Investigation on interface atomic state in compacted NiFe2O4 nanocrystalline by Mossbauer spectroscopy

In this paper, NiFe2O4 nanoparticles with average grain size of 12 nm were compacted into nanocrystalline materials under the pressure of up to 4.5 GP a. The Mossbauer spectra of NiFe2O4 nanocrystalline at room temperature sho w that the magnetic interaction and interface atomic state of nanocrystalli ne were influenced strongly by pressure. Under high pressure, the superpara magnetic relaxation of NiFe2O4 nanocrystalline were suppressed remarkably d ue to the enhancement of interparticle magnetic dipole interaction, and the degree of order of interface atoms was also improved gradually. At the sam e time, the information about the coordination polyhedron of interface atom s in NiFe2O4 nanocrystalline built under high pressure was provided by thes e Mossbauer spectra. (C) 2000 Elsevier Science S.A. All rights reserved.