Investigation of structural and magnetic properties of Al substituted Ba0.9La0.1Fe12-xAlxO19 hexaferrites prepared by solid-state reaction method

Comparing the role of NaOH and NH4OH on structural and magnetic properties of spinel Ba ferrite synthesized by autocombustion method

“…The rising in coercivity value is expected to be occurred due to the transition of ferrite nanoparticles from multidomain state to single-domain state as a result of particle size reduction. The values of Ms in this study are comparable to that in [5,33] and higher than in [34] due to the difference in particle sizes and the elements that were substituted. The remanent magnetization Mr magnitudes of the two samples are somewhat approximated to each other and so as to the permeability (µp) at 50Oe.…”

“…Spinel ferrite owns the formula M2+Fe2O4, where M is a divalent ion metal, it has face centre cubic structure owning 8 formula units per unit cell, where oxygen ions represent the anion of the lattice [4]. Ba ferrite has two structures spinel or hexaferrite according to composition and crystalline structure [5]. Spinel Ba ferrite (BaFe2O4) is a ceramic material, it likes other inverse spinel ferrites but Ba 2+ cations occupy the octahedral sites [6].…”

“…Various methods were used to prepare spinel Ba ferrite. Sol-gel [5,15], ball milling [16], modified polyacrylamide gel route [17], solid state reaction [12] and autocombustion [18]. As a chemical synthesis method, the autocombustion approach by citric acid exhibited a good material quality.…”

Exploring the role of oxygen vacancies on the magnetic and electromagnetic absorption properties of La3+-modified M-type hexaferrite with Al3+ doping

“…The substitution of La 3+ ion in place of Ba 2+ ions can enhance the reduction of Fe 3+ to Fe 2+ cation along with the formation of oxygen vacancies due to localized charge transferred from lanthanum to iron [51]. This reduction mainly occurred at the 2a octahedral site of Fe, which is confirmed by the value of n B at low temperatures, calculated by using the relation n B = MwMS 5585 [52], where n B , and M w are the Bohr magnetron per molecular unit formula and molecular weight, respectively. If this reduction of Fe 3+ to Fe 2+ cation happens at the other site, the value of n B will be greater than 20 µ B /f.u [53].…”

Low-frequency electrical response related to oxygen vacancies in Al3+ substituted M-type hexaferrite

“…The partial or full substitution of the La 3+ cation for Ba 2+ /Sr 2+ in an M-type hexaferrite will convert some Fe 3+ into Fe 2+ at the 2a octahedral site. As a result, electron hopping between Fe 3+ and Fe 2+ will increase, resulting in an enhancement in dielectric and electrical transport properties [18]. In addition, extra electrons introduced by lanthanum will play a key role in uplifting the magnetocrystalline anisotropy.…”