Rongzheng Liu

Multiferroic ferrite/perovskite oxide core/shell nanostructures

A general combined hydrothermal and annealing process for the fabrication of ferrite/perovskite oxide core/shell nanostructures was introduced. The coating of a perovskite oxide (ABO3) layer on spherical ferrite particles was performed in two steps. A dense and smooth amorphous layer containing B-site ions of the perovskite oxide was coated first via a controlled hydrolysis and aging process. During hydrothermal treatment and subsequent annealing process, the A-site ions were incorporated in situ into the as-coated amorphous layer preserving the spherical morphology. This synthesis of ferrite/perovskite oxide core/shell nanostructures was demonstrated in systems like Fe3O4/PbTiO3, γ-Fe2O3/PbTiO3, γ-Fe2O3/Pb(Zr,Ti)O3, CoFe2O4/BaTiO3, CoFe2O4/PbTiO3 and CoFe2O4/Pb(Zr,Ti)O3. This method allowed the shell thickness of the composite particles to be manipulated in a controlled manner with various core sizes. After the coating, the core and shell materials showed strong interactions and the ferroelectric layer dramatically affected the crystal structure, resistivity and magnetic properties of the composites.

Effective uranium(VI) sorption from alkaline media using bi-functionalized silica-coated magnetic nanoparticles

In this study, a bi-functionalized magnetic iron oxide composite which was covalently bound by ammonium and phosphonate groups has been employed as a novel sorbent for effective sorption of uranium(VI) from alkaline media. The maximum sorption capacity was observed at pH 9.0 with a capacity of 70.7 mg g−1 at CU(VI)initial = 21.7 mg L−1. The sorption isotherm followed a pseudo-second order kinetic equation and could be described by a Freundlich isotherm. The thermodynamics research showed that the sorption was a feasible and endothermic process. Since the as-prepared material could be separated by magnetic field without filtration and centrifugation, it could be a promising sorbent for highly-efficient removal of U(VI) from alkaline solution.

Uniform self-assembled magnetite chains: facile synthesis and magnetic properties

Uniform magnetic Fe3O4 chains with an average length of 20 μm built up by tens of self-assembled microspheres have been synthesized via a simple surfactant-free hydrothermal method. A possible “nucleation-growth-connection-crystallization” growth mechanism has been proposed for the formation of the Fe3O4 chains.