R h r n 6 .-A partir du ferrite spinelle de base NiFe204, on a introduit des ions de rayon ionique de plus en plus grand, Zn2+ et Cd2+, avec une concentration x de plus en plus forte. Ces materiaux de composition Ni1-~Zn~Fe204 et Nil-zCdzFe204 ont ete preparbs en utilisant une technologic speciale. Le pas du rtseau croit linkairement avec le rayon moyen d'ion en site tetrakdrique. La variation de temperature de Curie due a une variation de distance entre les ions magnktiques est Cvaluie. La contribution la temperature de Curie due a la distribution des porteurs magnttiques est mise en Cvidence par une courbe unique hypothktique intercomposition. De la m&me facon, I'influence de la variation de distance entre les ions magnktiques sur I'aimantation Ms a kt6 determinee. Enfin les rbultats obtenus sur les spinelles sont compares avec ceux deduits de la litterature pour les grenats.
A method is proposed to determine the over-all anisotropy K in ferrimagnetic materials from initial susceptibility of single-domain grain samples. Indications on technology of single-domain grain samples are given. The Ni1−xZnxFe2O4 system is studied in detail. The upper limit of the contribution from dipolar energy has been determined by studying Mn0.5Zn0.5Fe2O4 and is found to be negligible. The study of magnetoelastic anisotropy has been carried out on compositions of known K1. This anisotropy (expressed as λsσ) varies very little at low temperatures depending on Zn content, and for a given composition it varies as λs. Thus, σ is temperature independent. σ is shown to be an intrinsic property for a composition and it increases with Zn content. Our investigations show that realization of single-domain grain samples enables us to obtain σ and K1 from measurements of (μ − 1)c, Ms, and λs, which are easily accessible from polycrystalline samples.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.