Magnetic properties of Co-impregnated zeolites

TitleMagnetic properties of Co-impregnated zeolites
Publication TypeJournal Article
Year of Publication2009
AuthorsBercoff PG, Bertorello HR, Saux C, Pierella LB, Botta PM, Kanazawa T, Zhang Y
Journal TitleJournal of Magnetism and Magnetic Materials
Volume321
Pages3813-3820
Date Published11/01
ISBN Number0304-8853
Accession NumberISI:000269720200030
Keywordsco-zeolite, co-zsm-5, cobalt, cubic co, magnetic property, molecular-sieves, nanomagnetism, particles, relaxation, selective reduction, wet impregnation
Abstract

The structure and magnetic properties of Co-containing zeolites prepared by wet impregnation were investigated. The samples were calcined and then reduced in flowing H-2. The samples studied have large saturation magnetization due to the presence of cubic Co particles over a wide range of sizes. The zero field cooling-field cooling curves show a sharp magnetization peak with a blocking temperature around 7 K followed by an exponential decay and two other peaks - of much lower amplitude - around 160 and 280 K. The low temperature peak is analyzed considering first, at T-crit, thermal relaxation toward equilibrium over an energy barrier, with increasing viscosity S with T. Above T-crit relaxation does not occur and viscosity abruptly goes to zero. The behavior of the smallest Co particles is unusual above the blocking temperature. (C) 2009 Elsevier B.V. All rights reserved.

URL<Go to ISI>://000269720200030
DOI10.1016/J.Jmmm.2009.07.046