Coercivity enhancement of strontium hexaferrite nano-crystallites through morphology controlled annealing

Structure and magnetic properties of W-type hexaferrites

“…As Sr-containing hexaferrites in general do not always display the same cation distribution as Ba-containing hexaferrites (Albanese et al, 1973;Sizov, 1968), it is highly relevant and interesting to investigate both the cation distribution and subsequent magnetic ordering of the Sr-containing hexaferrites. Aside from the cation distribution, the crystallite size also has a huge impact on the macroscopic magnetic properties of hexaferrites (Gjørup et al, 2018) and is an important part of optimizing their performances.…”

Optimization of magnetic properties in fast consolidated SrFe12O19nanocrystallites

“…a linear increase in saturation magnetization with the size of the nanoparticles until the bulk value is reached 4 and an optimal crystallite size with relation to coercive force. 5 The magnetic nanoparticles have many interesting uses such as in contrast agents, 6 hyperthermia treatment, 7 magnetic sensors, 8 electromagnetic shielding nanocomposites, [9][10][11] or drug delivery. 12 In 2011 the manufacturing industry producing rare-earth permanent magnets (PM) encountered considerable difficulties with the supply chain of rare-earth metal, which became known as the rare-earth crisis.…”

Controlling structural and magnetic properties of SrFe12O19 nanoplatelets by synthesis route and calcination time

“…[7] However, commercial SrFe 12 O 19 magnets typically reach maximum values of up to 34 kJ m -3 . [7,8] One approach to attain BH max values closer to the theoretical one is to consider the strong dependency of the coercivity on the crystallite size. [9] If the crystallite size is reduced down to the critical single domain size, i.e.…”

“…Therefore, single domain crystallites in the upper limit of the single domain size region, i.e., close to the critical single-domain size, are favorable in order to maximize the coercivity. [7] The exact value of the critical single-domain size depends on the composition and morphology of the material. In the case of SrFe 12 O 19 , which crystallizes into hexagonal platelets, both the width of the crystallite and its thickness have to be taken into account.…”

“…For crystallite thicknesses of 62 nm, a critical single-domain size of SrFe 12 O 19 platelets of 282 nm in diameter has been calculated for platelet-shaped crystallites. [7] The strong size dependence of the coercivity illustrates that precise control of the crystallite size and shape are key to optimizing the magnetic properties of Sr hexaferrite. Crystallites typically grow during calcination processes.…”