The effect of pulsed electrodeposition parameters on the microstructure and magnetic properties of the CoNi nanowires

Abstract CoNi nanowires were deposited by pulsed electrodeposition technique into porous alumina templates. The effect of off time between pulses (t off ) and reductive/oxidative time (t reduc/oxid ) on the microstructure and magnetic properties of the CoNi nanowires were investigated. Maximum coercivity and squareness were obtained for samples fabricated at t reduc/oxid = 0.5 ms and t off =400 ms. The coercivity increases in the range of 930-1990Oe by increasing of off time from 20 to 400 ms. The initially hcp structure of the nanowires was converted to an amorphous structure by increasing of off time between the pulses. JNS All rights reserved Article history

CoNi alloy nanoparticles for cancer theranostics: synthesis, physical characterization, in vitro and in vivo studies

Nanomaterials are attracting increasing interest in many biomedical fields, including the fight against cancer. In this context, we successfully synthesized CoNi alloy nanoparticles (NPs) by a simple polyol process. The magnetic characteristics of the products were measured by vibration sample magnometry, which revealed that the samples have soft ferromagnetic behavior. The microstructure and morphology were inspected by X-ray diffraction and scanning electron microscopy, respectively. Human cancer cells derived from the breast (MCF7) and oral cavity (C152) and normal cells derived from human umbilical vein endothelial cells (HUVECs) were treated with increasing concentrations of CoNi NPs, and their cytotoxic effect was measured via MTT and lactate dehydrogenase (LDH) leakage assays. We found that treatments by using 12.5 to 400 µg/mL of Co0.5Ni0.5, Co0.6Ni0.4, and Co0.4Ni0.6 NPs were associated with significant concentration-dependent toxicity toward such cell lines and profoundly enhanced LDH leakage following 48 h of exposure (P < 0.05 compared with untreated cells). Besides, a NP dose of 6.25 µg/mL did not affect the survival of HUVECs while leading to marked cell death in MCF7 and C152 cells. In vivo experiments in rats were done to investigate the biochemical and histopathological changes over three weeks, following intraperitoneal administration of Co0.5Ni0.5, Co0.6Ni0.4, and Co0.4Ni0.6 NPs (100 mg/kg). As compared with the controls, the exposure to NPs caused significant elevations in aspartate aminotransferase, alanine aminotransferase, blood urea nitrogen, serum creatinine, serum catalase activity, serum superoxide dismutase, and liver malondialdehyde levels. Also, rats treated with Co0.6Ni0.4 NPs showed more severe histopathological changes of the liver and kidney. Our findings represent an essential step toward developing theranostic nanoplatforms for selective cancer treatment

Investigations of Magnetic Properties Through Electrodeposition Current and Controlled Cu Content in Pulse Electrodeposited CoFeCu Nanowires

Abstract CoFeCu nanowires were deposited by pulsed electrodeposition technique into the porous alumina templates by a two-step mild anodization technique, using the single-bath method. The electrodeposition was performed in a constant electrolyte while Cu constant was controlled by electrodeposition current. The electrodeposition current was 3.5, 4.25, 5 and 6 mA. The effect of electrodeposition current and annealing on the magnetic behavior of the nanowires was investigated. Nanowires were fabricated with 30nm diameter and 100nm inter-pore distance with both bcc-CoFe and fccCu phases. With increasing the electrodeposition current the Cu content decrease and the coercivity and magnetization increase up to its optimum value, then decrease. Annealing improved the coercivity, maximum coercivity was obtained for sample fabricated at 5 mA current. After annealing the magnetization decrease for all sampls. The X-ray diffraction pattern of the sample at electrodeposition current 3.5 mA after annealed indicates that Cu and CoFe phases separately was formed and separate peak related to CoFeCu alloy structure is not seen

Pulse electrodeposition of Co1−xZnx nanowire arrays: Magnetic improvement through electrolyte concentration, off-time between pulses and annealing

Using different electrolyte compositions and varying the off-time between pulses, Co1xZnx nanowire arrays were fabricated by ac pulse electrodeposition. The effect of deposition parameters on alloy contents was investigated by studying the microstructures and magnetic properties of as-deposited and annealed Co1xZnx nanowires. It is shown that Zn content in CoZn nanowires exponentially increases by increasing the zinc ions in the electrolyte. The Zn content initially increases to a maximum by increase in off-time between pulses and then falls off. Adding a certain amount of Zn to Co led to form amorphous CoZn nanowires. A significant increase in magnetization, coercivity and squareness of CoZn nanowires was observed after annealing. The rate of increase in magnetization of annealed samples was seen to be inversely proportional to their initial magnetization. Improvement of magnetic properties of annealed samples may be caused by magnetic cluster formation and pinning effect

Determination of distribution function of refraction index and anion diffusion depth in porous alumina photonic crystals

  Band structure of porous alumina photonic crystal in the Γ X direction was calculated using order-N method . In a comparison of calculated results with experimental data of reflective and absorptive index, the variation of refractive index of alumina in the external region of oxide layer, around the pores were studied. A Gaussian distribution function was adopted for phosphate anions in the external oxide layer and the variation of refractive index and diffusion depth were determined. The structure of the first four bands was calculated using the obtained distribution of refractive index in the external oxide layer for both TE and TM mode. This results show a narrow full band gap in the TM mode

The effect of different oxide layers on the sensing properties of anodic alumina nanoporous film

In the present work, anodized aluminum oxide template was prepared by accelerated mild anodization technique in 0.6M phosphoric aside and 175 V, anodization voltage. Pore widening was performed by chemical etching in 0.5M phosphoric acid for 8, 16, 32, 40 minutes. Scanning Electron Microscopy (SEM) images showed the pores, diameter exponentially increases with etching time. By depositing silver contacts on the prepared samples and using an RC circuit for applying impedance spectroscopy, the characteristics of the humidity sensor based on constructed samples were investigated. The maximum response was seen for the sample etched for 40 minutes. For this sample, the detectable threshold of relative moisture was 30% and the response and the recovery time were 8, 2 seconds, respectivel

The effect of crystalline and shape anisotropy on the magnetic properties of Co and Ni nanowires

Co and Ni magnetic nanowires with different diameter and deposition time were fabricated into the alumina template using ac electrodeposition. For Ni nanowires with 30 nm diameter the coercivity initially increased then dropped with deposition time, while it only increased with deposition time for all the other diameters. In general, the results showed that the coercivity reduced with diameter. The maximum coercivity was obtained for the Co nanowire made with 30 nm diameter and 30 s deposition time and further electrodeposition time causes a reduction of the coercivity. The effect of crystal and shape anisotropy on the magnetic properties were investigated and the results revealed that the crystal anisotropy has a dominant role on the coercive field of Co nanowires, while there is a competitive effect between both the anisotropies for the Ni nanowires changing the coercivity

Magnetic properties improvement through off time between pulses and annealing in pulse electrodeposited CoZn nanowires

CoZn alloy nanowire arrays embedded in anodic aluminum oxide (AAO) template were fabricated by alternative current (ac) pulse electrodeposition. Various off times between pulses in an electrolyte with constant concentration of Co+2 and Zn+2 and acidity of 4 were employed. The effect of deposition parameters on the alloy contents, microstructures and magnetic properties of CoxZn1−x nanowires were studied. It is shown that, Co content increased by increasing the off time between pulses. This phenomenon enables us to fabricate Zn and Co-rich nanowires by adjusting the off time during the deposition procedure. Increasing the off time more than 200 ms increased the coercivity and squareness of CoZn nanowire arrays. A significantincrease in the coercivity of CoZn nanowires was observed after annealing which was varied for the samples fabricated with different electrodeposition conditions. A coercivity of 1785 Oe was obtained for the annealed sample (a sample fabricated with 50 ms off time) from initially 240 Oe