Sonochemically assisted synthesis of zinc-doped maghemite

• Published in: Ultrasonics sonochemistry 2008-07, Vol.15 (5), p.791-798
• Main Authors: Drofenik, M., Kristl, M., Makovec, D., Jagličić, Z., Hanžel, D.
• Format: Article
• Language: English
• Subjects: Chemistry; Colloidal state and disperse state; Electron microscopy; Exact sciences and technology; General and physical chemistry; Magnetic measurements; Mössbauer spectroscopy; Physical and chemical studies. Granulometry. Electrokinetic phenomena; Physical chemistry of induced reactions (with radiations, particles and ultrasonics); Sonochemistry; Synthesis of magnetic nanoparticles; Ultrasonic chemistry; X-ray diffraction
• ISSN: 1350-4177; 1873-2828
• DOI: 10.1016/j.ultsonch.2007.10.002

Nanoparticles of zinc-doped maghemite were prepared using ultrasonic radiation. As a precursor, a suspension of maghemite in an alkaline aqueous solution of zinc nitrate at pH 9 was sonicated. The zinc-doped maghemite nanoparticles were investigated by X-ray diffraction, Mössbauer spectroscopy, high-resolution electron microscopy (HREM) and SQUID magnetometry. The Mössbauer measurements, which cover the temperature range 4.2K to room temperature, were acquired in zero field and an applied field of 5T. The results show that by using ultrasound radiation, zinc Zn2+ can substitute for Fe3+ up to a composition close to zinc ferrite (ZnFe2O4), which has a random distribution of Fe3+ ions over both A and B sublattices in the spinel structure with an inversity parameter of δ=0.322. This leads to a maximum saturation magnetization (Ms) of 64.1emu/g at 300K and 73.5emu/g at 2K.