Application of FORC distributions to the study of magnetic interactions in ferrites of composition

Influence of the iron content on the formation process of substituted Co–Nd strontium hexaferrite prepared by the citrate precursor method

“…In a work by other authors [12], where Ba hexaferrite with La-Co substitution is studied, a stoichiomet- ric sample with La-Co substitution is compared to one with La excess (which implies an iron deficiency). They observe a very high coercivity of 6700 Oe for the iron-deficient sample and explain this considering that La excess both raises the anisotropy field and decouples the particles.…”

The influence of Nd–Co substitution on the magnetic properties of non-stoichiometric strontium hexaferrite nanoparticles

“…In a work by other authors [12], where Ba hexaferrite with La-Co substitution is studied, a stoichiometric sample with La-Co substitution is compared to one with La excess (which implies an iron deficiency). They observe a very high coercivity of 84.20 A/m for the iron-deficient sample and explain this considering that La excess both raises the anisotropy field and decouples particles.…”

“…In M-type hexaferrites, the 24 iron atoms of a unit cell occupy five different crystallographic sites: three octahedral sites, crystallographically known as 2a, 12k and 4f2, one tetrahedral site (4f1) and one bipyramidal site (2b). In the magnetically ordered state in BaFe 12 O 19 or SrFe 12 O 19 , the 12k, 2a and 2b sites have their spins aligned parallel to each other and to the crystallographic c-axis, whereas those of 4f2 and 4f1 point in the opposite direction.…”

“…For y ¼ x, the magnetic properties increase up to x ¼ 0.2 and then decrease due to the presence of secondary La and Co containing phases and to lateral grain growth during sintering [11]. It has also been observed that La excess induces the decoupling of particles, thus enhancing the coercivity [12]. However, the solubility of rare earth ions in Sr hexaferrites is very low and their introduction in the stoichiometry leads to the formation of secondary phases, which must be avoided in order to obtain permanent magnets with optimal properties.…”

Preparation and magnetic properties of La–Mn and La–Co doped barium hexaferrites prepared via an improved co-precipitation/molten salt method

“…In these studies, the magnetic properties of ferrites were changed by substituting Fe 3 + with other cations. The magnetic properties of ferrites can also be changed by substituting Ba 2 + (or Sr 2 + ) with La 3 + (or Pr 3 + , Gd 3 + ), [17][18][19][20], which alters the Fe 3 + -O-Fe 3 + super-exchange interaction, or along with lanthanide-doping, substituting Fe 3 + with ions such as Zn 2 + [21-23] Sn 4 + , Mn 2 + [24], and Co 2 + [25][26][27]. Mn 2 + was adopted as a dopant because it has the same number of unpaired electrons as Fe 3 + and would therefore provide a useful comparison to our previous work [16].…”