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- PublicationEffect of calcination temperature on structural and magnetic properties of lightly lanthanum substituted M-type strontium cobalt hexaferrites(2020-01-01)A series of M-type lanthanum substituted strontium cobalt hexaferrites, Sr0.5Co0.5LaxFe12-xO19(x=0.0, 0.05, 0.15 and 0.2) was synthesized using the simple heat treatment method. The synthesized hexagonal ferrites were calcinated at 950°C and 1050°C for 3 hrs in a muffle furnace and then slowly cooled to room temperature. X-ray diffraction (XRD) technique and magnetic hysteresis loops were used to investigate the structural and magnetic properties of prepared samples respectively. The X-ray diffraction analysis of all the samples shows the presence of M- type hexagonal ferrite and hematite phases. Room temperature magnetic hysteresis loops analysis shows the increase in saturation magnetization with the increase in lanthanum substitution.
- PublicationInvestigation on structural, hysteresis, Mössbauer properties and electrical parameters of lightly Erbium substituted X-type Ba2Co2ErxFe28-xO46 hexaferrites(2020-04-15)A series of Erbium substituted X-type Ba2Co2ErxFe28-xO46 (x = 0.00, 0.04, 0.08, 0.12, 0.16, and 0.20) hexaferrites were prepared by the method of heat treatment. The obtained precursors were heated at 1350 °C for 6 h. XRD investigation reveals that x = 0.0 sample possesses X, W-type, and α-Fe2O3 phases, while Er- substituted samples show presence of X and W phases. The room temperature Mössabuer spectra have been fitted with five sextets. A variation in saturation magnetization (MS) is explained and supported by the Mössbauer spectroscopy. The maximum values of MS (52.29 Am2/kg) and anisotropy field-Ha (1370 kA/m) are found for x = 0.12 composition. Similarly, the maximum relative area (~69%) for spin up sites (k+a+b) is also found for x = 0.12 composition. Low frequency (20 Hz–2 MHz) dielectric response of all samples show normal behavior of ferromagnetic materials. The dielectric measurements reveal that the conduction in low frequency is due to grain boundary contributions and at the higher frequency it is due to grain contributions. AC conductivity is found to increase with frequency in all prepared hexaferrites. The substituted compositions can have potential applications in filter application due to soft ferrite behavior and low dielectric loss tangent.
- PublicationInvestigation of structural and microstructural properties of hematite synthesized in the presence of oleic acid(2020-05-04)In the present work, we report the structural and microstructural properties of hematite (α-Fe2O3) synthesized using the co-precipitation method. Oleic acid was used as a surfactant in the synthesis process to reduce the agglomeration. Prepared hematite samples were characterized using FTIR, XRD, SEM, DLS and UV-VIS spectroscopic measurements. FTIR analysis of α-Fe2O3 shows the presence of Fe-O bands in the wavenumber range of 400 to 750cm-1. X-ray diffraction analysis of hematite powder prepared without oleic acid confirms the formation of the pure phase of α-Fe2O3. SEM image reveals that the formation of spherical particles with an average size < 200nm and it is in a good agreement with particle size distribution observed from Dynamic Light Scattering. A UV-Vis spectroscopic result shows strong absorption in the UV region and weak absorption in the visible region.
- PublicationStructural, morphological, magnetic hysteresis and dielectric properties of cobalt substituted barium–lead hexagonal ferrites for technological applications(2021-10-01)M-type, Ba0.4Pb0.6Fe12-xCoxO19 (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.
- PublicationTailoring magnetic and dielectric properties of SrFe12O19/NiFe2O4 ferrite nanocomposites synthesized in presence of Calotropis gigantea (crown) flower extract(2022-04-15)SrFe12O19 (M-type hexaferrite) and NiFe2O4 (spinel) nano ferrite powders were synthesized in the presence of Calotropis gigantea (crown) flowers extract separately. SrFe12O19/NiFe2O4 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 SrFe12O19/NiFe2O4 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.
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- PublicationTailoring magnetic and dielectric properties of SrFe12O19/NiFe2O4 ferrite nanocomposites synthesized in presence of Calotropis gigantea (crown) flower extract(2022-04-15)SrFe12O19 (M-type hexaferrite) and NiFe2O4 (spinel) nano ferrite powders were synthesized in the presence of Calotropis gigantea (crown) flowers extract separately. SrFe12O19/NiFe2O4 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 SrFe12O19/NiFe2O4 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.
- PublicationInfluence of Pr-ion substitution in Cu2X hexaferrites on their magnetic and dielectric properties(2024-02-15)A series of Sr2Cu2PrxFe28-xO46 (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.
- PublicationA study of the effect of the Cu and Cr co-doping on structural, magnetic and dielectric properties of barium hexaferrites synthesized in presence of mentha leaves extract(2023-12-01)In the reported research work, we investigated the structural, thermal, magnetic, surface morphology, Raman spectroscopic and dielectric properties of Cu-Cr co-substituted M-type barium hexaferrites for lossless low-frequency applications. By using the green synthesis approach with mentha leaves extract, we synthesized a series of M-type BaCuxCrxFe12‐2xO19 (0.0 ≤x≤0.5) hexaferrite with varying Cu-Cr content. A simple heat treatment method was used to prepare hexaferrite samples. The samples were heated to 1100 °C and thoroughly characterized for their structural, thermal, magnetic, Raman spectroscopic and low frequency dielectric study. The results of XRD finding revealed the formation of M-phase along with secondary phase of BaFe2O4. The Raman spectroscopic analysis shows the successful replacement of Cu and Cr ions in place of Fe ions, and the substituted samples hold the hexagonal shape as visible from FESEM images. All samples show a hard magnetic nature with multi-domain structures, and x = 0.2 composition has a maximum Ms of 68.99 Am2/kg and lowest Hc of 0.1 T. Cole-Cole graphs show shifting of peaks position with Cu-Cr substitutions and increasing frequency, which gives the insight of the role of grain and grain boundaries. These findings open up exciting possibilities for using these hexaferrites in loss-less, and low-frequency applications.