Magnetic properties of partially-inverted zinc ferrite aerogel powders

Abstract

Fine powders of ZnFe2O4 with an average particle size of 10 nm and inversion parameter of 0.21 were synthesized by the aerogel procedure. Portions of the powders were calcined in air at 500 and 800 degrees C and other portions were ball-milled for 10 h. The materials were characterized by x-ray diffractometry, vibrating sample, and SQUID magnetometry, Mossbauer spectrometry, and low temperature calorimetry. Upon calcination the powders underwent significant changes in grain size, inversion parameter; and hence magnetic properties. The magnetic state of the as-produced and calcined samples is best described as disordered and highly dependent on temperature. Upon ball-milling the grain size varied widely and the inversion parameter attained a value of 0.55. The magnetic properties of the ball-milled sample are similar to those of ferrimagnetic MgFe2O4 powders having comparable grain size and inversion parameters. (C) 1997 American Institute of Physics

Structure of manganese zinc ferrite spinel nanoparticles prepared with co-precipitation in reversed microemulsions

“…Using neutron powder diffraction, the degree of inversion X for ZnFe 2 O 4 nanoparticles prepared by co-precipitation was determined to increase with decreasing particle size from 0.108 at particle size 9.6 nm to 0.142 at particle size 2.9 nm (Kamiyama et al 1992). Besides on the particle size, the degree of inversion depends also on the preparation method (Hamdeh et al 1997;Ammar et al 2004). A higher degree of inversion in nanoparticles than in the bulk material was also detected in MnFe 2 O 4 (Chen et al 1996;Carpenter et al 1999) and in mixed MnZn ferrites (Fetami et al 1998;Jeyadevan et al 2000;Calvin et al 2002a).…”

“…For example, ZnFe 2 O 4 becomes ferrimagnetic, when prepared in the form of nanoparticles, because it adopts a partially inverted spinel structure (Sato et al 1990;Kamiyama et al 1992;Jeyadevan et al 1994;Hamdeh et al 1997;Ammar et al 2004). Using neutron powder diffraction, the degree of inversion X for ZnFe 2 O 4 nanoparticles prepared by co-precipitation was determined to increase with decreasing particle size from 0.108 at particle size 9.6 nm to 0.142 at particle size 2.9 nm (Kamiyama et al 1992).…”

Effect of Preparation on Structure and Magnetic Properties of ZnFe2O4

“…Recently, progress in synthesis techniques has initiated new surge of concern in ferrites to improve their physical properties and develop their applications [1][2][3]. Zinc ferrite has long attracted researcher's interests because of its intriguing magnetic properties compared with other spinel ferrites.…”

Structural investigations and magnetic properties of sol-gel Ni0.5Zn0.5Fe2O4 thin films for microwave heating

“…10,11 The observed high temperature magnetic ordering is attributed to the change in the cation distribution from the normal to the mixed spinel type where Fe 3+ and Zn 2+ ions occupy both sites. 12 NiFe 2 O 4 has the mixed spinel structure when the grain size is reduced to a few nanometers. 4 It exhibits noncollinear spin structure and the magnetic moment is appreciably lower than the value for the bulk material.…”