Structural and Magnetic Characterization of Nickle Nanoporous Sturctures
Bingqing Li 1, Xuzhao Chai 2, Yaowu Hao 2, X. M. Cheng 1
1. Department of Physics, Bryn Mawr College
2. Department of Materials Science and Engineering, University of Texas at Arlington
Abstract:
Nanoporous structures have been increasingly intensively investigated in recent years.
Those nanoporous-structured materials, with high surface-to-volume ratios, possess
unique magnetic properties, which results in potential applications in sensors and
energy storage. In this work, the magnetic interactions and the magnetic reverals of
templated nickel nanoporous structures are studied. Samples are fabricated with
colloid solution of self-assembled monodispersed polystyrene spheres with two
different diameters, 550 nm and 750 nm on gold-coated silicon wafers. The charge
density controlled electrochemical deposition of Ni into the polystyrene template
produces three-dimensional Ni nanoporous structures with different thicknesses. Both
scanning electron microscope (SEM) and atomic force microscope (AFM) are used to
measure the structural properties of templated Ni nanoporous samples, including the
pore size, the thickness and the uniformity. The X-ray diffraction (XRD) analysis is
incorporated to confirm the deposition of nickel and the thickness of the deposition.
The hysteresis loop and the first-order reversal curves (FORCs) of samples are
measured and studied with the vibrating sample magnetometer (VSM) to investigate
the magnetic interaction and the coercivity of magnetic networks in the nanoporous
Ni. The comparison among the magnetization and coercivity of the different Ni
nanoporous structures and those of Ni nano thin films can reveal the dependence of
the magnetic properties of nickel on the structural properties such as thickness, pore
size and uniformity in nanoscale.