Influence of stoichiometry on hexaferrite structure

The Effect of Condensation on the Morphology and Magnetic Properties of Modified Barium Hexaferrite (BaFe12O19)

“…Generally, formation of α-Fe 2 O 3 can be prevented by choosing the Fe/Ba ratio in between 11.5:1 and 10:1, further decrease leads to the formation of another intermediate phase, barium monoferrite (BaFe 2 O 4 ). Fortunately, this phase can be removed by HCl etching [47]. In this way, Sozeri et al very recently succeed to synthesize high purity and high quality barium hexaferrite samples with an initial Fe/Ba molar ratio of 2:1 [48].…”

“…It is known that as the grain size increases, coercivity of the sample decreases. In fact, the coercivity is related to the reciprocal grain size rather than the grain size itself [47]. Pinning of the magnetization occurs at the grain boundaries, density of which decreases as grain size increases.…”

“…Pre-heating between 400℃ and 500℃ for several hours was reported as a key factor to prevent formation of α-Fe 2 O 3 phase in the sol-gel technique [22]. In this way, samples with coercive field of 5950 Oe and having magnetization of 70 emu/g have been synthesized [23].…”

Synthesis and Characterization of PEG-Sr Hexaferrite by Sol–Gel Conversion

“…In order to prepare highly homogeneous ultrafine particles of barium hexaferrite, several non-conventional low-temperature chemical methods were developed for the formation of ultrafine BaFe 12 O 19 particles in last few years. These methods employed co-precipitation [11][12][13][14], hydrothermal [15][16][17], solgel [18][19][20][21], microemulsion [22], citrate precursor [23], salt melt method [24], glass crystallization [25,26], sonochemical [27], combustion [28] and mechano-chemical activation [29,30]. The chemical co-precipitation method is a lowcost technique compared to the other mentioned methods, suitable for mass production.…”

Synthesis and structure of strontium ferrite nanowires and nanotubes of high aspect ratio

“…A recent investigation on the synthesis of SrM has shown that the M phase may be formed as a pure product in a non-stoichiometric mixture of precursor [18]. Surig et al [19] proposed that the low-temperature synthesis of hexaferrites Afflek et al [20] who synthesized barium ferrite powder by using the SHS method suggested that a small amount of barium volatilized during the combustion and post-calcination processes is responsible for using the excess barium. In the case of chemical synthesis routes, it has been proposed that a deviation from the stoichiometric formula should be considered due to variations in the solubility of the cation sources [21].…”