Microstructure analysis of differently shaped nanocrystalline (Fe,Y)3O4

Introduction One of possibilities to tailor the physical/chemical properties of magnetite (Fe3O4) is a partial substitution of iron by 3d and 4f elements. The rare earth (4f) ions are larger than the hosts, hence they often... [ view full abstract ]

Introduction

One of possibilities to tailor the physical/chemical properties of magnetite (Fe₃O₄) is a partial substitution of iron by 3d and 4f elements. The rare earth (4f) ions are larger than the hosts, hence they often create structural distortions and have significant influence on the crystallite size, strain and morphology. The main aim of the research was to analyze effects of partial substitution of Fe³⁺ by Y³⁺ in nanocrystalline magnetite, Fe₃O₄. Possibilities for arsenic III and arsenic V removal from water by synthesized materials were tested.

Methods

Nanocrystalline Fe_3-xY_xO₄ (x=0.00, 0.05, 0.10) were prepared by use of two-stage procedure, co-precipitation at room temperature accompanied by hydrothermal treatment at 200 ^oC. Transmission electron micrographs and selected-area diffraction patterns were collected with a Jeol JEM 2100. X-ray powder diffraction data (XRPD) were collected on a PANalytical X'pert PRO MPD diffractometer.   

Results

Introducing yttrium in spinel lattice of magnetite has led to the formation of nanorods and spherical nano particles with spinel structure. Results of X-ray line broadening analysis show that addition of Y³⁺ provokes increase of apparent strain and crystallite size values in all directions. Largest average apparent crystallite size is down [110] for all compositions. With Y³⁺ concentration increase average apparent crystallite size along [110] becomes 2-3 times a larger than along [100] and [111] direction. For Fe₃O_4, the largest average strain was found in [100] direction, and the lowest in [111] direction. By TEM it was determined that the direction of growth of the spinel nanorods is down [110]. Materials characteristics toward arsenic (III) and (V) adsorption were investigated. It was found that increase of Y³⁺ concentration was followed with decrease of As (III) removal effeciency and increase in As (V) removal characteristics.

Discussion

To our best knowledge this is the first report on investigation the impact of yttrium ions on the morphology of (Fe,Y)₃O₄. The influence of partial Fe³⁺ substitution by Y³⁺ in nanocrystalline magnetite on sample morphology and on arsenic adsorption was shown. Arsenic (III) and (V) removal tests show that introducing yttrium in magnetite, with controllable synthesis procedure, can be crucial for physical/chemical properties of studied materials.