Keywords : nanowires

Co-Ni Nanowires Arrays with Tunable Properties Obtained by Template Synthesis

Ruxandra Vidu; Andra Mihaela Predescu; Ecaterina Matei; Andrei Berbecaru; Cristian Pantilimon; Claudia Dragan; Mirela Sohaciu; Cristian Predescu

Advanced Materials Letters, 2020, Volume 11, Issue 6, Pages 1-5
DOI: 10.5185/amlett.2020.061524

Co-Ni nanowires arrays were obtained by electrochemical template synthesis in a polycarbonate track etched (PCTE) membrane. To diminish the effects of anomalous deposition observed in the Co-Ni system, the electrochemical deposition was performed from a solution containing nickel and cobalt in an atomic ratio of 3:1. Electrochemical deposition was performed at constant potentials E = -0.8, -0.9, -1.0, -1.1, -1.2 V vs Ag/AgCl for 15 min. The structures were characterized electrochemically via cyclic voltammetry, chronoamperometry, and charge stripping. Co-Ni nanowires were characterized by scanning electron microscopy (SEM/EDAX) to assess the morphology and the composition of the Co-Ni alloy nanowires at different deposition potentials. Electrochemical and structural analysis provided details of their deposition kinetics, structure, and morphology, which would be used to build nanowires array with controlled structure and composition.

Variation of crystallinity of Cu and Cu2O nanowires arrays grown in various pores of porous alumina membrane

Yu-Min Shen; Dipti. R. Sahu;Jow-Lay Huang; Wen-Fang Chiu; Sheng-Chang Wang; Pramoda K. Nayak

Advanced Materials Letters, 2017, Volume 8, Issue 11, Pages 1046-1051
DOI: 10.5185/amlett.2017.1493

Various pore sizes of a porous alumina membrane were fabricated using H2SO4 and H2C2O4 electrolyte under different ionization voltages. Cu nanowire arrays with high aspect ratios, uniform pore size, and ordered pore arrangement were synthesized using the above porous alumina membrane (PAM). Moreover, Cu2O nanowire arrays were prepared through the oxidization of Cu metal nanowire arrays. From the microstructure and compositional analysis, it was observed that pores of different sizes, i.e. 20~30, 70~90 and 90~100 nm could be obtained by controlling various electrolytes and anodization voltage. The Cu nanowire synthesized with various pore sizes were found to be single crystal (20~90 nm) and polycrystalline (90~100nm) respectively. The single crystal Cu with (111) direction was occurred due to homogeneous current density distribution and relationship between current density (J) and nucleus radius (ro). After oxidation of Cu, the Cu2O nanowires with the pore sizes of 20~100 nm was found to be single crystal. The rearranged of Cu and O2 lattice sites promotes the enhancement of crystalline property. 

Synthesis and growth studies of barium titanates: 0−D and 1−D nanostructures using hydrogen titanate precursor

Mohini Mishra; Raju Kumar Gupta

Advanced Materials Letters, 2017, Volume 8, Issue 10, Pages 965-970
DOI: 10.5185/amlett.2017.1566

The present work demonstrates a simple and efficient route to synthesize a variety of barium titanate (BaTiO3) nanostructures including nanowires, nanoswords, nanostars, nanocubes, and nanoparticles by a facile hydrothermal approach. The experiments showed that different morphologies can easily be tuned by varying the concentration of precursors, i.e., hydrogen titanate (H2Ti3O7) and barium hydroxide octahydrate (Ba(OH)2.8H2O), while keeping the molar ratio, reaction temperature and time fixed. The structure and morphology of BaTiO3 were characterized by field emission scanning electron microscopy (FESEM) and X-ray diffraction (XRD). The results indicate that BaTiO3 nanowires are in cubic phase with an average diameter of 80-100 nm. The shape of BaTiO3 changes from nanowires to nanoparticles with an increase in Ba(OH)2.8H2O concentration from 0.08 M to 0.51 M. Two possible mechanisms, in-situ topotactic transformation reaction and dissolution-deposition reaction have been suggested for different morphologies of BaTiO3.  The synthesized 0-D and 1-D BaTiO3 nanostructures are promising materials for many applications because of their excellent dielectric, ferroelectric and piezoelectric properties. The present work will open a new route to single reaction parameter dependent synthesis of 0- and 1-D BaTiO3 nanostructures which can find a range of applications including electronics, catalysis, energy harvesting, etc.

Pulsed-injection metal organic chemical vapour deposition for the development of copper silicate and silicide nanostructures   

Richard. O

Advanced Materials Letters, 2017, Volume 8, Issue 8, Pages 830-840
DOI: 10.5185/amlett.2017.1465

In this manuscript we report the production of copper silicate and silicide nanostructures: octahedral o-Cu(SiO3), wire w-Cu(SiO3) and wire w-Cu3Si (embedded in silicate shell) using copper bis(2,2,6,6-tetramethyl-3,5-heptanedionate) [Cu(tmhd)2] precursor and the pulsed injection metal organic chemical vapour deposition (PI-MOCVD) technique. In our experiments, particular attention has been paid to the structural composition and morphological analysis of the nanostructures which are dictated by the deposition parameters such as deposition temperature, carrier gas flow rate and injection time. Deposition processes were diffusion limited and various methods were used to show that by changing the amount of stress relaxation via the reaction time, concentration and flow rate, w-Cu(SiO3) and w-Cu3Si could be made to evolve. Nanostructures have been characterised by x-ray diffraction (XRD), Raman, scanning tunneling electron microscopy (STEM) and atomic force microscopy (AFM) techniques. It was found that the presence of oxygen (SiO2) in the silicon substrates and exposure of the nanostructures to ambient conditions results in the formation of copper silicate from initially produced copper silicide nanomaterials. This work outlines the potential for the manufacturing of various patterned copper nanostructures via PI-MOCVD. 

Synthesis Of Carbon Nanowires By SHI Irradiation Of Fullerene C70 thin Film 

R. Singhal; A. Tripathi; D. K. Avasthi

Advanced Materials Letters, 2013, Volume 4, Issue 6, Pages 413-417
DOI: 10.5185/amlett.2012.ib.105

Electrically conducting carbon nanowires, all parallel to each other and embedded in fullerene C70 matrix are created by swift heavy ion irradiation of thin fullerene C70 film at low fluences (up to 10 10 ions/cm 2 ). The conductivity of the wires is several orders of magnitude higher than the surrounding material and it is due to the transformation of fullerene into amorphous carbon within each ion hit zone. These conducting nanowires are evidenced by conducting atomic force microscopy. The typical diameter of the conducting tracks is observed to be about 11-21 nm.

Magnetoelectric Coupling In Multiferroic Ba(Fe0.01Ti0.99)O3 nanowires

Jaspreet Kaur; Jasneet Kaur; Jyoti Shah; R.K. Kotnala; Vinay Gupta; Kuldeep Chand Verma

Advanced Materials Letters, 2012, Volume 3, Issue 5, Pages 371-375
DOI: 10.5185/amlett.2012.5352

In the present work, structural, microstructural and magnetoelectric (ME) coupling of multiferroic Ba(Fe0.01Ti0.99)O3 (BFT1) nanowires have been studied. BFT1 nanowires were prepared by a hydrothermal method with reaction temperature 180 o C for 48 hours. The X-ray diffraction shows that BFT1 is polycrystalline with cubic phase. The calculated value of distortion ratio (c/a) is ~ 1. No impurity or extra phase is observed. The micrographs by transmission electron microscopy reveal nanowires like structure of BFT1with diameter lie in the range of ~ 40 - 50 nm and length greater than 1.5 μm. The ME coefficient measurement shows that the ME coupling under the effect of both ac and dc bias. It shows strong dependence on ac and dc bias applied field. The value of linear coefficient (α) called ME coefficient is calculated as ~ 16 mV/Oecm at a fixed frequency of 850 Hz. This ME coefficient α corresponds to induction of polarization by a magnetic field or of magnetization by an electric field. The observed optimum dc bias field at which the maximum magneto-electric coupling occurs is ~ 750 Oe. The magnetization hysteresis shows strong ferromagnetism.

Influence Of ZnO Buffer Layer On Growth Of Sb Doped ZnO Nano Wires Using Nano Particle Assisted Pulsed Laser Deposition (NAPLD) Using Sb As Catalyst

I.A. Palani; D. Nakamura; K. Okazaki; T. Shimogaki; M. Higashihata; T. Okada

Advanced Materials Letters, 2012, Volume 3, Issue 2, Pages 66-70
DOI: 10.5185/amlett.2012.1302

Influence of ZnO buffer layer thickness on the structural and optical properties of the Sb catalyzed/doped ZnO nanowires synthesized using NAPLD has been investigated. Buffer layer with a thickness of 100 nm, 800 nm and 1600 nm coated with Sb are used as a substrate and pure ZnO was used as a target to synthesize Sb doped ZnO nanowires. Introduction of the buffer layer lead to the growth of vertically aligned along with horizontally grown ZnO nano wires. With the increase in buffer layer thickness, the core diameter of the vertically grown ZnO nano wires was subsequently increased. Nano wires synthesized with a buffer layer thickness of 1600 nm showed a significant change in the lattice constants, resulting in measurable lower angle of about 0.06º from XRD, widening of lattice fringe spacing of 0.54 nm from TEM and Suppression of A1T and E1(L0) modes in Raman Spectroscopic. In addition a strong UV emission with absence of visible emission was observed from the room temperature PL. This confirms the generation of Sb doped ZnO nano wire with high crystal quality.