Synthesis and magnetic properties of haematite with different particle morphologies

• Published in: Journal of alloys and compounds Vol. 280; no. 1-2; pp. 273 - 278
• Main Authors: Sorescu, M, Brand, R.A, Mihaila-Tarabasanu, D, Diamandescu, L
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 23.10.1998; Elsevier
• Subjects: Chemical synthesis; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Exact sciences and technology; Fine-particle systems; Magnetic materials; Magnetic properties; Magnetic properties and materials; Mössbauer spectroscopy; Oxides; Physics; Small particles and nanoscale materials; Studies of specific magnetic materials; Oxides; Magnetic materials; Chemical synthesis; Mössbauer spectroscopy; Magnetic properties; Antiferromagnetism; Hematite; Hyperfine magnetic field; Weak ferromagnetism; Fine particle; Preparation; Magnetic structure; Experimental study; Iron oxides; Microstructure
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/S0925-8388(98)00719-1

Haematite particles of four different morphologies (polyhedral, platelike, needlelike and diskshape) were synthesized by the hydrothermal method. The morphology and average particle diameter (1.4; 7.4; 0.2 and 0.12 μm, respectively) were determined by transmission electron microscopy (TEM) combined with electron diffraction. The haematite samples were studied by transmission Mössbauer spectroscopy in the temperature range 4.2–300 K. In all cases, a weak ferromagnetic phase (WF) was present above the Morin temperature of 230 K and found to coexist with an antiferromagnetic phase (AF) below this temperature. However, the populations of the two phases at 230 K were demonstrated to depend on the morphology of the particles. Moreover, the WF and AF phases exhibit a different dependence of the magnetic texture on temperature and particle morphology.