Preparation and optical properties of one-dimensional magnetically oriented halloysite@Fe3O4 nanomaterials

Clay minerals with composite magnetic particles offer potential as magnetically oriented nanomaterials for application in inorganic liquid crystals. However, the instability of magnetically oriented clay@Fe3O4 materials, caused by the easy detachment of Fe3O4 particles from the clay minerals surfaces and the corrosivity of the HCl dispersant on Fe3O4 particles, has limited their development. In this work, hollow tubular halloysite (Hal) was used as the carrier for Fe3O4 particles to obtain halloysite@Fe3O4 (Hal@Fe3O4), in which Fe3O4 particles were uniformly coated on the outer surface of Hal and located in the Hal tubular lumen. In addition, LiCl was employed as a dispersant instead of HCl in Hal@Fe3O4 dispersions. They collaboratively enhanced the stability of magnetically oriented Hal@Fe3O4 nanomaterials compared to magnetically oriented palygorskite@Fe3O4 nanomaterials. The stable one-dimensional magnetically oriented Hal@Fe3O4 nanomaterials demonstrated liquid crystal properties that were adjustable by a magnetic field, and photonic crystal properties. As a result, these functional materials could be used in many fields, such as inorganic liquid crystals, photonic crystals, and photonic switches. •Halloysite was used as a carrier to prepare magnetically oriented material.•LiCl was used as a dispersant to improve the stability of halloysite@Fe3O4 dispersion.•Halloysite@Fe3O4 possessed properties of liquid crystal and photonic crystal.