Mössbauer Spectroscopy Research Papers - Academia.edu (original) (raw)

Sr1.50Ca1.50Fe2.25Mo0.75O9– and Sr1.92Ca1.08Fe2.04W0.96O9– double perovskites are synthesized in the polycrystalline form by a solid-state reaction route in air and studied at room temperature using the of PXRD, Raman and Mössbauer... more

Sr1.50Ca1.50Fe2.25Mo0.75O9– and Sr1.92Ca1.08Fe2.04W0.96O9– double perovskites are synthesized in
the polycrystalline form by a solid-state reaction route in air and studied at room temperature
using the of PXRD, Raman and Mössbauer spectroscopy techniques. The Rietveld refinement
analysis reveals that both compounds adopt a tetragonal system with the space group I4/m and
lattice parameters a = b = 5.5176(1) Å and c = 7.8065(2) Å for Sr1.50Ca1.50Fe2.25Mo0.75O9– and
a = b = 5.5453(1) Å and c = 7.8388(1) Å for Sr1.92Ca1.08Fe2.04W0.96O9–. Raman spectra are consistent
with the group theoretical analysis predicted for tetragonal symmetry I4/m (point group
5
C4h ). 57Fe Mössbauer spectra recorded at room temperature show a paramagnetic behavior for
Sr1.50Ca1.50Fe2.25Mo0.75O9–, and magnetic ordering for Sr1.92Ca1.08Fe2.04W0.96O9–. The isomer
shift () and quadrupole splitting () values are characteristic of high-spin Fe3+ in a distorted
octahedral coordination.

Zinc plant residue (ZPR) is a secondary material generated during hydrometallurgical zinc production that contains considerable contents of valuable elements such as Zn, Cu, Fe, Pb, Cd, Ag, In, Ga, Tl. Zinc, copper and accompanying... more

Zinc plant residue (ZPR) is a secondary material generated during hydrometallurgical zinc production that contains considerable contents of valuable elements such as Zn, Cu, Fe, Pb, Cd, Ag, In, Ga, Tl. Zinc, copper and accompanying elements in ZPR are in different minerals, mainly in the ferrites. A promising approach for recycling ZPR is the sulfating roasting using iron sulfates followed by water leaching. In this study, the composition of ZPR and the obtained products were thoroughly investigated by various methods including X-ray diffraction analysis (XRD), chemical phase analysis and Mössbauer spectroscopy. The effect of temperature, amount of iron sulfates and roasting time on the conversion of valuable metals into a water-soluble form was thermodynamically and experimentally studied both using pure ferrites and ZPR. Based on the results of time-resolved XRD analysis and synchronous thermal analysis (STA), a mechanism of the sulfation roasting was elucidated. The rate-controll...

To investigate the potential of tourmaline as a geochemical monitor, a comprehensive dataset on major, minor and trace element concentrations as well as Fe 3+ /Fe ratios of tourmaline is presented. The dataset includes samples from five... more

To investigate the potential of tourmaline as a geochemical monitor, a comprehensive dataset on major, minor and trace element concentrations as well as Fe 3+ /Fe ratios of tourmaline is presented. The dataset includes samples from five plutonic complexes related to diverse magmatic to hydrothermal stages of the Cornubian Batholith (SW England). Tourmaline composition found in barren and cassiterite-bearing samples include all three primary tourmaline groups and tourmaline species with the general endmembers schorl, dravite, elbaite, uvite, feruvite, foitite and Mg-foitite. Based on textures and compositions, it is possible to distinguish not only between late-magmatic and hydrothermal tourmaline, but also between several formation stages. Hence, tourmaline monitors late-magmatic processes and the partitioning of elements during exsolution of an aqueous phase. For example , in hydrothermal tourmaline Sn is strongly enriched, while Ti, Cr, V and Sc are depleted compared to late-magmatic tourmaline of the same sample. Several tourmaline generations that precipitated from magmatic fluids can be distinguished with differing major and minor elements and REE patterns depending on the composition of the melt from which they were expelled from. Strongly zoned tourmaline allows for unraveling the hydrothermal history of a distinct location including ore precipitation. The precipitation of SnO 2 in the study area was probably caused by mixing between acidic, reduced, Sn-bearing magmatic fluids and oxidized meteoric fluids, which is in agreement with London and Manning (1995) and Williamson et al. (2000). Hence, the ability of tourmaline composition to monitor changes in Sn concentration and redox conditions in hydrothermal fluids has potential as an exploration tool.

A series of Ni x Zn 1 À x Fe 2 O 4 (x ¼ 0.5, 0.6 and 0.7) ferrite nanoparticles have been synthesized using a co-precipitation technique, in order to understand the doping effect of nickel on their structural and magnetic properties. XRD... more

A series of Ni x Zn 1 À x Fe 2 O 4 (x ¼ 0.5, 0.6 and 0.7) ferrite nanoparticles have been synthesized using a co-precipitation technique, in order to understand the doping effect of nickel on their structural and magnetic properties. XRD and FTIR studies reveal the formation of spinel phase of ferrite samples. Substitution of nickel has promoted the growth of crystallite size (D), resulting the decrease of lattice strain (η). It was also observed that the lattice parameter (a) increases with the increase of Ni 2 þ ion concentration. All particles exhibit superparamagnetism at room temperature. The hyperfine interaction increases with the increase of nickel substitution, which can be assumed to the decrease of core–shell interactions present in the nanoparticles. The Mössbauer studies witness the existence of Fe 3 þ ions and absence of Fe 2 þ ions in the present systems. These superparamagnetic nanoparticles are supposed to be potential candidates for biomedical applications. The results are interpreted in terms of microstructure, cation redistribution and possible core–shell interactions.

An attempt has been made to prepare nanocrystalline nickel substituted lithium ferrites, having chemical composition Li 0.5 À 0.5x Ni x Fe 2.5 À 0.5x O 4 (where x ¼0.0–1.0 with a step increment of 0.2) by a citrate-gel auto combustion... more

An attempt has been made to prepare nanocrystalline nickel substituted lithium ferrites, having chemical composition Li 0.5 À 0.5x Ni x Fe 2.5 À 0.5x O 4 (where x ¼0.0–1.0 with a step increment of 0.2) by a citrate-gel auto combustion method. Structural characterization of the synthesized samples was carried out by X-ray diffraction analysis (XRD) and field emission scanning electron microscopy (FESEM). Magnetic measurements were carried out using vibrating sample magnetometer (VSM) and Mossbauer spectroscopy. From these measurements it is observed that Ni 2 þ substitution in lithium ferrites has strong influence on magnetic properties. Hysteresis loops indicate that the saturation magnetization values were decreased from 56 emu/gm to 28 emu/gm by increasing the Ni 2 þ content in the Li–Ni ferrite samples. This signifies the fact that the lesser magnetic Ni 2 þ ions are substituted for the magnetic Fe 3 þ ions in the octahedral sub-lattice of the ferrites. Field Cooled (FC) and Zero Field Cooled (ZFC) magnetization measurements under an applied field of 100 Oe and 1000 Oe in the temperature range of 5–375 K were performed on two samples Li 0.1 Ni 0.8 Fe 2.1 O 4 and NiFe 2 O 4. The magnetization as a function of an applied field 10 T was carried out at two different temperatures 5 K and 310 K. These measurements showed the blocking temperature of the two samples at around 350 K above which the materials show super-paramagnetic behavior where the coercivity and remanence magnetization are almost zero.

Occupation of Fe in ZnO structure X-ray diffraction Mössbauer spectroscopy UV-Vis diffuse reflectance spectroscopy A B S T R A C T A series of Fe-doped ZnO (Zn 1-x Fe x O, x = 0, 0.01, 0.03, 0.05, 0.07 and 0.10) samples were synthesized... more

Occupation of Fe in ZnO structure X-ray diffraction Mössbauer spectroscopy UV-Vis diffuse reflectance spectroscopy A B S T R A C T A series of Fe-doped ZnO (Zn 1-x Fe x O, x = 0, 0.01, 0.03, 0.05, 0.07 and 0.10) samples were synthesized by solution combustion synthesis method using metal nitrates as oxidizers and glycine as fuel. A spongy network-type microstructure is observed by the SEM micrographs of all the synthesized samples. For Fe concentration lower than 0.05 (x ≤ 0.05), formation of phase-pure wurtzite (hexagonal) structured Zn 1-x Fe x O powder with P6 3 mc space group was confirmed from the X-ray diffraction results. However, for x ≥ 0.07, precipitation of ZnFe 2 O 4 impurity phase was observed. Hence, the solubility limit for Fe in ZnO lattice is about x = 0.05 for the samples synthesized by solution combustion method. Two quadruple doublets observed in the 57 Fe-Mössbauer spectra for each of the samples suggest that paramagnetic Fe 3+ cations occupy two different lattice sites in the ZnO structure; they are the substitutional sites (1) without distortion of the surrounding structure and (2) with distortion due to the defects present in the surrounding structure. In the DRS spectra, an Urbach-like tail was observed in the band gap region, indicating that Fe-doping in the ZnO lattice modifies the electronic structure and enhances the absorption of visible light. Furthermore, the Kubelka-Munk plots suggest the presence of two different local structures validating the Mössbauer results. We studied the photocatalytic degradation of me-thylene blue dye using these Fe doped ZnO samples as catalysts and the studies revealed that presence of Fe could lead to the formation of carbonaceous material on the surface of the solution combustion synthesized Zn 1-x Fe x O samples. Overall, our results demonstrate the structural characteristics of Fe in Fe-doped ZnO samples synthesized by solution combustion method.

Single phase MFeCrO 4 (M = Co/Ni) nanosized samples are prepared by solution combustion method using glycine as fuel. Lattice parameter obtained after Rietveld refinement of the powder x-ray diffraction pattern of CoCrFeO 4 and NiCrFeO 4... more

Single phase MFeCrO 4 (M = Co/Ni) nanosized samples are prepared by solution combustion method using glycine as fuel. Lattice parameter obtained after Rietveld refinement of the powder x-ray diffraction pattern of CoCrFeO 4 and NiCrFeO 4 samples are 8.374 and 8.325 Å and corresponding crystallite sizes are 40 and 27 nm, respectively. FTIR spectra of both samples show tetrahedral and octahedral metal oxygen bond stretching peaks at 596 and 488 cm −1 , indicating spinel phase formation. DC magnetisation study indicates that both samples are ferrimagnetic at room temperature, with CoCrFeO 4 having a higher value of saturation magnetisation. Mössbauer spectra indicate the presence of magnetic relaxation in the samples. Also, the strength of interaction with nearest neighbour Fe 3+ cations is higher in NiCrFeO 4 .

We argue in favor of the physical basis of YARK theory of gravity and show that the major part of recent criticism by Corda (Corda, C. Symmetry 2018, 10, 558-559) is based on either irrelevant or erroneous claims. We highlight a perfect... more

We argue in favor of the physical basis of YARK theory of gravity and show that the major part of recent criticism by Corda (Corda, C. Symmetry 2018, 10, 558-559) is based on either irrelevant or erroneous claims. We highlight a perfect agreement of YARK theory with the results of the Mössbauer experiments in a rotating system and demonstrate that the so-called "synchronization effect" proposed by Corda to account for the outcome of these experiments stems from an elementary mathematical error and must be rejected. Finally, we show that YARK theory provides a consistent alternative explanation of the origin of the LIGO signals beyond the hypothesis about gravitational waves. [http://vixra.org/pdf/1902.0070v1.pdf]

Phase transformation in cement during hydration is studied by XRD, FTIR and Mössbauer. The hydration process was monitored by self consistent analysis of the XRD results. Alite and belite phases control the early setting time of cement.... more

Phase transformation in cement during hydration is studied by XRD, FTIR and Mössbauer. The hydration process was monitored by self consistent analysis of the XRD results. Alite and belite phases control the early setting time of cement. Mössbauer spectroscopy results suggest that brownmillerite prolongs setting time. a b s t r a c t We report the phase transformations in Portland cement before and after hydration. The hydration mechanism was studied in detail by using a full Rietveld refinement of the X-ray diffraction (XRD) patterns, Fourier Transformed Infra-Red (FTIR) spectroscopy, Thermogravimetric Analysis (TGA) and Mössbauer spectroscopy at room temperature. From the Rietveld refinement of XRD data, alite, belite, celite, brown-millerite and low quartz phases were detected and quantified as major phases in dry cement powder. After hydration, calcium carbonate, portlandite and ettringite phases were found to form. A large reduction in the amounts of alite and belite phases were observed suggesting the formation of amorphous C–S–H phase and emphasizing the role of alite phase in flash setting of cement, as justified by the XRD and FTIR spectroscopy. Mössbauer spectra of all the unset samples showed quadrupole split doublets corresponding to the brownmillerite phase which remains unchanged even after about one week of hydration, suggesting that brownmillerite did not transform to other phases during initial stage of hydration process.

The structural and magnetic properties of lithium ferrite nanoparticles synthesized through the solution combustion route at different fuel to oxidizer ratio are studied using different techniques. Powder X-ray diffraction studies show... more

The structural and magnetic properties of lithium ferrite nanoparticles synthesized through the solution combustion route at different fuel to oxidizer ratio are studied using different techniques. Powder X-ray diffraction studies show that the fuel to oxidizer ratio is a critical parameter that determines the phase purity and degree of order of the samples. Magnetic studies show that the saturation magnetization and coercivity are comparable to those reported for lithium ferrites prepared using other methods. Saturation magnetization of Li0.8 sample at room temperature is 60 emu/g and is close to the bulk value. The hyper-fine parameters obtained from the Mössbauer spectra of Li0.6 and Li0.8 also match the reported values of phase pure samples. Mössbauer spectra of samples prepared at stoichiometric and fuel rich conditions show the presence of Fe 2+ cations in the ferrite phase, indicating that a reducing environment which reduces Fe 3+ to Fe 2+ ions is created as the fuel to oxidizer ratio is increased. The variation in the structural and magnetic properties of the samples, combined with TGA and FTIR studies, shows that the fuel lean condition is more appropriate for the direct formation of single phase lithium ferrite nanoparticles.

This chapter provides an overview of results obtained by a variety of spectroscopic techniques. The most common techniques employed are infrared and Raman spectroscopy, which enable detailed observation of in particular the behaviour of... more

This chapter provides an overview of results obtained by a variety of spectroscopic techniques. The most common techniques employed are infrared and Raman spectroscopy, which enable detailed observation of in particular the behaviour of water and OH-groups and the type of H-bonds formed. The inner-surface OH-groups that normally form H-bonds with adjacent layers in the kaolins, form H-bonds with water in the interlayer in halloysite. IES showed that the four inner and inner-surface OH-groups were removed at different temperatures and/or at different rates. A slight increase in the Al 2p binding energy observed in the XPS spectra from kaolinite to halloysite reflects a change in the stacking order due to the interlayer water. The overall shape of the O 1s is indicative of two peaks associated with the oxygen atoms and with the OH-groups. A third, very weak peak was observed associated with interlayer water still present despite the ultrahigh vacuum.

Mg substituted X–type hexagonal ferrites with the chemical composition Ba2Zn2-xMgxFe28O46 (x = 0.0, 0.4, 0.8, 1.2, 1.6 and 2.0) were successfully synthesised by a sol–gel auto–combustion technique, in order to investigate the effect of... more

Mg substituted X–type hexagonal ferrites with the chemical composition Ba2Zn2-xMgxFe28O46 (x = 0.0, 0.4, 0.8, 1.2, 1.6 and 2.0) were successfully synthesised by a sol–gel auto–combustion technique, in order to investigate the effect of Mg substitution on structural, magnetic and dielectric properties. XRD analysis of prepared samples revealed the formation of pure X–type phase. The variations (decreasing trend) in lattice parameters with Mg substitution indicate the incorporation of Mg substitution into the crystal structure. The average crystallite size of heated powders was found to be in the range of 16–22 nm. For the first time, the RT hysteresis loops of Ba2Zn2Fe28O46 (Zn2X), Ba2Mg2Fe28O46 (Mg2X) and Ba2Zn2-xMgxFe28O46 (x = 0.0, 0.4, 0.8, 1.2, 1.6 and 2.0) were measured. The saturation magnetisation showed an initial decrease with x = 0.4 1.2, and then an increase with x > 1.2, to the largest final values of 63.29 A m2 kg−1 for the fully Mg–substituted x = 2.0. The value of coercivity lies in the range of 89.9–209.3 kA m−1 (1130–2630 Oe), and the magnetic results suggest that the compositions x = 0.0, 0.4 and 1.2 possess multi-domain microstructures, while x = 0.8, 1.6 and 2.0 possess single domain microstructures. The room temperature Mӧssbauer spectra were analysed with six sextets of five magnetic sublattices, and the results are presented as a function of Mg substitution. It was found that initial levels of Mg substitution reduce the Fe populations at a and b (spin up) sublattices, but that with x > 1.2 these become repopulated at fIV (spin down) site, resulting in an increase in magnetisation. Dielectric parameters such as dielectric constant and loss factor were studied as a function of frequency, and results show normal behaviour for ferrimagnetic materials. At low frequencies (100 Hz–2 MHz), relative permittivity was constant between 0.3 and 1.5 above 20 kHz, with the higher values belonging to the more dense samples. All Mg substituted samples had lower losses above 20 kHz than the pure Zn2X. In complex measurements at microwave frequencies (500 MHz–13.5 GHz), all samples had a real permittivity of around 7.5, except for the fully Mg–substituted sample (x = 2.0), which had a lower ε′ of 5.5. For two samples (x = 0.4 and 1.6) we observed dielectric resonances between 12.85 and 13.25 GHz. All showed a steady real permeability of around 1.2–1.5 over the whole 1–13 GHz range, and ferromagnetic resonance (FMR) between 1 and 5 GHz, and ∼12.5 GHz.

Recently, Klaus Kassner posted an elaborate analysis on ResearchGate [1] where he criticizes the novel gravitation theory developed by T. Yarman and his colleagues-and in particular, M. Arik and A. Kholmetskii (whose initials altogether... more

Recently, Klaus Kassner posted an elaborate analysis on ResearchGate [1] where he criticizes the novel gravitation theory developed by T. Yarman and his colleagues-and in particular, M. Arik and A. Kholmetskii (whose initials altogether make up the designation "YARK theory" for easy reference). To this effect, Dr. Kassner claimed to have pinned down errors in a series of our publications with respect to Mössbauer experiments in a rotating system. Owing to the fact that a major portion of his critique already happens to be answered in several of our contributions put in print in the last few years, we shall keep our response as brief as possible.

Ferrofluids are nanomaterials consisting of magnetic nanoparticles that are dispersed in a carrier fluid. Their physical properties, and hence their field of application are determined by intertwined compositional, structural, and... more

Ferrofluids are nanomaterials consisting of magnetic nanoparticles that are dispersed in a carrier fluid. Their physical properties, and hence their field of application are determined by intertwined compositional, structural, and magnetic characteristics, including interparticle magnetic interactions. Magnetic nanoparticles were prepared by thermal decomposition of iron(III) chloride hexahydrate (FeCl 3 ·6H 2 O) in 2-pyrrolidone, and were then dispersed in two different fluids, water and polyethylene glycol 400 (PEG). A number of experimental techniques (especially, transmission electron microscopy, Mössbauer spectroscopy and superconducting quantum interference device (SQUID) magnetometry) were employed to study both the as-prepared nanoparticles and the ferrofluids. We show that, with the adopted synthesis parameters of temperature and FeCl 3 relative concentration, nanoparticles are obtained that mainly consist of maghemite and present a high degree of structural disorder and strong spin canting, resulting in a low saturation magnetization (~45 emu/g). A remarkable feature is that the nanoparticles, ultimately due to the presence of 2-pyrrolidone at their surface, are arranged in nanoflower-shape structures, which are substantially stable in water and tend to disaggregate in PEG. The different arrangement of the nanoparticles in the two fluids implies a different strength of dipolar magnetic interactions, as revealed by the analysis of their magnetothermal behavior. The comparison between the magnetic heating capacities of the two ferrofluids demonstrates the possibility of tailoring the performances of the produced nanoparticles by exploiting the interplay with the carrier fluid.

Ferrimagnetic oxides may contain single or multi domain particles which get converted into super-paramagnetic state near a critical size. To explore the existence of these particles, we have made Mössbauer and magnetic studies of Cu 2 þ... more

Ferrimagnetic oxides may contain single or multi domain particles which get converted into super-paramagnetic state near a critical size. To explore the existence of these particles, we have made Mössbauer and magnetic studies of Cu 2 þ substitution effect in CoFe 2 À x O 4 Ferrites (0.0, 0.1, 0.2, 0.3, 0.4, and 0.5). All the samples have a cubic spinel structure with lattice parameters increasing linearly with increase in Cu content. The hysteresis loops yield a saturation magnetization, coercive field, and re-manent magnetization that vary significantly with Cu content. The magnetic hysteresis curves shows a reduction in saturation magnetization and an increase in coercitivity with Cu 2 þ ion substitution. The anisotropy constant, K 1, is found strongly dependent on the composition of Cu 2 þ ions. The variation of saturation magnetization with increasing Cu 2 þ ion content has been explained in the light of Neel's molecular field theory. Mössbauer spectra at room temperature shows two ferrimagnetically relaxed Zeeman sextets. The dependence of Mössbauer parameters such as isomer shift, quadrupole splitting, line width and hyperfine magnetic field on Cu 2 þ ion concentration have been discussed.

In the present paper, the adsorption of amino acids (Ala, Met, Gln, Cys, Asp, Lys, His) on clays (bentonite, kaolinite) was studied at different pH (3.00, 6.00, 8.00). The amino acids were dissolved in seawater, which contains the major... more

In the present paper, the adsorption of amino acids (Ala, Met, Gln, Cys, Asp, Lys, His) on clays (bentonite, kaolinite) was studied at different pH (3.00, 6.00, 8.00). The amino acids were dissolved in seawater, which contains the major elements. There were two main findings in this study. First, amino acids with a charged R group (Asp, Lys, His) and Cys were adsorbed on clays more than Ala, Met and Gln (uncharged R groups). However, 74% of the amino acids in the proteins of modern organisms have uncharged R groups. These results raise some questions about the role of minerals in providing a prebiotic concentration mechanism for amino acids. Several mechanisms are also discussed that could produce peptide with a greater proportion of amino acids with uncharged R groups. Second, Cys could play an important role in prebiotic chemistry besides participating in the structure of peptides/proteins. The FT-IR spectra showed that the adsorption of amino acids on the clays occurs through the amine group. However, the Cys/clay interaction occurs through the sulfhydryl and amine groups. X-ray diffractometry showed that pH affects the bentonite interlayer, and at pH 3.00 the expansion of Cys/bentonite was greater than that of the samples of ethylene glycol/bentonite saturated with Mg. The Mössbauer spectrum for the sample with absorbed Cys showed a large increase (˜20%) in ferrous ions. This means that Cys was able to partially reduce iron present in bentonite. This result is similar to that which occurs with aconitase where the ferric ions are reduced to Fe 2.5.

Keywords: Evolved and slightly evolved glauconite Condensed section Rim and core of glauconite pellet Mössbauer spectroscopy of glauconite Reverse glauconitization Vermiforms A detailed mineral chemical investigation of glauconite within... more

Keywords: Evolved and slightly evolved glauconite Condensed section Rim and core of glauconite pellet Mössbauer spectroscopy of glauconite Reverse glauconitization Vermiforms A detailed mineral chemical investigation of glauconite within the condensed section deposits of the Cretaceous Karai Shale Formation, Cauvery Basin, India reflects a wide spectrum in chemical composition related to origin and evolution in different substrates, stratigraphic condensation, and post-depositional alteration. Fe-and Mg-rich glauconite, comprising up to 60% of the sedimentary rocks, occurs as replaced forms of fecal pellets, as infillings within pores and chambers of bioclasts including those of foraminifera, ostracoda, bryozoa, and algae, and as altered forms of mica exhibiting vermiforms. Authigenic precipitation of K-and Fe-poor glauconite, followed by addition of Fe and K into the lattice and concomitant release of Al and Si explains the origin of glau-conite pellets and infillings; the origin of glauconite vermiforms in partly degraded mica involves only the second stage of Fe and K addition. Glauconite pellets and vermiforms exhibit sharply defined alteration zones along peripheries to form rims, and in proximity to cracks or cleavages with reduced K 2 O and Fe 2 O 3 (total) and enhanced Al 2 O 3 and SiO 2 , related to late-stage meteoric water actions. Cores of glauconite pellets and unaltered zones of vermiforms reflect 'evolved' characteristics with N6% K 2 O, typical of a condensed section, while other glauconite varieties occurring at the same stratigraphic level exhibit 'slightly evolved' nature, not consonant with strati-graphic condensation. Increasing abundance of glauconite pellets from the bottom to the top of the transgressive systems tract, accompanied by slight increase in K 2 O within their cores, reflects the effect of stratigraphic condensation on the evolution of glauconite. High Fe 2 O 3 (total) content of glauconite in the Karai Shale Formation may be related to upwelling, although the Fe may be contributed partly by the biotite substrate. Mössbauer spectros-copy of glauconites reveals significant total Fe substitution in both tetrahedral and octahedral sites. Detailed mineral chemical analysis enables us to distinguish stratigraphically significant glauconite within the Karai Shale Formation from the rest of the glauconite notwithstanding its wide compositional range.

In this paper, we re-analyze the ingenious experiment by Kündig (measurement of the transverse Doppler shift by means of the Mössbauer effect) and show that a correct processing of experimental data gives a relative energy shift E/E of... more

In this paper, we re-analyze the ingenious experiment by Kündig (measurement of the transverse Doppler shift by means of the Mössbauer effect) and show that a correct processing of experimental data gives a relative energy shift E/E of the absorption line different from the value of classically assumed relativistic time dilation for a rotating resonant absorber. Namely, instead of the relative energy shift E/E = −(1.0065 ± 0.011)v^2 /2c^2 reported by Kündig (v being the linear velocity of absorber and c being the light velocity in vacuum), we derive from his results E/E = −(1.192 ± 0.011)v^2 /2c^2. We are inclined to think that the revealed deviation of E/E from relativistic prediction cannot be explained by any instrumental error and thus represents a physical effect. In particular, we assume that the energy shift of the absorption resonant line is induced not only by the standard time dilation effect, but also by some additional effect missed at the moment, and related perhaps to the fact that resonant nuclei in the rotating absorber represent a macroscopic quantum system and cannot be considered as freely moving particles.

The Eastern Rhodopes are the main area of distribution of various in color and genesis jaspers in Bulgaria. With the help of Mössbauer spectroscopy and Electron Paramagnetic Resonance (EPR) spectroscopy, the iron status and distribution... more

The Eastern Rhodopes are the main area of distribution of various in color and genesis jaspers in Bulgaria. With the help of Mössbauer spectroscopy and Electron Paramagnetic Resonance (EPR) spectroscopy, the iron status and distribution of different valence states of iron were studied in the three most important impurity phases of jasper – hematite, goethite and celadonite, which are associated with red, yellow to yellowish-brown and green coloration, respectively. In the Mössbauer spectrum of red jasper, Fe 3+ sextets characteristic of hematite and goethite are detected, in the spectrum of yellow jasper – Fe 3+ sextets characteristic only of goethite, and in the green jasper spectrum – dominant Fe 3+ and Fe 2+ doublets associated with celadonite. The EPR spectra of jasper samples reveal information about the concentration of iron-bearing phases and iron ions in tetrahedral coordination.

Coal derived nano-particles has been received much concern recently around the world for their adverse effects on human health and the environment during their utilization. In this investigation the mineral matter present in some... more

Coal derived nano-particles has been received much concern recently around the world for their adverse effects on human health and the environment during their utilization. In this investigation the mineral matter present in some industrially important Indian coals and their ash samples are addressed. Coal and fly ash samples from the coal-based captive power plant in Meghalaya (India) were collected for different characterization and nano-mineralogy studies. An integrated application of advanced characterization techniques such as X-ray diffraction (XRD), High Resolution-Transmission Electron microscopy (HR-TEM)/(Energy Dispersive Spectroscopy) EDS/(selected-area diffraction pattern) SAED, Field Emission-Scanning Electron Microscopy (FE-SEM)/EDS analysis, and Mössbauer spectroscopy were used to know their extent of risks to the human health when present in coal and fly ash. The study has revealed that the coals contain mainly clay minerals, whilst glass fragments, spinel, quartz, and other minerals in lesser quantities were found to be present in the coal fly ash. Fly ash carbons were present as chars. Indian coal fly ash also found to contain nanominerals and ultrafine particles. The coal-fired power plants are observed to be the largest anthropogenic source of Hg emitted to the atmosphere and expected to increase its production in near future years. The Multi Walled Carbon Nano-Tubes (MWCNTs) are detected in our fly ashes, which contains residual carbonaceous matter responsible for the Hg capture/encapsulation. This detailed investigation on the inter-relationship between the minerals present in the samples and their ash components will also be useful for fulfilling the clean coal technology principles.

The copper smelting site S1 in the Eisenerzer Ramsau Valley, Styria, is the largest Bronze Age copper smelting site excavated in the Eastern Alps. The site was almost completely excavated from 1992 to 2006 and ten roasting hearths,... more

The copper smelting site S1 in the Eisenerzer Ramsau
Valley, Styria, is the largest Bronze Age copper smelting
site excavated in the Eastern Alps. The site was almost
completely excavated from 1992 to 2006 and ten roasting
hearths, six double furnaces, a number of pits of
variable size, form and function, and three separate slag
dumps have been recorded. The use of this smelting
site covers the whole period of the Middle Bronze Age
from the 16th to the 13th century BC and might extend
as far as the 11th century BC. The aim of this archaeometallurgical
study is the reconstruction of the smelting
process at this site and the discovery of possible diachronic
changes or developments in the technology of
smelting during the different phases of use. Therefore
slags of the different archaeological phases were analysed
for their chemical and mineralogical composition.
A few slags were analysed with Mössbauer spectroscopy
to obtain further information about the conditions
during the smelting process.
The results of the analyses show that nearly all slags
belong to one particular step of the smelting process
which was the production of raw copper or copper matte
under reducing conditions at temperatures around
1250 °C.

Why is space 3-dimensional? After a brief review of the modern approaches to this query, emphasizing those papers which touched upon epistemological problems, it is stressed that there are two questions which deserve special attention.... more

Why is space 3-dimensional? After a brief review of the modern approaches to this query, emphasizing those papers which touched upon epistemological problems, it is stressed that there are two questions which deserve special attention. They are: the possibility that the large-scale dimensionality of space has been changing in the course of time; and the actual accuracy of the experimental determinations of the dimensionality of space covering a very large scale from the
micro to the macro-cosmos. It is argued in this paper that both Stellar Radiation and the Mössbauer Effect can be used to sketch the answers to these questions.

Magnetic properties of the Mott insulator with the pyrochlore structure Y2Ru2O7 were investigated using Ru99 Mössbauer spectroscopy. Bulk magnetization measurements confirmed appearance of the spin-glass-like antiferromagnetic order with... more

Magnetic properties of the Mott insulator with the pyrochlore structure Y2Ru2O7 were investigated using Ru99 Mössbauer spectroscopy. Bulk magnetization measurements confirmed appearance of the spin-glass-like antiferromagnetic order with very large differences between zero-field-cooled and field-cooled magnetizations below the Néel temperature TN=76(2)K. The Mössbauer spectra were obtained above and below TN. Analysis of the spectrum recorded at 4.2K suggested a noncollinear local ordering of ruthenium magnetic moments. The electronic
structure of the individual ruthenium ion, responsible for magnitudes of hyperfine parameters and the ruthenium magnetic moment, was discussed within the framework of the crystalline electric-field model, including the spin-orbit coupling and the exchange interaction in the molecular-field approximation. Reasonably good agreement between calculated and experimentally determined parameters was obtained. Simultaneously, the experimentally observed easy plane of ruthenium magnetic moments was explained.