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The magnetic properties of α‐Fe2O3 nanoparticles of different shapes (spherical, rhombohedral and acicular), prepared as powders by a chemical route, have been investigated. The particle size effect on the Morin transition (TM = 263 K in the bulk system) have been studied by analyzing the temperature dependence of the zero‐field‐cooled (ZFC) and field‐cooled (FC) magnetization. For spherical (average diameter between 10 and 50 nm) and rhombohedral (edge between 30 and 350 nm) particles, the Morin temperature was found to decrease with decreasing particle size and increasing magnetic field. On the other hand, acicular particles (major axis between 300 and 700 nm, minor axis between 70 and 100 nm) do not show the Morin transition, unless annealed. © 1998 John Wiley & Sons, Ltd.

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2004 Superconductors Superconductors V 1500 MOCVD Growth, Micro-Structural, and Superconducting Properties of a-Axis Oriented TlBaCaCuO Thin Films. -Pure a-axis oriented Tl 2 Ba 2 Ca 1 Cu 2 O 8 superconducting thin films are deposited by a combined approach of MOCVD and Tl vapor diffusion on LaAlO3(100) buffer layers grown on SrTiO3(100) substrates. The a-axis oriented films may be used for preparing a particular type of Josephson's junctions, the so-called bi-epitaxial junctions. -(MALANDRINO, G.; PERDICARO, L. M. S.; FRAGALA*, I. L.; TESTA, A. M.; FIORANI, D.; Chem. Mater. 16 (2004) 4, 608-613; Dip. Sci. Chim., Univ. Catania, I-95125 Catania, Italy; Eng.) -W. Pewestorf 18-235