Fabrication and uniform alignment of nickel-coated diatomite flakes by rotating magnetic fields

Coscinodiscus diatomite was used as a template to fabricate uniform flaky magnetic particles by means of electroless nickel deposition. The morphology, coating composition, and magnetic properties of the prepared nickel-coated Coscinodiscus diatomite (magnetic microdisks) were characterized in detail using scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), X-ray diffraction (XRD), and vibrating sample magnetometer (VSM). The results indicated the successful deposition of a uniform and compact nickel coating on the template, with flaky magnetic particles of good surface quality. A rotating magnetic field generated by a Helmholtz coil system was used to align the magnetic microdisks dispersed in PDMS. The results showed that the magnetic microdisks could be driven to align parallelly with the plane of the rotating magnetic field, and a highly ordered alignment was achieved due to the time-varying magnetic torque.