title: Structural and magnetic properties of Fe and Co nanoparticles embedded in powdered Al2O3.
abstract: The structural and magnetic properties of powdered composites consisting of nanosized Fe and Co particles embedded in alumina grains have been investigated. The composites were synthesized by a novel and simple method using co-precipitation from a hybrid gel solution containing layered double hydroxide and aluminium hydroxide. After a vacuum annealing procedure, the Fe composites have a negligible number of Fe(+3) ions and a high concentration of crystalline alpha-Fe nanoparticles having truncated polyhedron shapes with an average diameter of 20 nm that are physically well separated from each other. Magnetization measurements as a function of temperature revealed a superparamagnetic-like behavior characteristic of an assembly of fine particles. A spurious ferromagnetism related to surface interaction between magnetic particles from different powder grains and the formation mechanism of the composites are also discussed.
authors: Departamento de Física, Universidade Federal do Paraná, Centro Politécnico, Curitiba, PR, Brazil.
authors: Otávio
authors: O
authors: Santini
authors: Adriano R
authors: AR
authors: de Moraes
authors: Dante H
authors: DH
authors: Mosca
authors: Paulo E N
authors: PE
authors: de Souza
authors: Adilson J A
authors: AJ
authors: de Oliveira
authors: Rafael
authors: R
authors: Marangoni
authors: Fernando
authors: F
authors: Wypych
mesh_terms: D000537:Aluminum Oxide / Q000138:chemical synthesis / Q000737:chemistry*; D003035:Cobalt / Q000737:chemistry*; D003460:Crystallization; D007501:Iron / Q000737:chemistry*; D008280:Magnetics; D053758:Nanoparticles / Q000737:chemistry*; D010316:Particle Size; D011208:Powders / Q000737:chemistry; D013499:Surface Properties; D013696:Temperature
chemical_list: D011208:Powders; D003035:Cobalt; D007501:Iron; D000537:Aluminum Oxide