The Study Of Production, Microstructure And Properties To Spiral Silver Nanobelts

The noble metal nanomaterials have been paid wide spread attention because of their unique properties in the fields of optics, electrical, biology and catalysts. In addition, spirals or helices structures are everywhere in nature and have been taken concerned in physics, chemistry, biology and other fields. This nanostructures allow special properties in photonics, electrical and other fields, as well as there are potential applications in the micro-material transport, microfluidic manipulation, remote sensing, heating and mechanical drilling.As reported in the literature, top-down fabrication approach and template methods are the two main ways to gain spiral nanostrutures. Herein, we report the phenomenon that silver spiral nanobelts could be obtained through an easy galvanic replacement reaction. Specifically, A certain length of copper nanorods were deposited onto poor conductivity such as glass slides, silicon wafer and carbon support films, and then reacted with silver nitrate and copper(II) nitrate mixture solution. Plenty of spiral silver nanostructure have been obtained. The spiral silver nanostructure was characterized by optical microscopy(OM), atomic force microscopy(AFM), scanning electron microscopy(SEM), transmission electron microscopy(TEM) and high resolution transmission electron microscopy(HRTEM). The size of spiral nanobelts of about tens of micrometers in length, 100-300 nm in width, about 40 nm in thickness, showing a shape that could be well fitted to logarithmic spiral geometry. Different sites of an individual nanobelt was analyzed by select area electron diffraction(SAED). The growth mode of the spiral silver nanobelts is determined to be of a fixed direction of according to the fcc model with defect. The optical microscope was used to observe the growth process of one spiral silver nanobelt was observed insitu and the growth looked to be complete in about 10 seconds. The spiral silver nanobelt formed with about 40 ?m in length in several seconds and the average growth rate was about 6.4 ?m/s. The current density because of electron flow through the nanobelt during the 4 seconds could be estimated to reach the 1-10 A/cm2 magnitude according to the data of nanobelt and the Faraday's law.The study have proved that the Cu(II) ions accelerated electrochemical reaction for forming spiral silver nanomaterials. The nanobelts or nanosheets were obtained respectively if decreasing or increasing the Cu(?) concentration instead. Zn(II) ions and Co(II) ions have similar but weaker effect for forming the rounded silver nanobelts, where only less than one circle spiral nanostructure could be obtained. In addition, some other metal nitrates such as Al(NO3)3, Cr(NO3)3 and Mn(NO3)2 could inhibit the formation of silver nanobelts and silver nanosheets obtained. Alkali metal and alkaline-earth metal nitrate like KNO3, NaNO3, Mg(NO3)2, Ca(NO3)2, Sr(NO3)2 had no obvious influence on the morphology of products.The strong magnetic could prevent the generation of spiral nanostructure and the centrifugal force caused the spiral to become tighter, even to came into a ring. In addition, the phenomenon triangular and hexagonal twisted by nanobelt has been observed. Herein, the article describes a simple and low cost approach and makes it possible for the design of special and complex nanostructure.In addition, when synthesize the copper nanorods, we have found a hydrothermal reaction using ascorbic acid that could gain oxalate, carbonate, copper composite productions when searching the preparation of copper precursor. Yttrium carbonate oxalate powder was synthesized by hydrothermal reaction using ascorbic acid and yttrium nitrate as reactants. The as-obtained samples were characterized by powder X-ray diffraction(XRD), infrared spectra(IR), thermal analysis(TA), and scanning electron microscopy(SEM). The morphology of the samples is about 100 micron-size powder and the as-prepared [Y(H2O)x]2(C2O4)(CO3)2 could first broken down into Y2(CO3)3 and converted into Y2O3 after annealing at 500-800?C, and thus Y2O3 powder of pure phase was obtained and characterized by XRD and SEM. The micron-size particles of LaCO3(OH) could also prepared in the same method.