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5–15 mol % UO3 loaded zinc iron phosphate glass was prepared by melt quench process. The solubility of UO3 in ZnIP was determined by XRD and was found to be below 15 mol %; beyond which separation of UP2O7 compound was observed. Mossbauer spectroscopy unraveled the ratio of Fe (II)/Fe(III) and was found to decrease from 0.071 (ZnIP) to 0.029. EXAFS studies unraveled the prevalence of two type of coordination for U–O (i.e U–O1 and UO2) and Fe–O (Fe–O1 and Fe–O2) in the ZnIP glass matrix, whereas a single chemical environment for Zn–O in the same glass matrix.

Different concentrations of ZnFe2O4 and manganese substituted ZnFe2O4 nanoparticles (10%, 20% and 30%) dispersed poly(o-phenylenediamine) (PoPD)/ferrite nanocomposites have been prepared by in-situ oxidative polymerization method. The synthesized nanocomposites have been characterized by spectroscopic, microscopic techniques, thermal and dielectric properties analyzed at different temperature and frequency. The XRD pattern revealed that there is a good interaction between PoPD and ferrite nanoparticles. The crystalline size of ferrite nanoparticles are changed when it is dispersed in PoPD. The morphology of PoPD is modified by ZnFe2O4 nanoparticles into sheet like morphology. The Mossbauer spectra of ferrite nanoparticles are indicated that iron present in Fe3+ high spin state. The magnetic studies of ferrite nanoparticles and PoPD/ferrite nanocomposites are exhibited ferromagnetic magnetic nature and saturation magnetization of PoPD/ferrite nanocomposites increases with increase concentration of nanoparticles. The PoPD/ZnFe2O4 has higher dielectric constant than PoPD/MnZnFe2O4. The AC conductivity of PoPD/ferrite nanocomposites are increased with increasing in frequency and temperature.

High resolution TEM studies revealed the spherical morphology of MxCe1-xO2 (M = Co, Fe or Ti, x = 0.05) particles with their size in the range of 8–11 nm. Raman, UV and PL spectroscopy analyses evidenced that oxygen vacancy concentration modified with the type of dopants. The concentration of vacancies in the Co0.05Ce0.95O2 sample was relatively higher and hence it had optimum magnetization value. The in-vitro cytotoxicity study for MxCe1-xO2 (M = Co, Fe or Ti, x = 0.05) nanoparticles against human lung adenocarcinoma (A549 cells) was conducted. The results suggested that at a 10 μg/mL concentration, the undoped CeO2 nanoparticles have shown cell viability up to 99%. In contrast, at the same concentration, the doped CeO2 such as Co0.05Ce0.95O2, Fe0.05Ce0.95O2 and Ti0.05Ce0.95O2 nanoparticles demonstrated the cell viability of ~97%. Furthermore, the samples displayed reliable biocompatibility up to 1000 μg/mL concentration. Interestingly, Co-doped CeO2 nanoparticles exhibited relatively higher biocompatibility against A549 cells at all concentrations. Further, the higher amount of vacancies might have improved the free radical scavenging effect and so the biocompatibility for the samples.

Controlled synthesis pure-phase Bi0.98Tb0.02Fe1−xCoxO3 (BTFCO, x = 0.01, 0.03, 0.05 and 0.07) nanoparticles with rhombohedral structure using a facile sol–gel method opens the doors to robust their magnetic and photocatalytic properties significantly. The microstructure analysis revealed improvement in the surface morphology with a decrease of average particle size from 64 to 38 nm. No mixed valance state of iron detected for any sample, which is confirmed by Mossbauer spectra. The saturation magnetization and remnant magnetization were increased dramatically from 0.802 and 0.118 emu/g for BFO to 2.261 and 0.737 emu/g, respectively by Tb, Co co-doping. The enhancement of the magnetic property is attributed to the breakdown of spin cycloidal structure, spin canting, and uncompensated spin on the surface of nanoparticles. Furthermore, the as-synthesized samples are highly effective for rhodamin B (RhB) degradation under visible light irradiation, and the possible photocatalytic mechanism discussed in detail. Bi0.98Tb0.02Fe0.93Co0.07O3 nanoparticles exhibit the best photocatalytic activity owing to their larger specific surface area, lower band gap, and reduced average particle size. Besides, 1.2% efficiency retention for the degradation of RhB dye using BTFCO7 after the 20th cycle suggests a potential candidate to address the current scenario in the environmental remediation technology.

Co4+-Ca2+ substituted M-type barium strontium hexagonal ferrites with chemical composition Ba0.25Sr0.75CoxCaxFe12-2xO19 (x = 0.0, 0.2, 0.4, 0.8, 1.2, 1.6 and 2.0) were prepared by sol-gel auto combustion technique and sintered at 1150 °C for 5 h. The structural, magnetic, electrical and impedance properties of prepared samples were characterized using FTIR, XRD, SEM, VSM, Mossbauer spectroscopy and impedance spectroscopy. The FTIR spectra displayed two absorption bands in a wave-number range from 600 to 550 cm−1 and 450 to 400 cm−1 that confirm the formation of hexaferrite. XRD analysis of x = 0.0 and x = 0.2 compositions show the formation of the majority of hexaferrite M-phase, while other samples show M-phase with other phases in the prepared compositions. The substitution of Co–Ca reduced the coercivity (HC) from 3135.45 Oe (x = 0.0) to 48.28 Oe (x = 0.8) and saturation magnetization (MS) decreased from 65.97 emu/g (x = 0.0) to 42.24 emu/g (x = 2.0). Mossbauer spectroscopic analysis showed that each sublattice has five sextets that can be attributed to the Fe+3 ions in the high spin state and few Fe3+ ions were converted into Fe2+ ions for compositions x ≥ 0.8. Single semicircle curves were observed in Nyquist plots, attributed to the contributions of grain boundaries. Impedance and Nyquist plots depicted non-Debye relaxation in the compositions. AC conductivity of all samples increases with the increase in frequency. The microstructure accompanied by grain and grain boundaries influenced the electrical and impedance properties.

Structural and elastic properties have been investigated for a series of heat treated NixCu0.1Zn0.9−xFe2O4 (x = 0.5, 0.6, 0.7) nanoferrite powders which were synthesized using co-precipitation method. Rietveld refinement patterns revealed the spinel phase belonging to fd3m space group. Lattice parameters of the heat treated samples are in the range of (8.453–8.417 A). As the substitution level of Ni2+ increased, the lattice parameter decreased in the samples sintered at 200 °C, but it was randomly varied in the in the samples sintered at 500 °C. The average crystallite size (4.1–10.9 nm) estimated from XRD as well as average particle size (5.5–11.3 nm) estimated from FE-SEM were found to be increased with the increase of Ni2+ ion concentration in sintered ferrite samples. Sintering process was promoting the growth of nanoparticle size. The spherical nature of ferrite nanoparticles was evident from the FE-SEM micrographs. The vibrational bands observed in the FTIR spectra confirm the cubic spinel phase of ferrite systems. The variation of vibrational bands seems to be dependent on the particular metal ion occupying the spinel structure rather than the changes in bond lengths of Fe3+–O2− ion complexes. The present values of elastic moduli revealed the mechanical hardness of present heat treated ferrite samples. Interestingly, the elastic moduli depend upon the variation of both inter-atomic distances as well as cation redistribution. The identical value of Poisson’s ratio (0.35) is an authentication of isotropic behaviour of the present ferrite systems.

MgFe2O4 ferrite was synthesized in the presence of Solanum Lycopersicum fruit extract using sol–gel auto-combustion technique and heated from 650 °C to 1050 °C with the difference of 100 °C. The effect of heating temperature on phase purity, crystal structure, and magnetic as well as dielectric properties was systematically investigated. XRD analysis show that all samples consist of a single phase cubic spinel structure. The average crystallite size of heated samples varied from 10 to 26 nm, it was observed that crystallite size increases with the calcination temperature and average grain size was found in between 18 and 65 nm. SEM micrographs show that there is a drastic reduction in the grain size in the sample prepared in presence of tomato extract (65 nm) compared to the sample prepared without tomato extract (373 nm) and heated at 1050 °C for 4 h. All samples belong to soft ferrite (HC ~ 10 to 70 Oe) and possess a multi-domain structure. As heating temperature increases the values of both saturation magnetization (MS) and hyperfine magnetic field (Hhf) are found to increase. The frequency-dependent dielectric phenomenon was observed in all prepared samples and single one-fourth semi-circles observed in Nyquist plot because of the contribution of the grain boundaries over the grain conductions. M″ and Z″ vs frequency plots reveal the absence of Debye relaxation in prepared compositions.

Bismuth-substituted CeO2 (Bi0.05Ce0.95O2) nanostructured material have displayed room temperature ferromagnetic behavior. The substitution of Ce ions with Bi3+ ions decreased the saturation magnetization (MS) value of CeO2. UV-Vis and photoluminescence spectroscopic analyses revealed the occurrence of defect states i.e. surface oxygen vacancies in the sample, which facilitated ferromagnetic interactions in the Bi-substituted CeO2 nanostructures. Further, the clusters in the sample could provide antiferromagnetic interaction amongst ions, which reduced the MS value of CeO2. The clusters in the annealed sample was substantiated from its ZFC/FC curve. X-ray photoelectron spectroscopy analysis revealed the presence of Bi3+, Ce3+, and Ce4+ ions in the sample. High-resolution transmission electron microscopy (HRTEM) images suggested the spherical and rod-shaped morphology for the particles.

In the present study, Cu-substituted M-type lead hexaferrites with chemical composition PbCuxFe12−xO19 (x = 0.0, 0.2, 0.4, 0.6, 0.8, and 1.0) have been synthesized using a co-precipitation method. As-obtained precursors were preheated at 550°C for 4 h in a muffle furnace, followed by final heating at 1150°C for 5 h. All heated samples were characterized using various instrumental techniques like Fourier transform infrared (FTIR), x-ray diffraction (XRD), Mossbauer spectroscopy, vibrating sample magnetometer (VSM), and low-frequency dielectric measurements to investigate the effect of copper substitution on the structural, magnetic, and dielectric properties. FTIR spectra of all heated samples showed two absorption bands confirming the formation of ferrite. XRD analysis of all samples confirmed the formation of a majority of M-type hexaferrite phase with secondary phases. The coercivity (HC), saturation magnetization (MS), and remanence magnetization (Mr) are found to decrease with copper content (except the x = 1.0 composition). The coercivity is found to change from 8 kA m−1 to 27 kA m−1, and this depicts the magnetically soft nature and multi-domain structure of the prepared ferrites. Mossbauer spectra indicate that the 12k site is more affected by Cu substitution. This means that Cu prefers to occupy the 12k site, which increases the ferrimagnetic order and reduces the saturation magnetization. The dielectric study of all heated samples showed the frequency-dependent phenomenon. Each composition showed a single semicircular arc due to contributions of grain and grain boundaries resistance in Cole–Cole plots.

Recently the core-shell nanostructures are employed for various applications. In this trend, ϵ-Fe3N@Fe3O4 (INIO) magnetic nanoparticles (core/shell structured) were synthesized by a solvothermal process followed by calcination. The X-ray diffraction (XRD), selected area diffraction pattern (SAEDP), X-ray photoelectric spectroscopy (XPS) and Mossbauer spectroscopy validates the formation of the spherical core-shell structure of the ϵ-Fe3N@Fe3O4 nanoparticles having size range (5–32 nm). The saturation magnetization values for the sample at ±2 T field were around 128 and 99 Am2/kg at 5 and 300 K respectively. The values were higher than the known values for iron oxide nanoparticles. The pluronic acid (F-127) based ferrofluid of these nanoparticles, displayed excellent stability (Zeta potential values) and good heating ability (external AC magnetic fields). The best specific loss power was found to be around 90 W/g at 23 mT field. The cell viability with human lung adenocarcinoma A549 cells was observed to be 88 and 85% at 1 mg/mL for these nanoparticles after the treatment for 24 and 48 h respectively.

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 Mossabuer spectra have been fitted with five sextets. A variation in saturation magnetization (MS) is explained and supported by the Mossbauer 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.

For advanced lithium-ion battery technology, olivine-based cathodes are considered to be the most dominant and technologically recognized materials. The extraction of lithium ions from olivine LiFePO4 results in the two-phase mixture with heterosite FePO4 exhibiting a deintercalation potential of 3.45 V vs. Li+/Li over a wide range of lithium content. Here, we report the synthesis and characterization of chemically deintercalated heterosite FePO4 with varying crystallite sizes using different analytical techniques. The decrease in the crystallite size of heterosite FePO4 leads to an increase in the lattice parameters including the unit cell volume. The characteristic behavior in the structural properties of heterosite FePO4 shows a strong dependency on the crystallite size which is correlated with the change in the chemical bonding. The volume expansion of the nano-sized heterosite FePO4 with respect to the bulk counterpart is suggested to be a direct consequence of reduced hybridization between the Fe3d and O2p states. Furthermore, the combined X-ray diffraction and Mossbauer spectroscopic studies reveal the appearance of a new phase namely trigonal FePO4 at the lower crystallite sizes due to the enhanced surface energy kinetics. We also find that the observed trigonal FePO4 phase is more magnetically active than the paramagnetic olivine FePO4. For the unique structural advantage of the heterosite phase as an electrode material, the change in bonding characteristics is very useful and can have strong implications on the electronic properties of heterosite FePO4 at the nanoscale level.

Multiferroic particulate composites have been fabricated by taking the morphotropic phase boundary composition of ferroelectric phase Bi(Ni1/2Ti1/2)O3–PbTiO3 and magnetic phase (Ni,Zn)Fe2O4. The ferroelectric phase has coexisting monoclinic and tetragonal perovskite structures with space group Pm and P4mm, respectively whereas the magnetic phase has spinel cubic structure with space group Fd 3 ‾ m. Rietveld structural analysis for the each components of composite reveals that the tetragonality (c/a) of the ferroelectric phase continuously increases with increasing the concentration of magnetic phase and finally transform in rhombohedral (R 3 ‾ c) phase suggesting partial ionic diffusion between ferroelectric and magnetic phases. Composition dependent Mossbauer spectra of (1-x)Bi(Ni1/2Ti1/2)O3–PbTiO3/x(Ni,Zn)Fe2O4 reveals the superparamagnetic like behavior for the ferroelectric rich composition with x = 0.2. The magnetic ordering increases for the composition with x = 0.4 and 0.6 which completely transforms into ferrimagnetic for the composition with x = 0.9. Unlike the ferroelectric or magnetic components that do not exhibit the magnetoelectric response separately, significant value of magnetoelectric coefficient (> 30 mV/Oe-cm) in (1-x)Bi(Ni1/2Ti1/2)O3–PbTiO3/xNi0.6Zn0.4Fe2O4 composite makes it promising for multifunctional applications.

In this article, we demonstrate the synthesis of single phase Bi 1- x Sr x Fe 1-y Co y O 3 (x = y = 0, x = 0.02; y = 0.01, 0.03, 0.05, 0.07) using a facile sol-gel route. The powder X-ray diffraction measurements of all the samples confirm the pure phase rhombohedral structure with a small lattice distortion. The morphological analysis demonstrated decrease in average particle size from ~ 64 to 41 nm with increasing Co doping in Bi 0.98 Sr 0.02 Fe 1- y Co y O 3 due to slower growth rate. Mossbauer study reveals the change in oxidation state of iron (Fe 3+ → Fe 2+ ) at higher doping concentration of Co. Further, the successful co-doping of Sr, Co into BiFeO 3 lattice remarkably enhances the saturation magnetization value from 0.8 emu/g to 2.3 emu/g and remnant magnetization from 0.08 emu/g to 0.532 emu/g. The enhanced magnetic properties of Sr, Co co-doped BiFeO 3 nanoparticles is ascribed to the breaking of cycloidal spin structure, more number of uncompensated spin on the surface, and oxygen vacancies. Moreover, these samples were found to be highly efficient for the degradation of Rhodamin B (RhB) dye under visible light irradiation. The best RhB degradation activity was observed with 7% Co doping Bi 0.98 Sr 0.02 Fe 1- y Co y O 3 (BSFCO7) due to its lower bandgap, reduced average particle size and larger specific surface area.

In the present communication, the effect of Zr substitutions in cobalt oxide (ZrxCo3−xO4, where x = 0.01, 0.05, 0.1, 0.3 and 0.5) nanoparticles over their structural, magnetic and electric properties have been investigated. The nanoparticles were produced by single step microwave refluxing method. The crystallite size was found to be diminishing with increased Zr concentration. All the samples displayed weak ferromagnetic behavior. The continuous decrease of MS value of Co3O4 nanoparticles was noticed upon an increase in the Zr substitutions. AC conductivity and dielectric measurements were carried out in the frequency ranging from 10 kHz to 20 MHz. The samples with the highest zirconium concentration, i.e. x = 0.5 have shown relatively moderate conduction as well as dielectric properties.

This study presents a detailed crystallo-chemical characterization of glauconites occurring at different stratigraphic intervals within the phosphorite-bearing Campanian Duwi Formation. While authigenic glauconites occur within the shallow marine, transgressive deposits of Abu Tartur Phosphate and Maghrabi Shale Members in the Campanian Duwi Formation, allogenic variety occurs within the regressive deposits at the top of the Liffiya Shale Member. Nascent to slightly evolved, shallow-marine originated authigenic glauconites are distinct by a high content of MgO. A good correlation between K2O and Fe2O3(total) contents of glauconites in the Maghrabi Shale supports ‘layer lattice’ theory while a combination of ‘layer lattice’ and ‘verdissement’ theories explain the origin of other glauconites within the Duwi Formation. X-Ray Diffraction studies reveal a ‘true’ di-octahedral nature and 1M ordering of the glauconite pellets with smectite inter-stratification. Mossbauer spectroscopic study reveals Fe3+ as the dominant cation in the octahedral site that preferentially occupies the less distorted cis M(2) sites. Glauconites acquire a high Mg-content because of the passage of Mg- and Ca-rich fluid that leads to extensive dolomitization. Glauconites form at the transition zone between black shale and phosphate, representing oxygen-depleted conditions. Similar shallow marine glauconites occur all along the paleo-Tethyan margin during the Late Cretaceous time.

Magnetic materials with high specific loss power (SLP) are desirable for magnetic hyperthermia to minimise the amount of material required to obtain the therapeutic temperature (42–46 °C) to destroy the cancer cells. The exchange coupled core-shell structure and the nanoclusters of magnetic nanoparticles having high SLP values are the most suitable candidates for this purpose. Herein, a simple method has been demonstrated for the synthesis of exchange coupled magnetic nanoflowers consisting of γ-Fe2O3 magnetic grains grown over the surface of MnFe2O4 core. The aqueous ferrofluid of nanoflowers displayed higher SLP values than single phase MnFe2O4 core. The intrinsic loss parameter for the nanoflowers was 3.30 nH m2 Kg−1 at an applied magnetic field of amplitude 250 Oe and frequency 113 kHz, which was significantly higher than the commercially available ferrofluids. The cytotoxicity of the nanoflowers were studied with HeLa cells. The magnetic hyperthermia treatment for 30 min with 0.75 mg/mL ferrofluid of the nanoflowers demonstrated a temperature rise to 46 °C and decreased the cell viability to 17% for HeLa cells. These nanoflowers (size around 40–60 nm) showed better magnetic properties viz. higher saturation magnetisation, initial susceptibility and lower coercivity, making them a suitable candidate for biomedical applications.

It remains a challenge to enhance the multiferroic properties of perovskite materials. Herein, we demonstrate a facile sol-gel synthesis of BiFeO3 and Bi0.98Ho0.02Fe1-xCrxO3 (x = 0.01, 0.02, 0.03 and 0.04) nanoparticles with an average size range of 71–35 nm. The crystal phase and structure of as-synthesized powders are studied using Rietveld refinement, which reveal 100% perovskite phase with rhombohedral R3c structure. A saturated loop with small remnant magnetization (Mr) reflects weak ferromagnetism in all the samples. The dc magnetization along with Mossbauer spectroscopy confirms ferromagnetic nature of the compounds. Further, it is to be noted that the co-doping enhances the saturation magnetization to almost three times more than that of pure BiFeO3 and related mechanism was studied in details. Simultaneously, the ferroelectric polarization (Pm) was found to increase from 0.44 μC/cm2 (pure BiFeO3) to 2.08μC/cm2 (Cr doped Bi0.98Ho0.02FeO3). The co-doped samples show high resistivity which is confirmed by the decrease of loss tangent (tanδ) from 3.6 to 0.17 due to the reduction of oxygen vacancies. The band gap of as prepared samples was also found to increase at higher Cr concentration. To the best of our knowledge, for the first time, we have attempted to enhance the multiferroic properties of BiFeO3 using Cr and Ho as co-dopants.

Fe3C magnetic nanoparticles were synthesized by solvothermal assisted technique. The X-ray and electron diffractions have confirmed the formation of monophasic iron carbide (Fe3C) nanoparticles. Transmission electron microscope analysis validated that the size of the particles was around 19–34 nm. The presence of only Fe and C in Fe3C was asserted by X-ray photoelectron spectroscopy (XPS). The room temperature Mossbauer spectroscopy also corroborates the occurrence of only this carbide phase. The saturation magnetization at ±2 T and at 300 K was obtained to be around 88 Am2/kg with a coercivity of 17.3 mT and remanence of 6 Am2/kg. The oleic acid based ferrofluid of this carbide nanoparticles exhibited good heating ability in the presence of external alternating current (AC) magnetic fields. The optimum specific absorption rate and intrinsic loss power values were 85 W/g and 0.97 nHm2/kg at 23 mT and 261 kHz. Due to lack of reports on magnetic hyperthermia response for iron carbides, the values were compared with iron oxides. The values were found to be comparable.

The single phase LixFe3-xO4 (0.06 ≤ x ≤ 0.3) nanoparticles were synthesized using microwave refluxing technique and found to be spherical with the size in the range of ∼ 3–22 nm. The structure and the size were confirmed by X-ray diffraction patterns and transmission electron microscopy. X-ray photoelectron spectroscopy data of Li0.3Fe2.7O4 sample indicate the oxidation states for Li-ions (+1) and Fe-ions (+2 and + 3). The sample Li0.06Fe2.94O4 had superior magnetization value (∼54.1 Am2/kg) and it diminished with increasing Li content. The low coercivity values and the presence of a doublet in Mossbauer spectra advise the presence of both ferrimagnetic and superparamagnetic component. The ferrofluids of these samples show magnetic field dependent stabilization of temperature near 42 °C at the time of magnetic hyperthermia experiments. The specific absorption rate value (up to 100 W/g) found to be comparable with the literature values.

Co-precipitation synthesizing technique was adopted to prepare manganese doped zinc ferrite nanoparticles with varying concentrations 0.5, 0.6, 0.7. EDX proved the consistency of stoichiometry of compositions in the ferrite samples considered under preparation. XRD patterns authenticated the ferrite phase in the investigating samples. The experimental lattice parameter (8.412–8.438 A) is increasing and crystallite size (7.6–6.4 nm) appears to be decreasing with substitution of Mn2+. The grain size (1.1 µm) in the sample (x = 0.7) with smaller crystallites (6.4 nm) is found to be bigger than that of remaining compositions (x = 0.5, 0.6). The vibrational frequencies detected in the FTIR spectra also authorized the obtained spinel phase in the current ferrite systems. The elastic moduli illustrate the mechanical strength of ferrite systems which are dependent on interatomic distances. The variation of line width and Lande's g–factor in ESR studies revealed the possibility of core-shell morphology of present ferrite nanoparticles.

Inspired by the nano-segregation of ionic liquids (ILs) into bi-continuous structures constituting of arrays of ionic and non-ionic components, herein, a new and sustainable strategy for preparation of mesh-like nano-sheet α-Fe2O3 nanoparticles and their photo-catalytic activity under sunlight, is presented. For the purpose, metal (iron) containing ionic liquids (MILs), 1-alkyl-3-methylimidazolium tetrachloroferrates, [Cnmim][FeCl4], (n = 4, 8 and 16), which not only act as precursors and solvents but also as structure directing agents have been used. Thus prepared NPs show MIL dependent structural, photophysical and magnetic properties. The catalytic efficiency of NPs has been tested for the photo-degradation of organic dyes (Rhodamine B) in aqueous solution under sunlight. The NPs are found to exhibit comparable catalytic efficiency under sunlight as compared to that observed under high intensity visible lamplight, without showing a decline in their catalytic efficiency even after 4 catalytic cycles. It is anticipated that the present work will provide a new platform for preparation of sunlight active nanomaterials for photo-catalytic applications with control over the structural and physical properties via varying the molecular structure of MILs.

Herein, cobalt-substituted iron carbide (CoxFe3−xC, 0 ≤ x ≤ 0.3) magnetic nanoparticles (15–30 nm) were prepared by a sol–gel assisted route. X-ray diffraction (XRD) and electron diffraction patterns suggested that all the samples had a single phase structure. Furthermore, Mossbauer spectroscopy validated the monophasic nature of all the Co-substituted iron carbides, except for x = 0.3. The results of Mossbauer spectroscopy for this sample indicated the presence of the Fe–Co alloy along with the carbide phase. The saturation magnetization value was found to decrease with an increase in Co concentration (x ≤ 0.16); however, it increased for the x = 0.3 sample due to the presence of a secondary phase (Fe–Co alloy). Ferrofluids of the pure and Co-substituted iron carbides in oleic acid exhibited good heating abilities during the magnetic hyperthermia experiment at different external fields.

The effect of iron deficiency on the structural, electrical and magnetic properties of the nano PbFe12-xO19-δ (where x = 0.0, 0.25, 0.50, 0.75 and 1.0) hexaferrites prepared by sol-gel auto combustion and further processed by microwaves is presented. The structure studied using transmission electron microscope (TEM) showed hexagonal cylindrical particles with an average size of ∼20 nm. Selected area electron diffraction (SAED) reflected highly crystalline nature of these nanoparticles. From the dielectric characterizations ac-conductivity, dielectric constant and loss tangent are analysed for pure and modified PbFe12-xO19-δ hexaferrites. The magnetic analysis revealed the formation of single-domain structure. Saturation magnetization (MS) decreases from 63.2 (x = 0) to 38.2 (x = 1.0) emu/g with increasing the Fe ions deficiency. Room temperature Mossbauer spectra show five sextets for all compositions confirmed the single phase formation. The relative area of 12k (↑) site decreases and 4f2 (↓) increases drastically with increasing the Fe ions deficiency in Pb-hexaferrites.

Gallium substituted Z-type Sr3GaxCo2-xFe24O41 (x = 0.0–2.0 in steps of 0.4) hexaferrites were synthesised by the sol-gel auto-combustion process, and sintered at 1150 °C. The structural, morphology, magnetic, Mössbauer, dielectric and microwave absorption properties were examined. XRD results of x = 0.0, 0.4, 0.8, and 1.2 samples show the formation of a single Z-type hexagonal phase. The samples x = 1.6 and 2.0 show the formation of Z and M phases. Hysteresis loops analysis suggest that samples x < 1.6 possess a soft magnetic nature, while the samples x = 1.6 and 2.0 show a hard ferrite characteristics. All samples possess multi-domain microstructures. The composition x = 0.4 [maximum MS = 97.94 Am2kg−1] was fitted with seven sextets (Fe3+) and a paramagnetic doublet-A (Fe3+), while beyond x ≥ 0.8 two more doublets (Fe2+) were observed along with seven sextets in Mössbauer spectra. The maximum values of Fe2+ ions (1.26%) and relative area of paramagnetic doublets (1.91%) were observed for x = 1.6 composition, which is also responsible for the lowest value of MS (69.99 Am2kg−1) for this composition. The average hyperfine magnetic field was found to decrease, whereas average quadrupole splitting was found to increase, with Ga-substitution. The substitution of Ga ions enhanced permeability, dielectric constant, magnetic loss and dielectric loss, in a non-linear fashion. The reflection loss was maximum at lower frequencies for samples x = 0.0 and 0.8, and decreases with frequency. Sample x = 0.8 has maximum reflection loss of −12.44 dB at 8 GHz, a measured thickness of 3 mm, and a bandwidth of −10 dB at 1.18 GHz. The observed absorption has been discussed with the help of the input impedance matching mechanism and quarter wavelength mechanism. The observed coercivity in different samples also influenced microwave absorption which demonstrated potenial in microwave absorber applications. published

Various quantities of ginger (Zingiber officinale) root extract were used to prepare X-type Barium–Zinc hexaferrite with the chemical composition Ba2Zn2Fe28O46. The powders were prepared using a combustion treatment method, being pre-heated at 550 °C for 4 h with the ginger as a fuel, followed by final heating to 900 °C for 5 h and natural cooling to room temperature to obtain Ba2Zn2Fe28O46 hexagonal ferrite powder. The phase composition of heated powder samples was investigated by X-ray diffraction (XRD), indicating the formation of a mixture of X-type and hematite (α-Fe2O3). Up to 82.6%, X-ferrite was formed at 900 °C with 52.5 g of ginger root extract. Dielectric analysis of the prepared samples shows the frequency-dependent phenomena. All samples were hard magnets, with coercivity values (HC) between 262.2 and 318.3 kA m−1, and squareness ratios > 0.5. The sample prepared with 52.5 g ginger root extract possesses the highest value of saturation magnetisation (MS = 33.87 Am2 kg−1) in comparison with the other prepared samples. Therefore, ginger was shown to be a useful natural plant extract as a reducing fuel for the low-temperature synthesis of X-ferrites. The sample prepared with 35 g ginger root extract shows a broad loss tangent resonance peak between 10 kHz and 100 kHz, while other samples show loss tangent resonance peaks between 300 kHz and 2 MHz frequency range.

Variations of Curie temperature and strength of magnetic phases with sintering temperature and Ni concentration is investigated in the present work. The AC susceptibility studies show a decrease in Curie temperature (TC) with an increase in Ni concentration in the samples. Comparison of Curie temperatures with the reported results reveals that samples in the present work show higher TC enabling high thermal stability. The Mossbauer spectra of nano- and sintered Ni-Zn ferrite samples were recorded at room temperature to monitor the local environment around Fe cations through Mossbauer hyperfine parameters as a function of composition and sintering temperatures. The increase in sharpness of the Mossbauer sextet with an increase in Ni concentration and sintering temperature corroborate improvement in homogeneity and ferrimagnetic ordering. The results of hyperfine parameters offer the possibility of having close view on configuring Curie temperature through monitoring hyperfine field by altering sintering temperature and/or Ni concentration. As the temperature dependence of magnetic and magnetoelastic properties is strongly influenced by the Curie temperature, the successful possible configuration of Curie temperature in the present work can be further investigated for desired sensor applications.

Cobalt substituted nickel spinel ferrites were synthesized in the form of Ni 1 - x Co x Fe 2 O 4 ( x = 0 - 1 , Δ x = 0.15 ) via Pechini’s sol–gel citrate method with final sintering at 1000 °C for 6 h. Structural purity of the prepared ferrites is examined by using X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). Thermo-gravimetric and differential thermal analysis (TG-DTA) show that the formation of spinel phase is completed upto 700 °C. Lattice constant, cationic distribution and cationic site parameters are estimated from XRD data. For the first time, lattice parameter ( a ) is determined using four different methods and quite similar values are obtained in those. Characteristic peaks of nickel ferrites are observed in the Raman spectrum of each ferrite composition. Grain size (80–95 nm) is observed to be higher than crystallite size (26.2–31.8 nm) due to agglomeration of grains. Mossbauer spectra recorded at 300 K temperature show the presence of iron in only +3 valency. Variations of isomer shift, hyperfine field, quadrupole splitting and line width are analyzed with the amount of doped cobalt. This paper also presents the electromagnetic and shielding properties of these Ni–Co ferrites in X-band (8.2–12.4 GHz) frequency range using vector network analyzer (VNA). The analysis of shielding effectiveness shows that increasing the amount of cobalt in nickel ferrites results in increase in shielding efficiency of the ferrites which proves the utility of this specific doping.

Nanoferrites with the chemical equation MnxZn1−xFe2O4 (x = 0.5, 0.6, 0.7) were prepared by sol-gel auto combustion method in order to study their structural, elastic and electron magnetic resonance properties. The Bragg reflections in the X-ray diffractograms matched with the formation of cubic spinel phase along with the secondary phases of α-Fe2O3 and Mn2O3. The uneven variation of lattice parameter was found to be depending on the possible cation redistribution in the spinel structure/or grain sizes. From the histograms of SEM studies, the composition x = 0.6 comparatively has a narrow distribution of grain sizes (5–11 μm) than those of compositions x = 0.5 (3.5–8.5 μm) and x = 0.7 (2.5–8.5 μm). The higher and lower vibrational frequencies in the FTIR spectra occurred around 560 cm−1 and 470 cm−1 confirm the cubic spinel phase of present ferrite systems in the line of XRD confirmation. The change in the vibrational frequencies supports the variation of lattice parameter. The variation of lattice energy is supportive for the elastic properties, but not to the structural parameters. The same value of Poisson’s ratio (∼0.35) for the three compositions is an indicative, representing the isotropic behaviour of spinel ferrite systems. The range (2.012–2.106) of Lande’s g-parameter indicates the change in Fe3+–O–Fe3+ superexchange interaction. The results are interpreted based on the possible cation redistribution, the secondary phases presuming the core-shell interactions.

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 Mossbauer 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.

In this study, we report the magnetic properties of nanostructured MnxCe1-xO2 (0 0.1 ≤ x ≤ 0.5) materials, synthesized via microwave refluxing technique. Phase purity of the samples was investigated using the structural characterization techniques such as X-ray diffraction (XRD) and transmission electron microscopy (TEM). These analyses indicated the substitution of Ce-ions with Mn-ions in the lattice. The progressive increase in the oxygen vacancies with increased dopant concentration was demonstrated by Raman, UV–vis and photoluminescence spectroscopic studies. X-ray photoelectron spectroscopy analysis further supported the presence of Mn2+, Ce3+ and Ce4+ ions as well as oxygen vacancies in the samples. The Mn substituted CeO2 nanostructures were found to exhibit room temperature ferromagnetism (RTFM). There was a continuous improvement in the saturation magnetization (MS) values with increased Mn concentration. This might be due to the prevalence of surface oxygen vacancies and the systematic rise in their concentration with increased dopant content.

A thorough knowledge of the effects of land use systems (LUS) on the soil carbon pool and soil total nitrogen (STN) are critical to planning effective strategies for adaptation and mitigation in future scenarios of global climate and land use systems. This study conducted with the objectives of investigating soil carbon, nitrogen storage and carbon management index (CMI) in different LUS under middle Indian Himalayan ecosystem, four LUS: barren land (BL), cultivated land (CL), grass land (GL) and forest land (FL) were selected in Indian mid-Himalaya. A total of 111 composite soil samples [4 treatment (land use systems) 3- soil depths (0–15, 15–30 and 30–45 cm) and 8, 11, 8 and 10 replication for BL, CL, GL and FL systems, respectively] were collected for laboratory analyses. Forest land use system has the highest Walkley-Black Carbon (WBC), total carbon (TC), total nitrogen (TN), carbon and nitrogen (C and N)-storage and CMI values while barren land use system having least amount of WBC, TC, TN, CN-storage and CMI. Land use system had minimum effect on non-labile carbon (NLC), lability of carbon (LC), lability index (LI) and carbon pool index (CPI) of the ecosystem. Moreover, TC and TN were increase in the grass and forest land as compared to barren and cultivated land. The TC concentration was highly correlated with TN (R2 = 0.88, p

The single phase HfxCe1−xO2 (x = 0.01, 0.05 and 0.1) nanoparticles were produced via microwave refluxing technique. The substitution of Hf-ions into CeO2 lattice has been demonstrated by X-ray diffraction and transmission electron microscopy analyses. X-ray photoelectron spectroscopy analysis indicated that Ce was present in + 3 and + 4 states whereas Hf in + 4 state. Raman, UV–Vis and photoluminescence spectroscopic analyses revealed the formation of surface defects including oxygen vacancies in the samples. The estimated defect concentration was 1.09 × 1021, 1.32 × 1021 and 1.49 × 1021 cm−3 for x = 0.01, 0.05 and 0.1 samples respectively. The room temperature ferromagnetic behavior for the samples originate from the surface oxygen vacancies. The prevalence of ferromagnetic clusters considerably raised the MS value for x = 0.05 sample. The augmentation in the MS values with increased Hf concentration could be attributed to the increase in the defect concentration.

Water and nutrient management are major corners in the improvement of productivity and sustainability of rainfed soybean-wheat cropping systems (SWCS). A nine-year-old (2006–2014–15) field experiment was started to explore the effects of recommended dose of farm yard manure (FYM) in SWCS, recommended dose of nitrogen, phosphorus and potassium fertilizers (RDF) along with FYM, FYM + 50% NPK, NPK, FYMsoybean + NPKwheat and without application of NPK and FYM (CK) under rainfed (I0) and supplementary irrigation (I1) situation in SWCS. Results from nine years continuous fertilization of NPK + FYM showed significantly highest grain yield of wheat (2.70 and 3.80 t ha−1) and soybean (2.50 and 2.74 t ha−1) under rainfed (I0) and supplementary irrigation (I1), respectively as compared to rest of treatments. Significant (p

Ce and Dy substituted Cobalt ferrites with the chemical composition CoCe x Dy x Fe 2-2 x O 4 ( x = 0, 0.01, 0.02, 0.03, 0.04, 0.05) were synthesized through the chemical route, citrate-gel auto-combustion method. The structural characterization was carried out with the help of XRD Rieveld analysis, SEM and EDAX analysis. Formation of spinel cubic structure of the ferrites was confirmed by XRD analysis. SEM and EDAX results show that the particles are homogeneous with slight agglomeration without any impurity pickup. The effect of RE ion doping (Ce and Dy) on the dielectric, magnetic and impedance studies was systematically investigated by LCR meter, Vibrating Sample Magnetometer and Impedance analyzer respectively at room temperature in the frequency range of 10 Hz–10 MHz. Various dielectric parameters viz., dielectric constant, dielectric loss and ac conductivity were measured. The dielectric constant of all the ferrite compositions shows normal dielectric dispersion of ferrites with frequency. Impedance analysis confirms that the conduction in present ferrites is majorly due to the grain boundary mechanism. Ferrite sample with x = 0.03 show high dielectric constant, low dielectric loss and hence can be utilized in high frequency electromagnetic devices. Magnetization measurements indicate that with increase in Ce and Dy content in cobalt ferrites, the magnetization values decreased and coercivity has increased.

In this study, we report the effect of Mg-substitution on structural, magnetic and dielectric properties of M-type Sr-Cu hexaferrites (Sr 0.5 Cu 0.5−x Mg x Fe 12 O 19 , x = 0.0, 0.1, 0.2, 0.3, 0.4 and 0.5) prepared by using one step solvent free synthesis technique. Rietveld refinement of X-ray diffraction (XRD) patterns has confirmed the formation of M-type hexaferrite phase. The crystallite size was estimated from XRD lies within the nanometer range. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were also employed to estimate the particle size. TEM micrographs of pure and substituted samples show hexagonal structure with an agglomeration is noticed for x = 0.5. Magnetic interactions were studied by vibrating sample magnetometer (VSM) and Mossbauer spectroscopy technique. VSM results reveal that the values of saturation magnetization ( M S ) increases initially for x = 0.2 Mg-substitution after that decreases drastically from 47.15 emu/g ( x = 0.2) to 1.66 emu/g ( x = 0.5). Similar trend was also observed for remanent magnetization ( M r ) and found to decrease from 17.5 emu/g ( x = 0.2) to 0.3 ( x = 0.5) emu/g. Similarly, the higher value of coercivity ( H C = 1995 Oe) was observed for x = 0.2 sample. Room temperature Mossbauer spectra (MS) were recorded to probe magnetic properties at microscopic level. Five sextets were observed for each sub-lattice. Iron ions were found in Fe 3+ high spin state. The dielectric constant of all samples found to be decreased with increase in the frequency. The dielectric dispersion behaviour was well explained in terms of Maxwell-Wagner polarization in accordance with the Koop's phenomenological theory.

In this study, indium (In3+)-substituted NiCuZn nanostructured ceramic ferrites with a chemical composition of Ni0.5Cu0.25Zn0.25Fe2-xInxO4 (0.0 ≤ x ≤ 0.5) were prepared by chemical synthesis involving sol–gel chemistry. Single phased cubic spinel structure materials were prepared successfully according to X-ray diffraction and transmission electron microscopy analyses. The dielectric properties of the prepared ferrites were measured using an LCR HiTester at temperatures ranging from room temperature to 300 °C at different frequencies from 102 Hz to 5 × 106 Hz. The variations in the dielectric parameters e′ and (tanδ) with temperature demonstrated the frequency- and temperature-dependent characteristics due to electron hopping between the ions. The materials had low dielectric loss values in the high frequency range at all temperatures, which makes them suitable for high frequency microwave applications. A qualitative explanation is provided for the dependences of the dielectric constant and dielectric loss tangent on the frequency, temperature, and composition. Mӧssbauer spectroscopy was employed at room temperature to characterize the magnetic behavior.

The ferrofluids based on ZnxFe3−xO4 (0.01 ≤ x ≤ 0.8) nanoparticles have shown stabilization near therapeutic temperature (∼42 °C) in the presence of external AC magnetic fields similar to that of tetravalent ion substituted magnetites. These nanoparticles were prepared using microwave refluxing technique. Rietveld analysis of X-ray diffraction patterns of the as prepared samples confirmed their single phase mixed spinel type structure. It further suggests that all the Zn2+ ions occupy tetrahedral voids. The spherical shaped particles had sizes in the range of 3–10 nm, as observed under transmission electron microscopy. X-ray photoelectron spectra have confirmed the presence of Fe2+, Fe3+ and Zn2+ ions in the samples. The Zn0.2Fe2.8O4 sample displayed the highest saturation magnetization value (∼65 A m2 kg−1) amongst all the samples. As the concentration of Zn increased, beyond x > 0.3, the value of saturation magnetization continuously diminished due to the dominance of the nonmagnetic ion. Fe2+ ions occupying both the sites was confirmed from room temperature Mossbauer spectroscopy.

Carbon coated LixFePO4 samples with systematically varying Li-content (x = 1, 1.02, 1.05, 1.10) have been synthesized via a sol–gel route. The Li : Fe ratios for the as-synthesized samples is found to vary from ∼0.96 : 1 to 1.16 : 1 as determined by the proton induced gamma emission (PIGE) technique (for Li) and ICP-OES (for Fe). According to Mossbauer spectroscopy, sample Li1.05FePO4 has the highest content (i.e., ∼91.5%) of the actual electroactive phase (viz., crystalline LiFePO4), followed by samples Li1.02FePO4, Li1.1FePO4 and LiFePO4; with the remaining content being primarily Fe-containing impurities, including a conducting FeP phase in samples Li1.02FePO4 and Li1.05FePO4. Electrodes based on sample Li1.05FePO4 show the best electrochemical performance in all aspects, retaining ∼150 mA h g−1 after 100 charge/discharge cycles at C/2, followed by sample Li1.02FePO4 (∼140 mA h g−1), LiFePO4 (∼120 mA h g−1) and Li1.10FePO4 (∼115 mA h g−1). Furthermore, the electrodes based on sample Li1.05FePO4 retain ∼107 mA h g−1 even at a high current density of 5C. Impedance spectra indicate that electrodes based on sample Li1.05FePO4 possess the least charge transfer resistance, plausibly having influence from the compositional aspects. This low charge transfer resistance is partially responsible for the superior electrochemical behavior of that specific composition.

Co-precipitated and 800 °C annealed Ni x Cu 0.1 Zn 0.9- x Fe 2 O 4 ( x = 0.5, 0.6, 0.7) ferrite nano particles were studied by X-ray diffraction, FTIR and FC–ZFC techniques. The presence of Cu 2+ ions drastically affects the cation distribution which was obtained by Rietveld refinement. This cation distribution was utilized in interpreting the structural and magnetic properties. The variation in calculated tetrahedral and octahedral bond lengths ( R A , R B ) and oxygen parameter ( U ) as a function of Ni 2+ ion concentration are explained in terms of cation redistribution given by Rietveld refinement. The variation of tetrahedral and octahedral Fe–O vibrational frequencies observed in FTIR studies are in accordance with the change in R A and R B bond lengths. The metal – oxygen – metal bond angles calculated in the present studies indicates an increase in A – B super exchange interaction as Ni 2+ ion concentration is increased. The variation of blocking temperatures ( T B ) obtained from FC–ZFC studies are in accordance with that expected from Mossbauer studies. The magnetocrystalline anisotropy constant ( K ) calculated from T B values was found to increase as Ni 2+ ion concentration is increased. The K value was found to increase for a given Ni 2+ ion concentration as the temperature is decreased. The coercive field ( H c ) values estimated at 10 K were found to decrease as Ni 2+ ion concentration is increased.

The investigation under study deals with the combustion synthesis of nanocrystalline Mg substituted nickel zinc ferrites i.e., MgxNi0.6−xZn0.4Fe2O4 (x = 0.0 to 0.6) using malic acid dihydrazide as a novel fuel and the effect of magnesium substitution on the structural and magnetic properties. The nanocrystalline monophasic nature of “as prepared” MgxNi0.6−xZn0.4Fe2O4 (x = 0.0 to 0.6) has been confirmed from XRD and Raman spectroscopic studies and the crystallite sizes were found to be in the range of 19–25 nm which nearly matches with TEM. The RT and low temperature magnetization studies indicate a continuous decrease in magnetization with increase in Mg substitution. In contrast, the hysteretic behaviour diminished and the emergence of superparamagnetism is observed in all the samples as the Mg content increases. The decrease in MS with increase in Mg concentration is attributed to the replacement of magnetic Ni2+ ions with non-magnetic Mg2+ ions and also to the enhancement of the Y–K angle by cation redistribution. The variation of AC susceptibility with temperature exhibits broad maxima, indicating a distribution of particle sizes in the sample with the existence of single domain and superparamagnetic type domain structures. The susceptibility decreases continuously beyond x = 0.4 until 0.6, and the samples exhibit only superparamagnetism. The AC susceptibility studies also show a decrease in Curie temperature (TC) with an increase in x for MgxNi0.6−xZn0.4Fe2O4 (x = 0.0 to 0.6) resulting from weakening of A–B interaction. The ZFC–FC studies along with the Mossbauer studies were also corroborated by the proposed existence of dominant superparamagnetism with an increase in Mg concentration.

Prussian blue analogues (PBAs) have recently been synthesized in the form of various heterostructures such as core–shell nanoparticles, layered thin films, and nanosized metal/PBAs for their multifunctional properties. However, herein, we report the synthesis of a nanocomposite CoFe Prussian blue analogue (CoFePBA) molecular magnet with a polyvinylidene fluoride (PVDF) polymer. The cyanide (CN) group of CoFePBAs interacts with the CF2 dipole of PVDF to integrate PBAs uniformly into a PVDF matrix. Interestingly, the composite material exhibits a spontaneous polarization which is mainly due to the formation of the β phase of PVDF. However, the value of electric polarization is observed to be higher (∼0.04 μC cm−2) than the spontaneous electric polarization (∼0.02 μC cm−2) of the bare PVDF. The higher value of electric polarization is attributed to the enhanced dipole–dipole interactions between the fluoride atoms of PVDF and the cyanide (–CN–) ligand of CoFePBAs. Inclusion of PVDF in CoFePBAs not only helps in improving ferroelectricity, but also improves the thermal stability of the CoFePBAs (up to ∼158 °C), in contrast to the bare CoFePBAs, which are stable only up to ∼65 °C.

Single phase equi-atomic (Al0.2Co0.2Fe0.2Mn0.2Ni0.2)3O4 high-entropy oxide (HEO) having spinel structure was synthesised employing simple and cost effective microwave assisted co-precipitation technique, followed by calcination at 500 °C. The material obtained was highly crystalline and stable at higher temperatures. The uniformity in elemental distribution was apprehended through STEM-EDS elemental mapping. The X-ray photoelectron spectroscopy confirmed +3 ionic state for Fe and Al, while other elements oxidised to higher ionic states to maintain charge neutrality. Ferrimagnetic behaviour was confirmed for the obtained HEO through magnetic characterisations.

Recent reports on the magnetic nanoparticles (MNPs) as an efficient and alternative photothermal agent have excited the researchers worldwide. While MNPs have been explored well for high heating performance during magnetic hyperthermia (MHT), their full potential is yet to be explored as an efficient photothermal agent. In addition, the simultaneous exposure of alternating magnetic field (for MHT) and near infrared irradiation (for photothermal therapy PTT) can drastically enhance the heating behaviour of MNPs. In the present work we explored microwave assisted polyol method to get γ-Fe2O3 nanoflowers. The use of sodium acetate in varying amounts, as an alkali source, allowed the modification of structural and magnetic properties leading to the formation of nanoflower with high heating performance during MHT and PTT. Role of defects in γ-Fe2O3 nanoflowers were investigated using photoluminescence spectroscopy which highlighted distinct role of oxygen vacancies and surface states. The nanoflowers with better crystallinity and relatively higher coercive field performed well during MHT. The observed high intrinsic loss power value of 15.21 ± 0.34 nHm2Kg-as significantly higher than the commercially available ferrofluids and previously reported values for nanoflowers. During PTT, the therapeutic temperature of 42 °C was achieved for the aqueous suspension with a concentration as low as 100 µg/mL which demonstrates the superiority of γ-Fe2O3 nanoflowers as an efficient PTT agent.

Co-precipitation method was adopted to obtain zinc ferrite nanoparticles substituted with nickel (0.5 ≤ x ≤ 0.7) followed by sintering at 500 °C for 2 h. The formation of spinel ferrite phase in the present ferrite compositions was confirmed from the X-ray diffractograms. The experimental lattice parameter (a) and average crystallite size ( ) are in between 8.359 - 8.348 A and 12.8 – 14.9 nm. As doping level of Ni2+ increases, an interesting relation was existed in between a and , such that the first one is decreasing and the later one is increasing. The variation of average particle size ( ) from FE-SEM is different from the variation of . The present spinel ferrite Ni0.6Zn0.4Fe2O4 possessed smaller particle size of 17.6 nm. The existence of higher and lower vibrational frequencies in between 579–587 cm−1 and 380–386 cm−1, satisfied the Waldron proposals for the ferrite phase. The variations of elastic moduli are very interesting and tricky when compared to the reported literature. The consistency of Poisson’s ratio for these ferrite compositions, revealed the isotropic behavior of present ferrite systems. The saturation magnetization (MS) at room temperature (RT) has uneven variation and a highest value of 43.2 emu/g was noticed for the composition x = 0.6. The coercivity (HC) at RT is gradually increasing with the doping level of Ni2+ ion incorporation. As temperature is decreasing below the room temperature both the MS and HC are increasing for a particular composition. The blocking temperature (TB) lies in the range of 80–125 K and is increasing with the increase of Ni2+ ion concentration. The findings of the present study were discussed in terms of cation distribution and magnetocrystalline anisotropy presuming core-shell morphology.

M-type hexaferrite PbFe12O19 nano-crystallites with an average diameter of 68 nm are synthesized by high energy ball milling method. The Rietveld refinement of the X-ray diffraction (XRD) pattern has confirmed the single-phase magnetoplumbite (M) structure of the sample with the space group P63/mmc. Surface morphology is analyzed using transmission and field emission scanning electron microscopes (TEM and FE-SEM). Dielectric studies revealed ferro- to antiferro- and antiferro- to paraelectric transitions. Initial permeability is found to be invariant with temperature and frequency. Small polaron hopping is found to be the prominent conduction mechanism. The room temperature Mossbauer spectrum showed a superposition of five sextets (Zeeman splitting patterns) associated with the five sites of the iron ions, which are ferric (Fe3+) state. The values of the hyperfine magnetic fields are found to be 51.12, 50.8, 48.95, 41.15, and 40.11 Tesla corresponding to the 4f2↓, 2a↑, 4f1↓, 12 k↑, and 2b↑ sites, respectively.

Biological and ecological changes across the Paleogene hyperthermal events were accompanied by dramatic shifts in sedimentation systems in both marine and continental environments. This study investigates the formation of authigenic glauconite within a biostratigraphically constrained section encompassing the Paleocene-Eocene Thermal Maximum (PETM). Paleogene transgressive shelf deposits in the Jaisalmer Basin in western India are represented by the Khuiala Formation, consisting of grey shale, limestone, and glauconitic shale. Foraminiferal assemblage not only constrains the age of the glauconitic shale to planktic zone E1 but also indicates the deposition of sediments in an oxygen-depleted mid-shelf environment. A detailed geochemical and mineralogical characterization of the authigenic glauconite within the mid-shelf deposits reveals the highest glauconite content within the maximum flooding zone, immediately below the negative carbon isotope excursion representing the PETM, followed by its steady decrease. The geochemical signature of the glauconite is unusual for its high Al2O3 and MgO and medium Fe2O3 and SiO2 contents. The K2O content suggests the ‘evolved’ nature of the glauconite, which is confirmed by the X-ray diffractional parameters and the presence of the ‘rosette’ texture in FEG-SEM images. The glauconite evolved by Al-for-Fe substitution in the octahedral site and subsequent fixation of K+ into the interlayer sites. The high alumina content of the glauconite corresponds to the high Al3+ in the tetrahedral layer, inherited from an aluminous substrate. Mossbauer spectroscopy suggests the dominance of Fe3+ compared to Fe2+ in the octahedral site of glauconite pellets. The unusual variety of glauconite formed by the transformation of continent-derived kaolinite and iron oxide in oxygen-depleted porewater conditions. Glauconite authigenesis in the Khuiala Formation is strongly influenced by the warm climatic condition, oxygen-depletion in the mid-shelf environment, and sharp marine transgression promoting sediment starvation associated with the PETM.

The inverse spinel lithium ferrite compound LixFe5O8 has attracted a lot of attention because of its highest magnetoelectric coupling temperature. Here, we have investigated the effect of Lithium substitution on the structural and magnetic properties of ordered LixFe5O8−y (x = 0.91 and 1.02) using the X-ray diffraction, Mossbauer spectroscopy, dc magnetization, and neutron diffraction techniques. The Rietveld refinement of X-ray diffraction patterns confirms single phase formation of these compounds in cubic structure (space group P4332). Lithium composition for both compounds was determined using the atomic emission spectrometry (ICP-AES) measurements. The Rietveld refinement of neutron diffraction patterns reveal that both compounds order in a ferrimagnetic structure, where the magnetic moments of iron at the octahedral (12d) and tetrahedral (8c) sites are aligned anti-parallel. The refined values of the ordered moments for Fe3+ ions at 12d (octahedral) and 8c (tetrahedral) sites are 4.185 µB and 4.545 µB, respectively, for x = 0.91; and the corresponding values for x=1.02 are 4.950 µB and 5.274 µB, respectively. An increase in the value of saturation magnetization (in the M vs H study) has been observed with the increasing concentration of the Li. The observed values of the saturation magnetization at 5, 50, 100, 200 and 300 K are 3.91, 3.88, 3.85, 3.76, and 3.51 μB per f.u. for x=0.91 whereas for x=1.02 the corresponding values are 4.76, 4.70, 4.68, 4.56 and 4.33 μB per f.u. The observed increase in the saturation magnetization and ordered moment with increasing the Li concentration has been ascribed to the presence of iron (~9%) at the lithium site (4b) and similar amount of iron vacancies at 12d (octahedral) and 8c (tetrahedral) sites, for the x = 0.91 compound. Our results show that the magnetic properties of these compounds are tunable. The ferrimagnetic order determined using the microscopic neutron diffraction technique in the present study will provide a new pathway to build theoretical models for the magnetoelectric coupling.

Through our previous studies it was established that non- precious Fe2O3 based catalyst has the potential to replace Pt based catalyst for high temperature sulfuric acid decomposition, the energy conversion step in iodine- sulfur or hybrid-sulfur thermochemical cycles for water splitting (Banerjee et al. [11] and [25]). However, issues like agglomeration and grain growth during prolonged operation still remain to be fully resolved. With an aim to develop low cost, abundant transition metal oxide catalyst with high activity and stability, Fe2O3 nanoparticles immobilized on SiO2 support is explored, anticipating that the Fe2O3-SiO2 interactions may prevent self agglomeration of Fe2O3 nanoparticles. Several catalysts with varying Fe2O3 content ranging from 5 to 20 wt% were synthesized, characterized and their catalytic activity evaluated. Structural investigations by XRD and Mossbauer spectroscopy revealed that the 1000 °C calcined samples contained e-Fe2O3 as the major phase in addition to minor α and γ-Fe2O3 phases. e-Fe2O3 were found to be dispersed as nanorods with typical width of 5 nm from HRTEM images. Analysis of surface features by N2-BET surface area, pore size distribution, pore volume and XPS indicated that the majority of Fe2O3 was encapsulated within the mesoporous structure of SiO2 upto 15 wt.%, beyond which Fe2O3 was deposited outside the porous network in an enhanced quantity. The surface area of Fe2O3(15 wt.%)/SiO2 was found to be 99.6 m2/g. Presence of Fe-O-Si linkages was confirmed by XPS, and supported by successive TPR/TPO studies. The extent of reducibility measured via TPR increased with increasing loading and was found to be maximum for the 15 wt.% dispersed samples. The catalytic activity was found to increase with an increase in loading of active Fe2O3 content upto a SO2 yield of ∼ 92% at 900 °C at a WHSV of 27 g acid g−1 h−1, for 15 wt.% and then decreased. Further evaluation of the 15 wt.% sample revealed the durability (100 h) and practical applicability of the composition. The surface morphology, structure and composition underwent modifications during the 100 h operation in order to adapt to the reaction environment (high temperature, steam, oxides of sulfur) and the Fe2O3 (15 wt.%)/SiO2 catalyst exhibited iron sulfate formation and significant surface reorganization. The high catalytic activity can be ascribed to nanoparticulate nature of Fe2O3 and stability due to its anchored structure on SiO2. These findings would inspire the design of active and stable catalyst for high temperature catalytic reactions.