Selective self-propagating combustion synthesis of hexagonal and orthorhombic nanocrystalline yttrium iron oxide

Macroporous nariocrystalline YFeO3 was prepared by a self-propagating combustion method using yttrium nitrate and iron nitrate as precursors and glycine as a fuel. The phase structure of the product can be selectively controlled to be hexagonal or orthorhombic, by simply adjusting the ratio of glycine to nitrate. The samples were characterized by X-ray diffraction (XRD) analysis, N-2 adsorption, micro-Raman spectroscopy, Fourier transform infrared absorption spectroscopy (FT-IR), thermal analysis (TGA/DSC), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), and magnetic property analysis. Photocatalytic activity for the degradation of methylene blue in water under visible light irradiation shows that the orthorhombic YFeO3 is superior to the hexagonal form. More adsorbed oxygen and ferromagnetism of the orthorhombic sample may explain its high activity. (C) 2004 Elsevier Inc. All rights reserved.