Thermal expansion behavior study of Co nanowire array with in situ x-ray diffraction and x-ray absorption fine structure techniques

Abstract

In situ x-ray diffraction and x-ray absorption fine structure techniques were used to study the structural change of ordered Co nanowire array with temperature. The results show that the Co nanowires are polycrystalline with hexagonal close packed structure without phase change up until 700 °C. A nonlinear thermal expansion behavior has been found and can be well described by a quadratic equation with the first-order thermal expansion coefficient of 4.3×10−6/°C and the second-order thermal expansion coefficient of 5.9×10−9/°C. The mechanism of this nonlinear thermal expansion behavior is discussed.

Thermal expansion behaviors of hcp and fcc Co nanowire arrays

“…In the process of the structural change from hcp to fcc, there will be a expansion along the direction of [0001] hcp which is the direction of the c-axis of Co with the hcp structure. While, for hcp Co nanowires, the pore limitation of PAAM inhibits the expansion along the direction of the c-axis [12,29]. Therefore, this kind of inhibited transformation may also enhance the axial expansion of hcp Co nanowire.…”

“…With the development of nanodevices, the study of thermal expansion properties of 1D nanomaterials has become the focus of intensive research. Up to now, some works [7][8][9][10][11][12] have been reported about the thermal expansion behaviors of metallic nanowires using in situ high-temperature x-ray diffraction (XRD). The thermal expansion behaviors Bi nanowires [9] and Ag nanowires [11] have been found to depend on their diameters.…”

Orientation-controlled synthesis and magnetism of single crystalline Co nanowires

“…The fabrication and behavior of Co nanowires have been motivated both by basic scientific interest in the magnetic properties and by their excellent application prospects for nanofunctional devices and sensors [1,12,[16][17][18][19][20]. Among the various methods developed to prepare nanowires, electrodeposition combined with anodic aluminium oxide(AAO) template method is applied widely due to its convenience, inexpensiveness and large-scale processing [4,12,16].…”

In Situ X-ray Diffraction Study on the Orientation-Dependent Thermal Expansion of Cu Nanowires

“…Recently, one-dimensional (1D) nanomaterials have attracted considerable attention because of their importance in basic scientific research and potential applications. − The thermal expansion property is one of the fundamental physical properties that is of vital importance to the nanoscale electronic and photonic structures, especially integrated circuits. There were some results about thermal expansion of nanomaterials having been reported; however, most of them focused on nanocrystals and nanoparticles, − and data on the thermal expansion properties of nanowires are still scarce. − …”