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A series of Sr 2 Cu 2 Pr x Fe 28- x O 46 (x = 0.00 to x = 0.32 with a step of 0.08) hexagonal ferrite was synthesized by the heat treatment method, and heated at 1300 °C for 6 h. These samples were characterized using FTIR, XRD, FESEM, VSM, and low-frequency (20 Hz–2 MHz) dielectric measurements. FTIR investigation confirms the ferrite phase formation in all the samples. XRD investigation reveals that all samples possess the X-type as a major phase with a minor M-phase. FESEM images show smaller grain size ranges between 25.27 μm and 51.25 μm. EDX elemental analysis confirms the existence of constituent elements in synthesized materials. VSM analysis shows that prepared ferrites possess a soft magnetic nature, the saturation magnetization of heated samples was found in the range of 35.99 Am2/kg to 49.44 Am2/kg, and coercivity was observed in the range of 10.372 kA/m to 37.443 kA/m. Relaxation peaks have been observed in the loss tangent profile for x = 0.00, 0.08. The Nyquist plot for samples S1 and S2 represents the low-loss universal capacitance circuit, while samples S3 to S5 represent the parallel conductance-capacitance circuit. [ABSTRACT FROM AUTHOR]

X-type samarium-cadmium co-substituted hexaferrite with compositions Ba 2-x Sm x Co 2 Cd y Fe 28-y O 46 (0.00 ≤ x ≤ 0.08, and 0 ≤ y ≤ 0.4) were prepared at 1340 °C using a simple heat treatment technique. All heated samples were characterized using FTIR, XRD, SEM, VSM, Mӧssbauer, and low-frequency dielectric measurements. XRD analysis of prepared samples shows the formation of X as a major phase along with hematite. The M S value varied from 67.01 Am2/kg to 50.43 Am2/kg; whereas the H c value changed from 2.95 kA/m to 6.17 kA/m, A high value of M S (67.01 Am2/kg) is observed in the pure sample, and a very low value of H c (2.95 kA/m) is observed for x = 0.06, y = 0.3 compositions, but Mr/Ms < 0.5 confirm the multi-domain nature of prepared hexaferrites. Hysteresis loops of all samples are narrow, and confirmed that formed samples belong to magnetically soft. Mössbauer spectra of the three samples (S1, S3, and S5) show the existence of doublets. Significantly low values of coercivity, retentivity, and loss tangent in Sm–Cd substituted samples signified those prepared materials can be used to design electromagnets, transformer cores, electric motors, and maybe a potential candidate for lossless low-frequency applications. [ABSTRACT FROM AUTHOR]

M-type, Ba 0.4 Pb 0.6 Fe 12- x Co x O 19 (x = 0.00, 0.10, 0.20, 0.30, 0.40) hexaferrites, synthesized using citrate gel auto combustion method, and heated at 950 °C, 4 h for lossless applications. XRD analysis shows the development of the M-phase, along with PbM and hematite. The microstructural analysis reveals the stacking clusters of hexagonally shaped platelets. TEM image and SAED pattern of x = 0.3 composition shows polycrystalline nature and formed particles observed to fused with neighbouring particles. M − H loops of all samples reveal hard magnetic behaviour and possess multi-domain structure. The maximum saturation magnetization of 55.427 A m2/kg is observed in x = 0.10 composition and coercivity of prepared hexaferrites was found to vary from 0.058 T to 0.390 T. The cobalt substitution has a strong influence on the dielectric properties of prepared hexaferrites. The value of ac conductivity increases with cobalt substitution from x = 0.00 to x = 0.10, and followed by a reduction from x = 0.10 to x = 0.40. The same trend is observed for the dielectric constant. The low value of loss tangent for all compositions shows apt scope for lossless application. [ABSTRACT FROM AUTHOR]

Polycrystalline nanoparticles of M-type Ca(ZrCo) x Fe 12−2 x O 19 (0.0 ≤  x  ≤ 1.0) hexaferrites were prepared using a simple heat treatment method at a low heating temperature of 650 °C. Effect of cobalt-zirconium substitution on the structural, microstructural, magnetic and dielectric properties was investigated. XRD analysis indicates that all the samples possess a hexagonal structure with anti-ferromagnetic α-Fe 2 O 3 phase. The values of lattice parameters and cell volume found to be increased with increasing the cobalt-zirconium substitution along with the amount of α-Fe 2 O 3 phase. Crystal symmetry has not affected by Zr–Co substitution in prepared calcium hexaferrite samples but the position of diffraction peak [108] is found to shift towards a lower angle as an increase in the substitution of Zr–Co. The crystallite size found to vary between 12 and 17 nm. SEM images show agglomerated grains and surface morphology has changed with Zr–Co substitution. EDX analysis of typical samples revealed the presence of Ca, Fe, Co, Zr. The magnetic analysis revealed the formation of multi-domain structure. Room temperature Mössbauer spectra of prepared samples show that all five sextets are merged together with a paramagnetic doublet and it confirmed that the size of particles is very small in the nano range. Single and double semicircle arcs were observed in Cole-Cole plots, due to the contributions of grain and grain boundaries resistance. [ABSTRACT FROM AUTHOR]

• SrFe 12 O 19 -/NiFe 2 O 4 nanocomposites with different weight ratios were synthesized in presence of crown flowers extract • FTIR and XRD analysis show the presence of M, S phases • The hexagonal platelet for M and spherical particles for S phase were observed • H C and M S decreased with increasing the spinel phase. • M;S- 9:1, 8:2, 7:3, 6:4 belong to a hard ferrite, and 5:5 shows soft magnetic nature. • M:S- 9:1 and 8:2 show weak exchange coupling interactions, whereas 7:3 and 6:4 depict partial exchange coupling interactions, and 5:5 composite possesses perfect exchange coupling interactions. [Display omitted] SrFe 12 O 19 (M-type hexaferrite) and NiFe 2 O 4 (spinel) nano ferrite powders were synthesized in the presence of Calotropis gigantea (crown) flowers extract separately. SrFe 12 O 19 /NiFe 2 O 4 nanocomposites were prepared in the presence of crown flowers extract and the effect of different weight ratios (M:S – 9:1, 8:2, 7:3, 6:4, 5:5) on structural, microstructural, magnetic, electrical transport, and dielectric properties were studied. The average crystallite size of nanocomposites was found from 25 nm to 44 nm. In addition, it was observed that the crystallite size of the M-phase decreased when the spinel phase increased. XRD analysis depicts the presence of both M and S phases in composites. The M-H loops analysis of SrFe 12 O 19 /NiFe 2 O 4 composites indicates that the coercivity (3181–326 Oe), and saturation magnetization (57.5 Am2/kg. - 40 Am2/kg.) decreased when the spinel phase amount increased. Nanocomposites with weight ratios 9:1, 8:2, 7:3, 6:4 belong to a hard ferrite, while 5:5 shows soft magnetic nature. However, prepared composites possess a multi-domain structure. The weak exchange coupling interactions were found in composites 9:1 and 8:2, whereas the partial exchange coupling interactions were observed in composites 7:3, 6:4, and perfect exchange coupling interaction was noticed in 5:5. [ABSTRACT FROM AUTHOR]