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In this study LiFePO4/C composite particles were synthesized using five different carbon sources via a one-step sol-gel method. La-doped LiFePO4 was also synthesized using the sol-gel method. The XRD pattern of LixLayFePO4 (x = 0.9~1.0, y = 0~0.1) after being calcined at 700 °C for 10 h indicates that as the doping ratio increased, the sample's cell volume first increased then decreased, reaching a maximum value of 293.36 Å3 (x = 0.94, y = 0.06). The XRD patterns of Li0.92La0.08FePO4 after being calcined at different temperatures for 10 h indicate that with increasing calcination temperature, the (311) diffraction peak drifted toward a smaller diffraction angle. Similarly, the XRD patterns of Li0.92La0.08FePO4 after being calcined at 700 °C for different durations indicate that with increasing calcination times, the (311) diffraction peak drifted toward a larger diffraction angle. The infrared spectrum pattern of LixLayFePO4 (x = 0.9~1.0, y = 0~0.1) after being calcined at 700 °C for 10 h shows absorption peaks corresponding to the vibrations of the Li–O bond and PO43- group. An SEM analysis of LixLayFePO4 (x = 1, y = 0; x = 0.96, y = 0.04; x = 0.92, y = 0.08) after being calcined at 700 °C for 10 h indicates that the particles were irregular in shape and of uniform size. The hysteresis loops of Li0.92La0.08FePO4 after being calcined at 600 °C, 700 °C, or 800 °C for 10 h indicate that with increasing calcination temperature, the Ms gradually increased, while the Mr and Hc decreased, with minimum values of 0.08 emu/g and 58.21 Oe, respectively. The Mössbauer spectra of LixLayFePO4 (x = 1, y = 0; x = 0.96, y = 0.04; x = 0.92, y = 0.08) after being calcined at 700 °C for 10 h indicate that all samples contained Doublet(1) and Doublet(2) peaks, dominated by Fe2+ compounds. The proportions of Fe2+ were 85.5% (x = 1, y = 0), 89.9% (x = 0.96, y = 0.04), and 96.0% (x = 0.92, y = 0.08). The maximum IS and QS of Doublet(1) for the three samples were 1.224 mm/s and 2.956 mm/s, respectively. [ABSTRACT FROM AUTHOR]

The syntheses, coordination chemistry, and Mössbauer spectroscopy of hepta-iron(III) complexes using derivatised salicylaldoxime ligands from two categories; namely, 'single-headed' (H2L) and 'double-headed' (H4L) salicylaldoximes are described. All compounds presented here share a [Fe3-µ3-O] core in which the iron(III) ions are µ3-hydroxo-bridged in the complex C1 and µ3-oxo-bridged in C2 and C3. Each compound consists of 2 × [Fe3-µ3-O] triads that are linked via a central [Fe(µ2-OH)6]3- ion. In addition to the charge balance and microanalytical evidence, Mössbauer measurements support the fact that the triads in C1 are µ3-OH bridged and are µ3-O bridged in C2 and C3. [ABSTRACT FROM AUTHOR]

Two novel isostructural cyanide‐bridged hexadecanuclear complexes with the general formula {[Fe(CN)6]6[M{en(Bn)py}]10}2+ [M=Fe (12+), Ni (22+)] have been synthesized. The structural analyses disclose the presence of multivalent Fe centres with different spin states in complex 12+ whereas all the Fe centres share a conserved oxidation state in complex 22+. The DC magnetic study revealed antiferromagnetic interactions between the adjacent metal centres and ferrimagnetic behaviour in 12+. On the other hand, ferromagnetic interactions were observed in complex 22+ due to nearly orthogonal orientation of the interacting orbitals and poor spatial overlap as observed in BS‐DFT calculations. [ABSTRACT FROM AUTHOR]

Coordination compounds, like iron(II) triazole complexes, exhibit spin crossover (SCO) behavior at around room temperature. Therefore, they are interesting for a variety of possible applications, and it is convenient to integrate them into polymers. Due to a reduction of the iron content and thus also 57Fe content in the sample through integration in polymers, Mössbauer measurements are only possible with greater difficulty or very long measurement times without expensive enrichment of the samples with 57Fe. So, other ways of improving the Mössbauer signal for these composite materials are necessary. Therefore, we pressed these composite materials to improve the Mössbauer spectra. In this study, we synthesized an iron(II) triazole spin crossover complex and an electrospun polymer complex composite nanofiber material including the same complex. For both products, Mössbauer measurements were performed at room temperature before and after using a press to show that the complex composite is not harmed through pressing. We investigate the influence of the pressing impact on the Mössbauer measurements in the context of measurement statistics and the measured signals. We show that pressing is not connected to any changes in the sample regarding the spin and oxidation state. We present that pressing improves the statistics of the Mössbauer measurements significantly. Furthermore, we use SEM measurements and PXRD to investigate whether or not the obtained fiber mats are destroyed in the pressing process. [ABSTRACT FROM AUTHOR]

Compounds that exhibit the spin crossover effect are known to show a change of spin states through external stimuli. This reversible switching of spin states is accompanied by a change of the properties of the compound. Complexes, like iron (II)-triazole complexes, that exhibit this behavior at ambient temperature are often discussed for potential applications. In previous studies we synthesized iron (II)-triazole complexes and implemented them into electrospun nanofibers. We used Mössbauer spectroscopy in first studies to prove a successful implementation with maintaining spin crossover properties. Further studies from us showed that it is possible to use different electrospinning methods to either do a implementation or a deposition of the synthesized solid SCO material into or onto the polymer nanofibers. We now used a solvent in which both, the used iron (II)-triazole complex [Fe(atrz)3](2 ns)2 and three different polymers (Polyacrylonitrile, Polymethylmethacrylate and Polyvinylpyrrolidone), are soluble. This shall lead to a higher homogeneous distribution of the complex along the nanofibers. Mössbauer spectroscopy and other measurements are therefore in use to show a successful implementation without any significant changes to the complex. [ABSTRACT FROM AUTHOR]

Two trinuclear oxo-centred iron(III) coordination compounds of monensic and salinomycinic acids (HL) were synthesized and their spectral properties were studied using physicochemical/thermal methods (FT–IR, TG–DTA, TG–MS, EPR, Mössbauer spectroscopy, powder XRD) and elemental analysis. The data suggested the formation of [Fe3(µ3–O)L3(OH)4] and the probable complex structures were modelled using the DFT method. The computed spectral parameters of the optimized constructs were compared to the experimentally measured ones. In each complex, three metal centres were joined together at the axial position by a μ3–O unit to form a {Fe3O}7+ core. The antibiotics monoanions served as bidentate ligands through the carboxylate and hydroxyl groups located at the termini. The carboxylate moieties played a dual role bridging each two metal centres. Hydroxide anions secured the overall neutral character of the coordination species. Mössbauer spectra displayed asymmetric quadrupole doublets that were consistent with the existence of two types of high-spin iron(III) sites with different environments—two Fe[O5] and one Fe[O6] centres. The solid-state EPR studies confirmed the +3 oxidation state of iron with a total spin St = 5/2 per trinuclear cluster. The studied complexes are the first iron(III) coordination compounds of monensin and salinomycin reported so far. [ABSTRACT FROM AUTHOR]

Nanoparticles of cobalt ferrite are doped with multiple lanthanum (La) amounts up to an unusually high level of doping. They are synthesised using a soft chemical approach. The structural characterisation is conducted using X-ray diffraction (XRD) and transmission electron microscopy (TEM). The crystallite size, micro strain, crystal density, deformation and twin fault probability are found out by Rietveld analysis. Room temperature Mössbauer spectroscopy is performed for determination of spin aberration due to La doping. The values of isomeric shift are obtained in the range of 0.33–0.41 mm/s for different samples as compared to the standard range of 0.32–0.34 mm/s. Large and narrow hysteresis are observed in 5 K and 300 K magnetic measurements, respectively with coercivities in the range 0.2–2 kOe at room temperature. The coercivity is in the range of 0.8–15 kOe at 5 K. The results from magnetic measurement show deviation from standard which is also seen from the inferences from Photoluminescence (PL) which hint at the increased versatility of the ferrite material by doping with rare earth (RE) metals. However, there is an upper limit to this inclusion in the ferrite matrix. As such there is also the existence of wasp-waist hysteresis which is indicative of antiferromagnetic (AFM) to ferromagnetic (FM) interaction but from the Rietveld analysis it is seen that this coupling does not have an undesirable effect on the stability of the nanoferrite. [ABSTRACT FROM AUTHOR]

Nickel ferrite nanoparticles doped with zinc were synthesized at a lower reaction temperature of 180 °C. The research delved into their structural, optical, dielectric, and magnetic properties. These nanoparticles exhibited a distinct cubic spinel structure, with crystallite sizes ranging from 33 to 51 nm. FTIR analysis revealed metal oxide stretching vibrations between 400–600 nm. FESEM and HR-TEM examinations unveiled irregularly shaped nano-particles. XPS analysis disclosed the chemical states of Zn2+, Fe3+, and Ni2+ ions. Mossbauer spectra exhibited two sextet patterns related to tetrahedral (A) and octahedral (B) sites, plus a weak doublet pattern. Magnetic tests showed a decrease in saturation magnetization (Ms) but an increase in remanent magnetization (Mr) and coercivity (Hc) values upon doping.

In this study LiFePO4/C composite particles were synthesized using five different carbon sources via a one-step sol-gel method. La-doped LiFePO4 was also synthesized using the sol-gel method. The XRD pattern of LixLayFePO4 (x = 0.9~1.0, y = 0~0.1) after being calcined at 700 °C for 10 h indicates that as the doping ratio increased, the sample’s cell volume first increased then decreased, reaching a maximum value of 293.36 Å3 (x = 0.94, y = 0.06). The XRD patterns of Li0.92La0.08FePO4 after being calcined at different temperatures for 10 h indicate that with increasing calcination temperature, the (311) diffraction peak drifted toward a smaller diffraction angle. Similarly, the XRD patterns of Li0.92La0.08FePO4 after being calcined at 700 °C for different durations indicate that with increasing calcination times, the (311) diffraction peak drifted toward a larger diffraction angle. The infrared spectrum pattern of LixLayFePO4 (x = 0.9~1.0, y = 0~0.1) after being calcined at 700 °C for 10 h shows absorption peaks corresponding to the vibrations of the Li–O bond and PO43- group. An SEM analysis of LixLayFePO4 (x = 1, y = 0; x = 0.96, y = 0.04; x = 0.92, y = 0.08) after being calcined at 700 °C for 10 h indicates that the particles were irregular in shape and of uniform size. The hysteresis loops of Li0.92La0.08FePO4 after being calcined at 600 °C, 700 °C, or 800 °C for 10 h indicate that with increasing calcination temperature, the Ms gradually increased, while the Mr and Hc decreased, with minimum values of 0.08 emu/g and 58.21 Oe, respectively. The Mössbauer spectra of LixLayFePO4 (x = 1, y = 0; x = 0.96, y = 0.04; x = 0.92, y = 0.08) after being calcined at 700 °C for 10 h indicate that all samples contained Doublet(1) and Doublet(2) peaks, dominated by Fe2+ compounds. The proportions of Fe2+ were 85.5% (x = 1, y = 0), 89.9% (x = 0.96, y = 0.04), and 96.0% (x = 0.92, y = 0.08). The maximum IS and QS of Doublet(1) for the three samples were 1.224 mm/s and 2.956 mm/s, respectively.

The syntheses, coordination chemistry, and Mössbauer spectroscopy of hepta-iron(III) complexes using derivatised salicylaldoxime ligands from two categories; namely, ‘single-headed’ (H2L) and ‘double-headed’ (H4L) salicylaldoximes are described. All compounds presented here share a [Fe3-µ3-O] core in which the iron(III) ions are µ3-hydroxo-bridged in the complex C1 and µ3-oxo-bridged in C2 and C3. Each compound consists of 2 × [Fe3-µ3-O] triads that are linked via a central [Fe(µ2-OH)6]3− ion. In addition to the charge balance and microanalytical evidence, Mössbauer measurements support the fact that the triads in C1 are µ3-OH bridged and are µ3-O bridged in C2 and C3.

The main aims of this work were the synthesis and characterization of iron(III) complexes with a ditopic ligand H2L consisting of a bis(salicylidene) isothiosemicarbazide moiety with a N2O2 binding site and a crown-ether (O6) moiety. A series of high-spin iron(III) complexes, i.e., [FeIIILClBa(CH3OH)(H2O)0.5(ZnCl4)] (1), [FeIIILCl] (2), [FeIIIL(N3)] (3) and [(FeIIIL)2O] (4), were synthesized. The complexes were characterized by mass spectrometry, IR and UV--Vis spectroscopy, variable temperature (VT) magnetic susceptibility measurements, Mössbauer spectroscopy, single crystal X-ray diffraction and cyclic voltammetry. [ABSTRACT FROM AUTHOR]

Ni0.65Zn0.35AlxFe2−xO4 that has been synthesized using a solution-gelation method and calcined at 600 °C for 4 h was characterized using X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). A single-phase cubic spinel structure belonging to the Fd-3 m space group was confirmed by Rietveld refinement. The cation distribution that was anticipated using the XRD data deviated from the preferential occupancy, and the results of the magnetization analysis supported this. The two absorption bands in the FTIR spectra corresponding to the tetrahedral and octahedral sites further support the establishment of the ferrite skeleton. Al3+ doping was found to have a considerable impact on the Debye temperature, bulk modulus, and stiffness modulus measured using FTIR data. Interatomic bonding became stronger, increasing elastic moduli. The morphology was examined using SEM, whose results showed a cluster of grains. Additionally, spherical nanoparticles with an average size of 28 nm were visible in the TEM image, which is in good agreement with the crystallite size given by the Williamson-Hall method. The Mössbauer analysis and M–H data showed a soft magnetic behavior with coercivity fluctuation. According to Arrhenius plots, all samples displayed a semiconducting characteristic. With Al3+ doping, dielectric studies revealed a declining trend. [ABSTRACT FROM AUTHOR]

In this study, we give a thorough evaluation of the structural, magnetic, and magnetocaloric properties in iron-rich PrFe 11 Ti intermetallic alloy with ThMn 12 -type structure using a combination of experimental and theoretical analysis. X-ray diffraction coupled with Rietveld refinement was used to characterize the structure, which revealed a unique tetragonal crystal structure with I 4 / m m m space group. The 8 i site was identified as the preferred site for the Ti atom. This finding was confirmed by various techniques, including XRD, DFT, and Mössbauer spectrometry. Magnetic properties were studied through intrinsic magnetic measurements and magnetocaloric effect analysis. Mössbauer spectroscopy was employed to probe the local magnetic environment and for further characterization of the material's magnetic properties. The experimental results were complemented by theoretical calculations based on density functional theory (DFT). A promising magnetocaloric effect is observed, with a significant maximum magnetic entropy ( − Δ S M max = 2.5 J·kg − 1 ·K − 1 ) and a relative cooling power about 70 J·kg − 1 under low magnetic field change μ 0 Δ H = 1.5 T. Overall, our results provide a deeper understanding of the structural and magnetic properties of the material under study and demonstrate the effectiveness of the combined experimental and theoretical approach in the investigation of complex materials. The insights gained from this study could have implications for the development of advanced magnetic materials with enhanced properties for potential magnetic applications. [ABSTRACT FROM AUTHOR]

The solid-state reaction technique was used to produce polycrystalline Bi1−xBaxFe1−x(Zn1/3Nb2/3)xO3 at different substitutions for x = 0, 0.025 and 0.05 (referred to as BFO, BBFZN25, and BBFZN50, respectively). Both x-ray diffraction and Raman spectroscopy revealed that the substitution did not affect the rhombohedral structure of BFO. However, the substitution did not prevent the formation of a second phase, which was identified as Bi25FeO39. The amount of this impurity phase was extracted through Rietveld refinement and was further corroborated by Mössbauer spectroscopy. Lattice parameters were found to be increased owing to substitution of larger ions on average. The substitution not only had an impact on average crystallite size, microstrain and dislocation density of BFO, but also had a significant effect on its dielectric properties. As a result, the dielectric permittivity was enhanced, with a notable reduction in dielectric loss. In particular, the magnitude of dielectric permittivity for the optimal composition BBFZN25 reached a value of 360 at room temperature (RT), which is much greater than that for pure BFO. This higher dielectric constant may be attributable to the larger average crystallite size. The reduction in dielectric loss, at RT, suggests an improvement in the electrical resistivity of BFO, caused by the reduction of the creation of oxygen vacancies and the generation of Fe2+. The non-formation of Fe2+ was verified through Mössbauer spectroscopy. The remarkable increase in the dielectric constant for BBFZN25 at higher temperatures (T > RT) is attributed to the interfacial polarization occurring at grain–grain boundary and internal barrier layers related to the Bi25FeO39 phase. [ABSTRACT FROM AUTHOR]

The direct oxidation of methane to methanol (MTM) is a significant challenge in catalysis and holds profound economic implications for the modern chemical industry. Bioinspired metal–organic frameworks (MOFs) with active iron and copper sites have emerged as innovative catalytic platforms capable of facilitating MTM conversion under mild conditions. This review discusses the current state of the art in applying MOFs with iron and copper catalytic centers to effectuate the MTM reaction, with a focus on the diverse spectroscopic techniques employed to uncover the electronic and structural properties of MOF catalysts at a microscopic level. We explore the synthetic strategies employed to incorporate iron and copper sites into various MOF topologies and explore the efficiency and selectivity of the MOFs embedded with iron and copper in acting as catalysts, as well as the ensuing MTM reaction mechanisms based on spectroscopic characterizations supported by theory. In particular, we show how integrating complementary spectroscopic tools that probe varying regions of the electromagnetic spectrum can be exceptionally conducive to achieving a comprehensive understanding of the crucial reaction pathways and intermediates. Finally, we provide a critical perspective on future directions to advance the use of MOFs to accomplish the MTM reaction. [ABSTRACT FROM AUTHOR]

Coordination compounds, like iron(II) triazole complexes, exhibit spin crossover (SCO) behavior at around room temperature. Therefore, they are interesting for a variety of possible applications, and it is convenient to integrate them into polymers. Due to a reduction of the iron content and thus also 57Fe content in the sample through integration in polymers, Mössbauer measurements are only possible with greater difficulty or very long measurement times without expensive enrichment of the samples with 57Fe. So, other ways of improving the Mössbauer signal for these composite materials are necessary. Therefore, we pressed these composite materials to improve the Mössbauer spectra. In this study, we synthesized an iron(II) triazole spin crossover complex and an electrospun polymer complex composite nanofiber material including the same complex. For both products, Mössbauer measurements were performed at room temperature before and after using a press to show that the complex composite is not harmed through pressing. We investigate the influence of the pressing impact on the Mössbauer measurements in the context of measurement statistics and the measured signals. We show that pressing is not connected to any changes in the sample regarding the spin and oxidation state. We present that pressing improves the statistics of the Mössbauer measurements significantly. Furthermore, we use SEM measurements and PXRD to investigate whether or not the obtained fiber mats are destroyed in the pressing process.

Magnetic Functional Nanomaterials Co1−yZnyRExFe2−xO4 (RE (rare-earth) = La,Sm,Gd) were prepared using the sol–gel combustion method. XRD characterization confirms that the ferrite samples we synthesized are single-phase cubic structures. The variation in the average crystalline size and lattice parameter is related to RE ion doping. The Mössbauer spectra of CoRExFe2−xO4 are two sets of magnetic six-wire peaks that indicate the ferrimagnetic behavior of the sample. The calcination temperature greatly influences the absorption area of Mössbauer for CoFe2O4, indicating that the calcination temperature affects the iron ion content at the octahedral B and tetrahedral A sites. Additionally, scanning electron microscopy measurements of the substituted specimens reveal that the ferrite powders are nanoparticles. With an increase in RE ions, the coercivity increases, and the saturation magnetization changes obviously. The XRD characterization of Co0.7Zn0.3LaxFe2−xO4 shows that the main crystalline phase of the sample is the cubic spinel structure phase, and there are fewer secondary crystalline phases. The lattice parameter tends to decrease with the substitution of La3+ ions. The average grain size decreased significantly with the increase in La content. From ferrimagnetic state transition to relaxation behavior, the hyperfine magnetic field decreases in La concentration by room temperature Mössbauer spectra. With the substitution of La3+ ions, both the saturation magnetization and coercivity of the samples were reduced, and the coercivity of all samples was lower. [ABSTRACT FROM AUTHOR]

The effect of thermal treatment on the structural arrangement and pore size distribution in NiFe2O4/reduced graphene oxide composite materials has been studied using X-ray diffraction, Mössbauer spectroscopy, and nitrogen adsorption/desorption technique. Composite materials have been successfully synthesized by the joint hydrothermal method using graphene oxide colloidal solution obtained by the modified Tour method. The electrical properties of the composite materials, as well as the pure component, have been studied in the frequency range from 0.1 Hz to 1 MHz, in the temperature range from 25 to 175 °C using impedance spectroscopy. A synergetic increase in the electrical conductivity of composite materials compared to pure components has been observed. The activation energies of interparticle hopping of charge carriers have been calculated using Arrhenius-type conductivity plots. [ABSTRACT FROM AUTHOR]

Two trinuclear oxo-centred iron(III) coordination compounds of monensic and salinomycinic acids (HL) were synthesized and their spectral properties were studied using physicochemical/thermal methods (FT–IR, TG–DTA, TG–MS, EPR, Mössbauer spectroscopy, powder XRD) and elemental analysis. The data suggested the formation of [Fe3(µ3–O)L3(OH)4] and the probable complex structures were modelled using the DFT method. The computed spectral parameters of the optimized constructs were compared to the experimentally measured ones. In each complex, three metal centres were joined together at the axial position by a μ3–O unit to form a {Fe3O}7+ core. The antibiotics monoanions served as bidentate ligands through the carboxylate and hydroxyl groups located at the termini. The carboxylate moieties played a dual role bridging each two metal centres. Hydroxide anions secured the overall neutral character of the coordination species. Mössbauer spectra displayed asymmetric quadrupole doublets that were consistent with the existence of two types of high-spin iron(III) sites with different environments—two Fe[O5] and one Fe[O6] centres. The solid-state EPR studies confirmed the +3 oxidation state of iron with a total spin St = 5/2 per trinuclear cluster. The studied complexes are the first iron(III) coordination compounds of monensin and salinomycin reported so far.

La 0. 8 Sr 0. 2 Fe 1 − x Mn x O 3 (x = 0. 0 , 0.1, 0.3 and 0.5) series samples were prepared by sol–gel method and characterized by powder X-ray diffractometer (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and Mössbauer spectroscopy. The effects of Mn doping on the microstructure, morphology and electronic structure of La–Sr ferrite were investigated. The XRD results show that all samples are single phase and have orthorhombic structures with Pbnm space group. The surface morphology and composition of chemical elements of the samples were analyzed by SEM and EDS, and the experimental values were consistent with the expected values. The sample was tested by 5 7 Fe Mössbauer spectroscopy at room temperature, and the results showed that the percentage of doublet increased gradually with the increase of Mn ion doping ratio, and at x = 0. 5 , all the sextet disappeared and only the doublet existed. According to the analysis, it can be seen that the prepared series of samples underwent a transition from antiferromagnetic to paramagnetic. La0.8Sr0.2Fe1–xMnxO3 (x = 0.0, 0.1, 0.3 and 0.5) series samples were prepared by sol–gel method, and the effect of Mn3+ doping on the structural morphology and electronic structure of La–Sr ferrite was studied. Mössbauer spectrum test results show that with the increase in the doping ratio of Mn3+, the percentage of double peaks gradually increases. When x = 0.5, all the sextet disappeared and only the doublet existed. The analysis shows that Mn3+ doping led to the transition of La–Sr ferrite from antiferromagnetic to paramagnetic. [ABSTRACT FROM AUTHOR]

AyB1−yCxFe2−xO4 (C=Ho,Gd,Al) ferrite powders have been synthesized by the sol-gel combustion route. The X-ray diffraction of the CoHoxFe2−xO4 (x = 0~0.08) results indicated the compositions of single-phase cubic ferrites. The saturation magnetisation of CoHoxFe2−xO4 decreased by the Ho3+ ions, and the coercivity increased initially and then decreased with the increase of the calcination temperature. The Mössbauer spectra indicated that CoHoxFe2−xO4 displays a ferrimagnetic behaviour with two normal split Zeeman sextets. The magnetic hyperfine field tends to decrease by Ho3+ substitution owing to the decrease of the A–B super-exchange by the paramagnetic rare earth Ho3+ ions. The value of the quadrupole shift was very small in the CoHoxFe2−xO4 specimens, indicating that the symmetry of the electric field around the nucleus is good in the cobalt ferrites. The absorption area of the Mössbauer spectra changed with increasing Ho3+ substitution, indicating that the substitution influences the fraction of iron ions at tetrahedral A and octahedral B sites. The X-ray diffraction of Mg0.5Zn0.5CxFe2−xO4(C=Gd,Al) results confirmed the compositions of single-phase cubic ferrites. The variation of the average crystalline size and lattice constant are related to the doping of gadolinium ions and aluminum ions. With increasing gadolinium ions and aluminum ions, the coercivity increased and the saturation magnetization underwent a significant change. The saturation magnetization of AlMg0.5Zn0.5FeO4 ferrite reached a minimum value (MS= 1.94 mu/g). The sample exhibited ferrimagnetic and paramagnetic character with the replacement with Gd3+ ions, that sample exhibited paramagnetic character with the replacement with Al3+ ions, and the isomer shift values indicated that iron is in the form of Fe3+ ions. [ABSTRACT FROM AUTHOR]

Herein, the effects of different Sr content doping on the crystal structure and electronic structure of La1−xSrxFeO3−δ (LSFO‐x, x = 0, 0.2, 0.5, 0.8, 1.0) are studied by X‐ray diffraction (XRD) and Mössbauer spectroscopy. It is shown in the XRD results that the structure of LSFO‐x changes from orthorhombic (Pnma [#62]) to cubic (Pm‐3m (#221)) to tetragonal (I4/mmm (#139)) with increasing strontium doping. It is shown in Mössbauer spectrum analysis that with the gradual increase of Sr doping, iron ions finally change from +3 oxidation state to +4 oxidation state after passing through an intermediate oxidation state of +3.5. The Fe3.5+ state can result from rapid electron exchange (Fe3+ + Fe4+ ⇋ Fe4+ + Fe3+) between iron ions of different oxidation states within the crystal structure; the study provides some reference for future research to study the effect of iron‐oxidation state on the specific activity of strontium‐doped LaFeO3. [ABSTRACT FROM AUTHOR]

We explore the solventless synthesis of iron oxide nanomaterials obtained on thermal conversion of iron(III)citrate in presence of malonic acid and glucose as co-precursors in varying weight ratios and physical characterization of the materials obtained. Pure phase of hematite was found only for a particular combination of precursor and co-precursor and else a mixture of hematite and magnetite. Significant effect of the co-precursors on the nature and size of the synthesized materials was noticed. Gradual conversion of hematite to magnetite with increasing amount of co-precursor was established. Morin transition was observed in the temperature dependent magnetization study for the hematite materials. Absorption spectroscopy exhibited three different electronic transitions that take place within the 3d5 shell of the octahedrally coordinated Fe3+ ions for hematite materials. The optical (direct and indirect) band gaps estimated from the Tauc's plot showed particle size dependence. From photoluminescence study the transitions of trapped electrons in various defect states of oxygen vacancies were observed which led to the appearance of nonradiative peaks. In the Raman spectra the significant bands of hematite (A1g and Eg bands) were noted. From morphology study the hematite nanomaterials appear as clusters of large irregular shaped particles of various sizes. Formation of hematite nanomaterials as observed by XRD studies was supplemented by the SAED patterns obtained in the HRTEM study. Present study established that nano-sized pure hematite materials can be thermally synthesized at comparatively lower temperature on thermal decomposition of iron(III)citrate by varying the weight ratio of suitable co-precursors. [ABSTRACT FROM AUTHOR]

Different doping elements have been used to enhance the dielectric properties of BaTiO3 ceramic. In this work, the effect of substitution of Ba by Bi in A site and Ti by Fe in B site on structural, dielectric and electrical properties of Ba1-xBixTi0.80Fe0·20O3 ceramics at (x = 0.00, 0.05, 0.10 and 0.15) was investigated by X-ray diffraction, Raman spectroscopy, Scanning Electron Microscopy (SEM), Mössbauer spectroscopy as well as dielectric measurements. The Rietveld refinement results revealed that the prepared compounds crystallize in both tetragonal (P4mm) and hexagonal (P63/mmc) phases for x = 0.00 and 0.05 while at x = 0.10 and 0.15, the hexagonal phase disappears and only the tetragonal phase is fitted. The Raman spectra confirmed the disappearance of hexagonal phase in benefit of tetragonal phase as the Bi3+ substitution increases. Based on Mössbauer analyses results, all the samples are in paramagnetic state at room temperature and the Fe is oxidized under Fe3+ without the presence of Fe2+ or Fe4+ ions. The dielectric measurements as function of temperature are studied and tree broad and relaxor phase transitions were detected: from rhombohedral to orthorhombic phase TR-O and to tetragonal ferroelectric phase TO-T then to cubic paraelectric phase Tm. These phase transitions were displaced to the lower temperature with increasing of Bi3+ substitution. The values of ε′r increase gradually with increasing of Bi3+contents which confirmed the enhancement of dielectric properties of BaTi0·80Fe0·20O3 by Bi substitution on Ba site. The diffuse phase transitions were described by fitting the modified Uchino relation. The Cole–Cole analyses showed that both the grain and grain boundaries resistivity values are higher for Bi3+ substituted samples which are responsible to the dielectric properties improvement.

In this study, we give a thorough evaluation of the structural, magnetic, and magnetocaloric properties in iron-rich PrFe11Ti intermetallic alloy with ThMn12-type structure using a combination of experimental and theoretical analysis. X-ray diffraction coupled with Rietveld refinement was used to characterize the structure, which revealed a unique tetragonal crystal structure with I4/mmm space group. The 8i site was identified as the preferred site for the Ti atom. This finding was confirmed by various techniques, including XRD, DFT, and Mössbauer spectrometry. Magnetic properties were studied through intrinsic magnetic measurements and magnetocaloric effect analysis. Mössbauer spectroscopy was employed to probe the local magnetic environment and for further characterization of the material’s magnetic properties. The experimental results were complemented by theoretical calculations based on density functional theory (DFT). A promising magnetocaloric effect is observed, with a significant maximum magnetic entropy (−ΔSMmax = 2.5 J·kg−1·K−1) and a relative cooling power about 70 J·kg−1 under low magnetic field change μ0ΔH = 1.5 T. Overall, our results provide a deeper understanding of the structural and magnetic properties of the material under study and demonstrate the effectiveness of the combined experimental and theoretical approach in the investigation of complex materials. The insights gained from this study could have implications for the development of advanced magnetic materials with enhanced properties for potential magnetic applications.

Herein, we report the influence of trivalent chromium (Cr3+) ion substitution on the electric, dielectric, and hyperfine interaction properties of a mixed Ni–Zn nanoferrite system synthesized by an auto combustion solution-gelation route. The XRD analysis verified the monophase nanocrystalline formation of prepared ferrites belonging to the spinel group with a cubic structure. TEM images displayed the sphere-like morphologies of the typical nanoferrite sample. FT-IR spectra uncover the occurrence of two absorption frequency bands in the desired region belonging to spinel ferrite. The magnetic parameters decreased significantly with increasing Cr3+ concentration. Mossbauer parameters, such as the hyperfine field, line-width, isomer shift and quadrupole splitting, were deduced for all the samples. DCR studies confirmed the semiconducting behavior of all the samples with an increasing resistivity trend after Cr3+ substitution. The dielectric study showed a decreasing trend with an increase in Cr3+ concentration. All the results display the influential substitution of Cr3+ ions in the Ni–Zn ferrite system, which shows the usability of the prepared samples in higher frequency ranging systems. [ABSTRACT FROM AUTHOR]

Thermally induced spin control is one of the main directions for future spin devices. In this study, we synthesized single-phase polycrystalline ErFe 1 − x CrxO3 and combined the magnetization curves and Mössbauer spectra to determine the macroscopic magnetism at room temperature (RT). The magnetization of the system at various temperatures is well simulated by molecular field theory. And it is found that under the Dzyaloshinskii–Moriya (DM) interaction, not only the B-site ions undergo a reorientation process, but the spins of the A-site ions also change at the same time. The effective spin is defined as the projection of Er 3 + on the Fe 3 + /Cr 3 + spin plane, and the whole reorientation process is obtained by fitting. This study will complement the actual process of ErFe 1 − x CrxO3 spin reorientation and will lay a theoretical foundation for the fabrication of future spin-controlled devices. Under the control of a certain temperature, the magnetic rare earth perovskite EFCO, in addition to the known spin reorientation of the B-site ions, also has a special spin turn of the A-site rare earth ions, that is, the value of the effective spin (the projection of the full spin on the B-site spin plane) also changes. [ABSTRACT FROM AUTHOR]

Magnetic Functional Nanomaterials Co1−yZnyRExFe2−xO4 (RE (rare-earth) = La,Sm,Gd) were prepared using the sol–gel combustion method. XRD characterization confirms that the ferrite samples we synthesized are single-phase cubic structures. The variation in the average crystalline size and lattice parameter is related to RE ion doping. The Mössbauer spectra of CoRExFe2−xO4 are two sets of magnetic six-wire peaks that indicate the ferrimagnetic behavior of the sample. The calcination temperature greatly influences the absorption area of Mössbauer for CoFe2O4, indicating that the calcination temperature affects the iron ion content at the octahedral B and tetrahedral A sites. Additionally, scanning electron microscopy measurements of the substituted specimens reveal that the ferrite powders are nanoparticles. With an increase in RE ions, the coercivity increases, and the saturation magnetization changes obviously. The XRD characterization of Co0.7Zn0.3LaxFe2−xO4 shows that the main crystalline phase of the sample is the cubic spinel structure phase, and there are fewer secondary crystalline phases. The lattice parameter tends to decrease with the substitution of La3+ ions. The average grain size decreased significantly with the increase in La content. From ferrimagnetic state transition to relaxation behavior, the hyperfine magnetic field decreases in La concentration by room temperature Mössbauer spectra. With the substitution of La3+ ions, both the saturation magnetization and coercivity of the samples were reduced, and the coercivity of all samples was lower.

The thermal decomposition of PbC2O4–FeC2O4.2H2O mixture (1:2 mol ratio) in air, prepared using impregnation method, aiming at the production of mixed oxides; PbO–Fe2O3 (1:1 mol ratio) system have been followed using differential thermal analysis-thermogravimetry (DTA-TG). The decomposition products as well as the phases’ transformations up to the ferrites production were characterized using X-ray diffraction (XRD), Fourier transform infrared (FT-IR) and Mössbauer spectroscopic techniques. DTA-TG showed the formation of mixed oxides at 400 °C through three well-defined steps due to dehydration and oxalates’ decomposition step. XRD, FT-IR and Mössbauer measurements at different calcination temperatures indicated the formation of paramagnetic fine grained Fe2O3 particles at early decomposition stages up to 250 °C followed by their transformation into magnetically ordered one by increasing calcination to 400 °C. The precursor calcined at 650 °C showed the initiation of PbFe4O7 ferrite formation besides the presence of unreacted PbO and Fe2O3 oxides. At 750 °C, only PbFe4O7 and PbFe2O5 ferrites can be detected. Kinetic analysis of TG steps using different computational methods, in the view of different solid–state reaction kinetic models, revealed the occurrence of the decomposition up to PbO–Fe2O3 through the random nucleation growth mechanism (A2). The activation parameters calculation indicated that the fine grained Fe2O3 particles formed at early stages increasing the interfaces between lead oxalate grains and thus facilitating the decomposition.

Novel iron(II) coordination compounds containing a ligand 2,6-bis(1H-imidazol-2-yl)pyridine (L), having such a composition as [FeL2]SO4·0.5H2O, [FeL2]Br2·H2O, [FeL2](ReO4)2, [FeL2]B10H10∙H2O, [FeL2]B12H12∙1.5H2O had been synthesized and studied using UV-Vis (diffuse reflectance), infrared, extended X-ray absorption fine structure (EXAFS), and Mössbauer spectroscopy methods, as well as X-ray diffraction and static magnetic susceptibility methods. The analysis of the μeff(T) dependence in the temperature range of 80–600 K have shown that all the obtained complexes exhibit a high-temperature spin crossover 1A1 ↔ 5T2. [ABSTRACT FROM AUTHOR]

In this work we produce Ba-hexaferrite nanoparticles by the ionic coordination reaction method and study the influence of La and Co ions on the magnetic properties of Ba 0.7 La 0.3 Fe 12-x Co x O 19 for x = (0.0, 0.25, 0.50, 0.75 and 1.0) nanoparticles. The crystalline and morphological properties were studied by X-ray diffraction and scanning electron microscopy techniques. The magnetic properties of samples were studied in a vibrating sample magnetometer under an applied field of ±6 T. The Fe occupancy in the three octahedral (12 k , 2 a , and 4 f 2), one tetrahedral (4 f 1) and one trigonal bipyramidal (2 b) sites was studied by Mössbauer spectroscopy. The samples are single domain nanoparticles with crystallite sizes in the range 71.5-50.1 nm, decreasing with the Co doping. The results suggest that the sample with x = 0.25 had the largest (BH) max of 6.98 kJ/m3, this effect is mostly due to the occupancy of 4 f 2 sites by Co2+. For x > 0.25, the Co2+ occupy mainly both the 4 f 2 and 12 k sites, the presence of oxygen vacancies is discussed. [ABSTRACT FROM AUTHOR]

Ubiquitous nanomaterials have been extensively involved in multifarious biotransformation of diverse organic and synthetic techniques. This research study describes the robust immobilization of α-amylase on magnetic nanoparticles of magnesium ferrite (MgFO) functionalized with silane. The XRD patterns, FESEM and HRTEM images were analysed to study structural and morphological features. The crystallite size of MgFO is found to be 12 nm. The FTIR results confirmed the covalent attachment of the enzyme with the MgFO and VSM and Mössbauer spectrometric graphs were evaluated to study the magnetic behaviour of the prepared samples. The Kinetic parameters, reusability, storage capacity and catalytic activity of the enzyme at various reaction time, pH and temperature conditions before and after attachment with MgFO were examined to confirm the successful immobilization process. The reusability of the enzyme on modified MgFO is found to be good (> 50%) even after 12 consecutive usability cycles and also retain 50% catalytic efficiency over 30 days storage period. [ABSTRACT FROM AUTHOR]

Short-range-ordered Fe(III) minerals such as ferrihydrite (Fh) are ubiquitous in the environment, are key players in biogeochemical cycling, and sorb trace elements and nutrients. As such, it is important to be able to identify the presence of such minerals in natural samples. Fh is commonly observed to be X‑ray amorphous and cannot be easily analyzed using X‑ray diffraction, meaning that spectroscopic methods such as X‑ray absorption or 57Fe Mössbauer spectroscopy (MBS) are necessary for accurate identification and quantification. Despite decades of research into Fh using MBS, there is a discrepancy in the literature about the exact parameters applicable to the mineral when measured at liquid helium temperature. Fh is frequently fitted with either one, two, or three hyperfine sextets with little interpretation applied to the meaning of each, which is problematic as a one sextet model does not account for the asymmetric lineshape frequently observed for Fh. Here, we address inconsistencies in the fitting of Fh and provide a more standardized approach to its identification by MBS. We present a systematic comparison of diferent fitting methods, notably based on Lorentzian and Voigt functions. We suggest that the most suitable approach to fitting pure Fh at liquid helium temperature is with two sextets (A and B) fitted using an extended Voigt-based function with the ability to apply probability distributions to each hyperfine parameter. 2-line Fh: A (δ = 0.49 mm/s; ε = 0.00 mm/s; Bhf = 50.1 T) and B (δ = 0.42 mm/s; ε = –0.01 mm/s; Bhf = 46.8 T) 6-line Fh: A (δ = 0.50 mm/s; ε = –0.03 mm/s; Bhf = 50.2 T) and B (δ = 0.40 mm/s; ε = –0.05 mm/s; Bhf = 47.1 T). We interpret the two sextets to be due to either diferences in the coordination environment of iron, i.e., in tetrahedral or octahedral sites, the presence of a disordered surface phase, or a combination of both. We hope that provoking a discussion on the use of MBS for Fh will help develop a greater understanding of this mineral, and other short-range ordered iron minerals, which are so important in environmental processes. [ABSTRACT FROM AUTHOR]

The effects of the addition of mango residue on the combustion of iron nitrate–urea mixtures are presented herein. The process was performed considering two systems: open (porcelain capsule) and closed (round-bottom flask), both with and without the addition of the residue, thus resulting in four different products. Thermogravimetric techniques (thermogravimetric analysis and differential thermal analysis) were used to assess the thermal behavior of the precursors, X-ray diffraction, Mossbauer spectroscopy and spectrometry in the infrared region with Fourier transform to analyze the influence of the synthesis parameters on the structure of the products, scanning electron microscopy, surface area, and porosity analysis, to analyze the morphology and textural properties of the samples. The addition of mango residue to either system caused changes in the combustion process, iron oxide phase, morphology, textural properties, and, particularly, the specific surface area in the closed system-produced material, in which a significant increase was observed. Thus, the addition of mango residue in the combustion synthesis of iron oxides can increase the added value of waste materials, thereby producing favorable economic and environmental impacts. [ABSTRACT FROM AUTHOR]

The syntheses, coordination chemistry, and Mössbauer spectroscopy of hepta-iron(III) complexes using derivatised salicylaldoxime ligands from two categories; namely, 'single-headed' (H 2 L ) and 'double-headed' (H 4 L ) salicylaldoximes are described. All compounds presented here share a [Fe 3 -µ 3 -O] core in which the iron(III) ions are µ 3 -hydroxo-bridged in the complex C1 and µ 3 -oxo-bridged in C2 and C3 . Each compound consists of 2 × [Fe 3 -µ 3 -O] triads that are linked via a central [Fe(µ 2 -OH) 6 ] 3- ion. In addition to the charge balance and microanalytical evidence, Mössbauer measurements support the fact that the triads in C1 are µ 3 -OH bridged and are µ 3 -O bridged in C2 and C3 .

AyB1−yCxFe2−xO4 (C=Ho,Gd,Al) ferrite powders have been synthesized by the sol-gel combustion route. The X-ray diffraction of the CoHoxFe2−xO4 (x = 0~0.08) results indicated the compositions of single-phase cubic ferrites. The saturation magnetisation of CoHoxFe2−xO4 decreased by the Ho3+ ions, and the coercivity increased initially and then decreased with the increase of the calcination temperature. The Mössbauer spectra indicated that CoHoxFe2−xO4 displays a ferrimagnetic behaviour with two normal split Zeeman sextets. The magnetic hyperfine field tends to decrease by Ho3+ substitution owing to the decrease of the A–B super-exchange by the paramagnetic rare earth Ho3+ ions. The value of the quadrupole shift was very small in the CoHoxFe2−xO4 specimens, indicating that the symmetry of the electric field around the nucleus is good in the cobalt ferrites. The absorption area of the Mössbauer spectra changed with increasing Ho3+ substitution, indicating that the substitution influences the fraction of iron ions at tetrahedral A and octahedral B sites. The X-ray diffraction of Mg0.5Zn0.5CxFe2−xO4(C=Gd,Al) results confirmed the compositions of single-phase cubic ferrites. The variation of the average crystalline size and lattice constant are related to the doping of gadolinium ions and aluminum ions. With increasing gadolinium ions and aluminum ions, the coercivity increased and the saturation magnetization underwent a significant change. The saturation magnetization of AlMg0.5Zn0.5FeO4 ferrite reached a minimum value (MS= 1.94 mu/g). The sample exhibited ferrimagnetic and paramagnetic character with the replacement with Gd3+ ions, that sample exhibited paramagnetic character with the replacement with Al3+ ions, and the isomer shift values indicated that iron is in the form of Fe3+ ions.

Pulsed laser ablation in liquids was utilized to prepare NiFe2O4 (NFO) and CoFe2O4 (CFO) nanoparticles from ceramic targets. The morphology, crystallinity, composition, and particle size distribution of the colloids were investigated. We were able to identify decomposition products formed during the laser ablation process in water. Attempts to fractionate the nanoparticles using the high-gradient magnetic separation method were performed. The nanoparticles with crystallite sizes in the range of 5–100 nm possess superparamagnetic behavior and approximately 20 Am2/kg magnetization at room temperature. Their ability to absorb light in the visible range makes them potential candidates for catalysis applications in chemical reactions and in biomedicine. [ABSTRACT FROM AUTHOR]

Egyptian granite was used in preparing some glass samples including different contents of sodium carbonate as a fluksing agent and to study the effect of different Na+ ions on some of their properties. The prepared glass samples have the chemical composition [100 -x granite.xNa2CO3, Where x = 11, 12, 13, 14 and 15 mol%]. The mixture of each sample was mixed well and prepared in a platinum crucible at 1430 °C for one hour, then quenched in air between two copper plates. The as prepared glass samples were investigated by XRD, FTIR, Mössbauer spectrometer, d.c. and a.c. conductivities. XRD results showed that the prepared samples have the glassy nature. FTIR results showed approximately similar de-convoluted bands. The identification of these bands revealed that the present vibration modes in these samples were Si-O-Si bending vibration, Si-O-Al stretching and Si-O-Si symmetric, Si-O− and Si-O-Si asymmetric stretching. Mössbauer results revealed that the granite spectrum showed two magnetic sites [Fe3O4 (Fe III) A site and Fe3O4 (Fe II, III) B site]. And also another two doublets represented Fe (II) and Fe (III). The glass samples spectra showed two doublets represented Fe2+ and Fe3+ (Oh). The a.c. conductivity at low temperature for the glass samples showed week temperature dependence and strong frequency dependence. At high temperature the behavior reversed. The a.c. behavior showed also that the relation of ln(σ) and 1/T of each glass sample exhibited one line with two slopes. This reflects that the electric conduction is due to ionic and electronic conduction. The behavior of the relation between Na+ content and ln(σ) showed the behavior of the extrinsic semiconductor at low temperature range where the pentavalent or trivalent ions of silicon matrix changed their electrical features producing p-type and n-type semiconductors respectively. The dielectric constant (ε') showed fixed values up to a certain temperature, then ε' started to increase gradually with inversely proportional to frequency. [ABSTRACT FROM AUTHOR]

Solid-state physics research has long employed radioactive isotopes to investigate the crystallographic, electric and magnetic properties of nanostructures. Ion implantation (1–100 keV) is the method of choice for incorporating radioactive nuclei into the crystal structure. However, the enormous scientific interest in 2D materials, multiferroics and their interfaces of the last decades has lead to more stringent demands for isotope incorporation. Ultra-low energy (ULE) ion implantation (10–100 eV) provides the ability to precisely tune the depth of the implanted radioactive probes, even in the case of atomically thin 2D materials. To unlock this potential and expand the experimental capabilities of the ISOLDE collaboration in CERN, the apparatus for surface physics and interfaces at CERN (ASPIC), an experienced ultra-high vacuum chamber dedicated to surface characterization and modification, is refurbished and upgraded with a new component: the ASPIC's ion implantation (ASCII) chamber, designed for ULE ion implantation of radioactive probes. This paper describes the scientific context, design and application of these vacuum chambers. [ABSTRACT FROM AUTHOR]

Magnetite nanoparticles were deposited on Douglas fir biochar (Fe 3 O 4 /DFBC) using aqueous, NaOH-induced chemical co-precipitation from Fe2+/Fe3+ salt solutions. Fe 3 O 4 /DFBC was used to remediate As(V)-contaminated water. Kinetics and isotherms were studied. pH 5 was selected as the optimized pH due to low iron leaching and closeness to groundwater pH. Adsorption equilibrium was reached after 3 h, 2 h, and 1 h for 0.5, 5, and 50 mg/L initial As(V) concentrations, respectively. Adsorption was endothermic, and the Langmuir capacity was 6.33 mg/g at 25 °C. Ionic strength, impacts of Fe 3 O 4 /DFBC particle size, and competitive ion/molecule effects during As(V) adsorption were studied. Continuous-flow fixed-bed column breakthrough studies performed at 0.5, 5, and 50 mg/L of As(V) at pH 5 exhibited maximum capacities of 3.47, 3.99, and 3.72 mg/g, respectively. Aqueous potassium phosphate was used successfully for column regeneration. Fe 3 O 4 /DFBC was characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), and Mössbauer spectroscopy before and after As(III) and As(V) adsorption. Mössbauer found the "Fe 3 O 4 " was composed of several phases. A key target was the study of simultaneous toxic As(III) adsorption and its transformation to As(V) from pH 1–13. The highest removal of As(III) and oxidized As(V) was obtained at pH 3. The relationship between iron leaching and pH was investigated and the pH-dependent surface adsorption was monitored using X-ray photoelectron spectroscopy (XPS) from pH 1 to 13. One goal of this study was to enhance the understanding of the adsorption characteristics needed for initial scaling of a treatment facility that can efficiently remediate arsenic-contaminated wastewater. Experiments were conducted using batch and fixed bed continuous flow columns to optimize adsorption process parameters under various circumstances and solution matrices. Another goal was to further establish the surface structures of the chemisorbed arsenates versus pH. [Display omitted] • As(III) can be oxidized to As(V) in anoxic conditions when adsorbed. • Solution effects, dose optimizations, column separations, and Fe2+/3+ leaching versus pH were studied during As(V) removal. • AsO 4 3− adsorption capacity was 6.33 mg/g at 25 °C. • Redox transformation of As(III) to As(V) on Fe 3 O 4 /DFBC was studied from pH 1 to 13. • Mössbauer spectroscopy and pH-dependent XPS aided detailed mechanistic understanding. [ABSTRACT FROM AUTHOR]

[Display omitted] • Double metal oxalates, MM'(C 2 O 4) 2 ⋅4H 2 O. • Triple metal oxalates, MM'M"(C 2 O 4) 3 ⋅6H 2 O. • Structural characteristics. • 57Fe-Mössbauer spectroscopy. • Discussion of hyperfine parameters. 57Fe-Mössbauer spectra of double MM'(C 2 O 4) 2 ⋅4H 2 O (M = Fe, M' = Mg, Co, Zn) and triple metal oxalates MM'M"(C 2 O 4) 3 ⋅6H 2 O (M = Fe, M' = Mg, Mn, Co; M" = Zn) were recorded at room temperature and briefly discussed on the basis of their structural characteristics. No changes in the hyperfine interactions at the 57Fe site were detected because of the presence of the other metal ions. [ABSTRACT FROM AUTHOR]

Nickel ferrite nanoparticles doped with zinc were synthesized at a lower reaction temperature of 180 ° C. The research delved into their structural, optical, dielectric, and magnetic properties. These nanoparticles exhibited a distinct cubic spinel structure, with crystallite sizes ranging from 33 to 51 nm. FTIR analysis revealed metal oxide stretching vibrations between 400–600 nm. FESEM and HR-TEM examinations unveiled irregularly shaped nano-particles. XPS analysis disclosed the chemical states of Zn 2 + , Fe 3 + , and Ni 2 + ions. Mossbauer spectra exhibited two sextet patterns related to tetrahedral (A) and octahedral (B) sites, plus a weak doublet pattern. Magnetic tests showed a decrease in saturation magnetization (Ms) but an increase in remanent magnetization (Mr) and coercivity (Hc) values upon doping. [ABSTRACT FROM AUTHOR]

Carbonatite is an igneous rock that is composed mainly of carbonate minerals and silicates. It is recently applied as fertilizer due to its high content of calcite and dolomite. This study presents a physical and chemical characterization of the Spanish River Carbonatite (SRC) and its application as fertilizer is tested. The chemical composition obtained by X-ray fluorescence and Energy Dispersive X-ray analyses indicates that Ca, Fe and Si are the main contained elements. Calcite and SiO2 are the principal mineralogical phases as detected by X-ray diffraction. Fourier transform infrared spectroscopy confirms the presence of calcite, silicates and also organic material and water. It also suggests the presence of vermiculite. Thermal analysis reveals only a one-step reaction that corresponds to the decomposition of calcite. Mössbauer spectroscopy performed at room temperature do not show magnetic order between the iron moments instead it shows Fe2+ and Fe3+ doublets in M1 and M2 octahedral sites belonging to vermiculite. At 50 K, we observe that the isomer shift increases their values due to the second order Doppler shift. SQUID magnetometry measurements reveal that most of the sample contains paramagnetic domains assigned to the silicates and calcite components. However, under low applied fields, a tiny signal for Verwey transition appears at 124 K (suggesting the presence of magnetite) although screened by the strong paramagnetic signal of the main components. The SRC has been tested as potential fertilizer on sweet cucumber (Solanum muricatum) which responded positively to the application to carbonatite as an amendment, expressing itself in high foliar biomass. [ABSTRACT FROM AUTHOR]

The complementary investigation techniques, Mossbauer spectroscopy, transmission electron microscopy with selected area electron diffraction (TEM/SAED), X-ray diffraction (XRD) have been used to investigate the fate of the Valea lui Stan, Romania, gold-ore nanoscale-minerals during the long time of residence in the waste dumps. The preliminary investigations showed such waste dumpsto contain significant amount of metals which cannot be identified by conventional methods. An intense research activity started up in order to evaluate the possibilities to recycle Valea lui Stan waste dumps and to recover metals by chemical or phytoextraction procedures. The waste dumps naturally show different mineral constituents with clay minerals as major phases, observed by XRD-technique. Although thewaste dumpsmaterials havewhitish-yellowish colours, MOSSBAUER technique evidences the presence of the finely dispersed iron bearing minerals. The authors are focusing to inspect and analyze Fe-compoundsin the samples collected from Valea lui Stan's waste dumps in order to identify the magnetic phases by Mossbauer technique. [ABSTRACT FROM AUTHOR]

Nanocrystalline NixZn1-xFe2O4 ferrite was prepared using the microwave-assisted sol-gel auto combustion method. The nanocrystalline ferrite was characterized by powder XRD, SEM, FT-IR, VSM, Mossbauer, magnetic and dielectric study. The lattice constant, tetrahedral radius, octahedral radius, anion parameter, average crystalline size, tetrahedral bond length, octahedral bond length, and deviation parameter have been estimated from XRD and compared with standard results. The magnetic properties of the prepared ferrite were studied and parameters like saturation magnetization, magnetic remnant, magnetic moment, coercivity, and SQR were estimated. The effect of substitution on isomer shift and magnetic exchange interaction between octahedral and tetrahedral sites on magnetic properties were discussed from Mossbauer’s study. It was observed that the isomer shift does not vary appreciably with a concentration of nickel in zinc lattice. Moreover, the exchange interaction between Fe3+ ions at tetrahedral and octahedral sites and the doped nickel ions prefer the octahedral sites that strongly favor the magnetic interactions. The temperature dependence AC susceptibility was measured to know the magnetic phase transition. The dielectric constant and tangent loss are high at lower frequencies, decreasing with frequency and finally becoming almost constant. The dielectric constant ε′ was also found to increase with the increase in Ni2+ content.