica coating. Toroids sintered at 1000°C or less exhibited no high-frequency magnetic losses and their permeability decreased with increasing temperature, suggesting that the permeability was controlled by thermally activated magnetization relaxation.     

The Effect of Iron Oxide Magnetic Nanoparticles on Smooth Muscle Cells

Recently, magnetic nanoparticles of iron oxide (Fe₃O₄, γ-Fe₂O₃) have shown an increasing number of applications in the field of biomedicine, but some questions have been raised about the potential impact of these nanoparticles on the environment and human health. In this work, the three types of magnetic nanoparticles (DMSA-Fe₂O₃, APTS-Fe₂O₃, and GLU-Fe₂O₃) with the same crystal structure, magnetic properties, and size distribution was designed, prepared, and characterized by transmission electronic microscopy, powder X-ray diffraction, zeta potential analyzer, vibrating sample magnetometer, and Fourier transform Infrared spectroscopy. Then, we have investigated the effect of the three types of magnetic nanoparticles (DMSA-Fe₂O₃, APTS-Fe₂O₃, and GLU-Fe₂O₃) on smooth muscle cells (SMCs). Cellular uptake of nanoparticles by SMC displays the dose, the incubation time and surface property dependent patterns. Through the thin section TEM images, we observe that DMSA-Fe₂O₃ is incorporated into the lysosome of SMCs. The magnetic nanoparticles have no inflammation impact, but decrease the viability of SMCs. The other questions about metabolism and other impacts will be the next subject of further studies. Song Zhang and Xiangjian Chen contributed equally to this work.     

湿法氧化锌对天然橡胶性能的影响

研究湿法氧化锌FF和HR对天然橡胶(NR)性能的影响,并与普通氧化锌(间接法)对比。结果表明:与普通氧化锌相比,湿法氧化锌FF和HR的活化和补强作用显著,添加湿法氧化锌FF和HR会缩短NR胶料的焦烧时间和t90,增大Fmax;在氧化锌用量相同时,3种氧化锌的NR硫化胶的拉伸强度由大到小的顺序为湿法氧化锌FF、湿法氧化锌HR和普通氧化锌,定伸应力由大到小的顺序为湿法氧化锌HR、湿法氧化锌FF和普通氧化锌,拉断伸长率由大到小的顺序与定伸应力相反;添加普通氧化锌的NR胶料的Payne效应较弱;氧化锌用量增大时,3种氧化锌的NR硫化胶的储能模量增大,损耗因子减小。     

氧化锌与活性氧化锌对汽车发动机悬置胶料及成品性能的影响

研究氧化锌与活性氧化锌对汽车发动机悬置胶料及成品性能的影响。结果表明:与氧化锌胶料相比,等量活性氧化锌胶料的t_10和t_90缩短,抗硫化返原性能提高,定伸应力和拉伸强度降低,拉断伸长率和压缩永久变形增大,撕裂强度和耐热老化性能提高;随着活性氧化锌用量减小,活性氧化锌胶料的交联密度、抗硫化返原性能和物理性能降低;与采用氧化锌胶料的发动机悬置相比,采用活性氧化锌胶料的发动机悬置生产效率较高,减震性能稍差,高温耐久性能相当。