Magnetic field induced helical structure in freestanding metal silicate tubes

Abstract

Helical structure on freestanding metal silicate membrane tubes induced by a magnetic field is reported. The phenomenon is observed for iron silicate tubes and cobalt silicate tubes grown under a horizontal field of 2.2T and a field gradient of 20.5T∕m at the room temperature in contrast to nonregular structure observed at the zero field. Direction control of helicity is achieved by changing the field gradient direction with respect to the field direction. The results are explained in terms of the magnetohydrodynamics effect on the flow of anion discharged from a metal salt solution at the growing end of the silicate tube.