Impact of strontium substitution on the structural, magnetic, dielectric and ferroelectric properties of Ba1-xSrxFe

Enhancement in the dielectric and magnetic properties of Ni2+–Cu2+ co-doped BaFe11Cu1−xNixO19 hexaferrites (0.0 ≤ x ≤ 1.0)

“…2+ 4 Fe 3+ ions at the octahedral site, while the Fe 2+ /Fe 3+ ratio is determined by the conversion of dominant Fe 3+ to Fe 2+ via doping, sintering, and environmental conditions. 24,25 As can be seen in the graph, the 3 0 values rapidly decrease in the low-frequency region, while in the high-frequency region, they become nearly frequency independent. The Maxwell-Wagner polarisation model precisely explains this phenomenon, which is consistent with Koop's theory.…”

“…Fig.4(a) shows the behaviour of the real part of dielectric permittivity (3 0 ) versus applied frequency for the produced Ni 2+doped BaFe 11 Cu 1−x Ni x O 19 hexaferrites with x = 0.0, 0.25, 0.50, 0.75, and 1.0 measured at room temperature. Typically, the dielectric polarization in pure BaFe 12 O 19 is determined by the exchange of charges between the Fe 2+ 4 Fe 3+ ions at the octahedral site, while the Fe 2+ /Fe 3+ ratio is determined by the conversion of dominant Fe 3+ to Fe 2+ via doping, sintering, and environmental conditions 24,25. As can be seen in the graph, the 3 0 values rapidly decrease in the low-frequency region, while in the high-frequency region, they become nearly frequency independent.…”

Temperature induced structural and polarization features in BaFe12O19

“…[9][10][11] The ease of their synthesis, high corrosion resistance and stability of properties make hexaferrites attractive, for example, for usage as electromagnetic absorbers and permanent magnets for magnetic storage media. [12][13][14][15] Moreover, BaFe 12 O 19 is considered to be a promising multiferroic material showing a large spontaneous polarization 16 due to the appearance of a noncollinear magnetic structure 17,18 or to distortion of a single FeO 6 octahedron 19,20 or to the shift off the center trigonal bypiramid position of a Fe 3+ ion in a FeO 5 trigonal bipyramide. 21,22 However, in all these cases the crystal structure of the hexaferrite was assumed as unchanged centrosymmetric with the P6 3 /mmc space group where according to the Gorter model 2 all Fe 3+ cations were located in 5 nonequivalent crystallographic positions in the unit cell with three types of oxygen coordination (Fig.…”

Effects of Ca–Gd co‐substitution on the structural, magnetic, and dielectric properties of M‐type strontium hexaferrite

“…M‐type hexagonal ferrites (MFe 12 O 19 ) are crystallized in a hexagonal cell with P 6 3 / mmc space group and are made up of the S block constructed by Fe 6 O 8 and the R block composed of MFe 6 O 11 . The structure is described as SRS*R*, where the asterisk indicates that the corresponding block has been turned 180° around the hexagonal c‐axis 2,3 . The feature of high uniaxial magneto‐crystalline anisotropy of M‐type hexaferrite makes them suitable for permanent (hard) magnet applications and recording media 4 …”

“…The structure is described as SRS*R*, where the asterisk indicates that the corresponding block has been turned 180 • around the hexagonal c-axis. 2,3 The feature of high uniaxial magneto-crystalline anisotropy of M-type hexaferrite makes them suitable for permanent (hard) magnet applications and recording media. 4 Many researchers have conducted studies on the partial substitution of Fe sites in order to modify their electric and magnetic properties of M-type Srhexaferrites.…”