Mossbauer Effect Research Articles

Studies of the phase composition and ultrafine structure of the initial domestic raw materials of proppants

The results of the study of intracrystalline electric and magnetic fields in samples on 57Fe nuclei by the ultrafine method of the Mossbauer effect are considered. The source of gamma radiation was 57Co in the chromium matrix. The spectra of the samples were measured on 57Fe nuclei using the MS1104Em spectrometer in the mode of constant accelerations at room temperature for absorption. The crystal structure, phase composition, and electronic states of individual components of the proppants are given. The measurements were carried out on the d8 Advance universal complex (Bruker, Germany). The data of parameters recorded on detectors of secondary energy characteristics of X-rays corresponding to K, L, M, N and O levels of electronic transitions using computer processing of elemental compositions and their ratios in samples are analyzed. The data of X-ray studies of the composition of fly ash are presented, determining its potential application in various industries, including the production of proppants. The results of the analysis of the chemical composition of bauxite samples obtained by X-ray diffraction analysis are presented. The silicon modulus (µSi) has been determined, which is the ratio of Al2O3 to SiO2 to characterize the quality of bauxite. The main components of bauxite were Al2O3 (aluminum oxide) and SiO2 (silicon dioxide). A significant content of Fe2O3 (iron oxide) was also noted, which is 24-33 wt. % for bauxite.

Short-range order in "disordered" aluminum solid solutions in α-iron

The atomic structure of soft magnetic iron-aluminum alloys is studied by X-ray diffraction and nuclear gamma-resonance spectroscopy. The concentration dependence of the body-centered cubic lattice constant and the short-range order (SRO) parameters in the region of a disordered solid solution is monitored. It is shown that in the concentration range from 3 to 18 at.% Al, the lattice constant increases almost linearly. Discrete decomposition of nuclear gamma resonance spectra makes it possible to determine such SRO parameters as the relative fractions of contributions from coordinations without Al atoms and with one, two, and three Al atoms in the first and second coordination shells. The deviation of the values of these fractions from the average statistical probabilities indicates the presence of a chemical order in the arrangement of atoms. The largest deviations are observed at 12 and 15 at.% Al. Conditions of preliminary heat treatment, such as quenching from the paramagnetic state and holding in the ferromagnetic state, give very similar values of the SRO parameters. The method is characterized by a high resolution in the hyperfine field, while having a rather high sensitivity for determining the intensity of individual contributions Keywords: soft magnetic alloys, disordered Fe-Al solid solution, local ordering, X-ray diffraction, Mossbauer effect, distribution of atoms over coordination shells.

MOSSBAUER AND X-RAY FLUORESCENCE STUDIES OF FLY ASH BASED PROPPANTS

This article discusses the results of the study of proppants obtained from domestic raw materials - bauxite, kaolin and white clay, sand, as well as fly ash by nuclear gamma resonance spectroscopy (the Mossbauer effect) and X-ray fluorescence analysis. The hyperfine structure, electronic states and elemental composition of proppants are given. The results of the study of volatile ash obtained during pulverized coal burning of Ekibastuz, Shubarkul, Karazhyralinsky deposits at thermal power plants are analyzed. According to the results of the studies, various combinations of complex phases and the elemental composition of proppants were determined using Mossbauer spectroscopy and X-ray fluorescence analysis. The Mossbauer measurements were carried out on the MS1104Em spectrometer in the constant acceleration mode with a 57Co source in a chromium matrix at room temperature. The elemental composition of samples of proppants based on fly ash was determined using an energy dispersive X-ray fluorescence spectrometer (RFS) at the EDX-7000 installation of SHIMADZU.

The Quantum Motion of the Nerve with a Local Defect

We consider the nerve as the elastic string, the left end of which is fixed at the beginning of the coordinate system, the right end is fixed at point l and mass m is fixed between the ends of the string. We determine the classical and the quantum vibration of such system. The quantum motion is obtained by the so-called non-conventional oscillator quantization method by author. The proposed model can be also related in the modified form to the problem of the Mossbauer effect, being the recoilless nuclear resonance fluorescence, which is the resonant and recoil-free emission and absorption of gamma radiation by atomic nuclei bound in a solid. (Mossbauer,1958). It is not excluded that our oscillator quantization of the string can be extended to generate the new way of the string theory of matter and physiology of nerves.

The phase composition and structure of the BiFeO-=SUB=-3-=/SUB=- film grown on MgO(001) substrate by high frequency cathode deposition in oxygen atmosphere

The crystal structure and Mossbauer spectroscopy studies results for BiFeO3 film growth on the MgO(001) single crystal substrate are present in the paper. It been shown that film have high crystal perfection and low defectiveness which results in appearing of narrow lines during the theta-2theta and φ scanning and the small (lower than 0.7o) disorientation of film and substrate crystal axes. It is been revealed that unit cell of BiFeO3/MgO(001) heterostructure possess monoclinic symmetry and deformation of unit cell is negligible. The Mossbauer study shows that magnetic subsystem of film has spatial spin-modulated structure with zero value of anharmonicity parameter (m). This indicate that at room temperature the magnetic anisotropy changes from the "easy axis" type to "easy plane" type. Keywords: thin films, bismuth ferrite, Mossbauer effect.

Experimental and theoretical investigation of the effect of milling time on the magnetic properties of mechanically alloyed FeAlNi (wt%) powders

Powders of Fe50Al30Ni20 (wt%) are being milled in a P7 high-energy planetary ball mill to determine the effect of milling time on magnetic properties. In order to track changes in morphology and magnetic properties, SEM, magnetic measurements, and Mossbauer spectroscopy were employed during milling. Multiple phases are present; B2-(Fe, Ni)Al dominates, and Fe(Ni, Al) is second in strength. This indicates that they are paramagnetic at room temperature based on the Mossbauer effect spectra after 8 h of milling. The coercivity Hc and saturation magnetization, on the other hand, remains finite values in magnetic measurements. The CASTEP (Cambridge Serial Total Energy Package) code was used to investigate magnetic behavior further.

The Vibration of the String with the Interstitial Massive Point

We will consider the string, the left end of which is fixed at the beginning of the coordinate system, the right end is fixed at point l and mass m is fixed between the ends of the string. We determine the vibration of such system. The proposed model can be also related in the modified form to the problem of the Mossbauer effect, or recoil less nuclear resonance fluorescence, which is the resonant and recoil-free emission and absorption of gamma radiation by atomic nuclei bound in a solid.(Mossbauer,1958)

Effect of lead oxide on the electrical transport properties of lithium–iron–borate glasses

The electrical conductivity and dielectric properties of the glass system (70-x) B2O3–(x) Pb3O4–10Fe2O3–20Li2O [where 0 ≤ x ≤ 35] have been investigated in the temperature range from 300 to 530 K, at four fixed frequencies [0.12, 1, 10, and 100 kHz]. Ac conductivity is found to obey the universal relation, σ(ω) = Aωs, where s is the frequency exponent factor and its value is less than unity. Investigation of σac results and the s factor reveals that the polarons hopping over barrier between Fe2+ and Fe3+ ions is the probable applicable mechanism for σac for these glasses. The dc activation energy values are found to increase from 0.67 to 1.61 eV as the lead oxide content increases. These remarks are explained using Mossbauer Effect (ME) spectrometer and molar volume calculations. The observed higher records of the dielectric constant for the lead-free sample could be attributed to some precipitated iron in the form of α-Fe2O3, which increases the polarized space charges in the glass network.

THE PHYSICAL PHENOMENON OF THE «MÖSSBAUER EFFECT»

In this article, the relevance is the physical phenomenon of the "Mössbauer effect", its application and practical significance for science. The article deals with resonant absorptions of gamma radiation, the history of the discovery of this effect and the experiments conducted by the scientist. The concepts of the decay of the nucleus, the energy of the excited state, and the measurement of energy using this effect are considered. The Mossbauer Effect is an example of a physical phenomenon that has found application in many fields of science: chemistry, nuclear physics, solid-state physics, etc. This work is intended to explain the essence of the Mössbauer effect and to show that the discovery of this effect was of great fundamental and practical importance for science as a whole.

Investigations on microstructure, electrical and magnetic properties of Ni–Zn–Ga spinel ferrites

Two spinel ferrite samples Ni0.7Zn0.3GayFe2–yO4 (y = 0.5, 1.0) were prepared by both ceramic and citrate methods. X-ray diffraction patterns indicated a single phase of cubic structure for all the samples that have a space group Fd-3m. Rietveld analysis using MAUD software for all samples showed that the lattice parameter (a) decreases, while oxygen parameter (U) and strain (ɛ) increase by increasing the amount of Ga. A marked increase in the frequency bands in both the tetrahedral and octahedral sites was observed in the vibrational frequency bands of Fourier transform infrared spectra. Mossbauer effect (ME) spectra recorded at room temperature for the bulk sample (prepared by ceramic method) with lower concentrations of Ga3+ (y = 0.5) consist of two Zeeman sextets. ME spectra for the other bulk sample (y = 1.0) and the two samples in nanoscale (prepared by citrate method) can be fitted by one and two doublets due to the paramagnetic and superparamagnetic behaviour, respectively. Vibrating sample magnetometer measurements showed that the saturation magnetization (Ms) obtained from the hysteresis loop is decreased by increasing Ga3+ concentration for all the samples. The coercivity (Hc) is inversely proportional to the particle size (D) for bulk samples. Nevertheless, Hc of the nanoscale samples enhanced by increasing the particle size. The size dependence of Hc is an indication of the superparamagnetic characteristics supported by ME. The ac electrical conductivity (ln $$ \sigma $$ ), dielectric constant (e′) and dielectric loss tangent (tan δ) were studied at different frequencies and temperatures for the investigated samples. The obtained results showed that the conductivity for all samples increases with increasing temperature in a behaviour similar to that of the most semi-conductor materials.

Mossbauer effect in alloys of variable composition (Tb1-xYx)0.8Sm0.2Fe2

The paper presents the results of studying the Mossbauer effect on alloys of the multicomponent system (Tb1-XYX)0.8Sm0.2Fe2 (substitution parameter X = 0, 0.2, 0.4, 0.6, 0.8, 1). This system is based on the TbFe2 compound, which has a cubic crystal structure and the highest magnetostriction constants among rare-earth intermetallic compounds of the RFe2 type. Substitution of atoms magnetic terbium for weakly magnetic samarium (20%) and nonmagnetic yttrium leads to exchange interactions altering in the system which should affect the magnitude of hyperfine interactions on 57Fe nuclei in alloys of this system. The studies were carried out at room temperature. All parameters of the Mossbauer spectrum being isotropic and anisotropic hyperfine fields, quadrupole shift of the components of the spectrum hyperfine structure, and isomeric shift of the Mossbauer line have been determined. Their dependences on the concentration of yttrium have been established.

Physical principles of the mossbauer effect for solving inner-nuclear phenomena in solids

In this work, using a number of examples, it is shown that one of the promising methods for studying the physicochemical state of matter is Mossbauer spectroscopy with all the variety of its methodological approaches.

Searching for new interactions at submicron scale using the Mössbauer effect

A new technique to search for new scalar and tensor interactions at the sub-micrometer scale is presented. The technique relies on small shifts of nuclear gamma lines produced by the coupling between matter and the nuclei in the source or absorber of a Mossbauer spectrometer. Remarkably, such energy shifts are rather insensitive to electromagnetic interactions that represent the largest background in searches for new forces using atomic matter. This is because nuclei are intrinsically shielded by the electron clouds. Additionally, electromagnetic interactions cause energy shifts by coupling to nuclear moments that are suppressed by the size of the nuclei, while new scalar interactions can directly affect these shifts. Finally, averaging over unpolarized nuclei, further reduces electromagnetic interactions. We discuss several possible configurations, using the traditional Mossbauer effect as well as nuclear resonant absorption driven by synchrotron radiation. For this purpose, we examine the viability of well known Mossbauer nuclides along with more exotic ones that result in substantially narrower resonances. We find that the technique introduced here could substantially improve the sensitivity to a variety of new interactions and could also be used, in conjunction with mechanical force measurements, to corroborate a discovery or explore the new physics that may be behind a discovery.

Valence Transition of EuRh2Si2 Studied by Synchrotron Mössbauer Spectroscopy

We have studied 151Eu Mossbauer effects on EuRh2Si2 at a high pressure of 1.0 GPa as well as at ambient pressure. The compound shows a temperature-induced valence transition from the Eu2+ state to ...

Local properties and phase transitions in Sn doped antiferroelectric PbHfO3 single crystal

Pb(Hf1−xSnx)O3 single crystals with x = 0.23 were characterized using single-crystal x-ray diffraction in the wide temperature range. The information on the structure of two intermediate phases, situated between low temperature antiferroelectric and high temperature paraelectric phases, has been obtained. The lower-temperature intermediate AFE2 phase is characterized by incommensurate displacive modulations in the Pb sublattice. The higher temperature intermediate IM phase is characterized by rotations of oxygen octahedra, primarily in the form of anti-phase tilts, which are also present in the lower-temperature AFE2 phase. For the same crystal, 119Sn Mossbauer effect in the temperature range from 300 K to 600 K has been used to study phase transitions mechanism. Two kinds of quadruple splitting have been found. It implies that two different environments of the central Sn ion exist. The observed two kinds of quadruple splitting do not disappear in the whole investigated temperature range which confirm that even far above TC the structure of paraelectric phase is locally non-centrosymmetric.

Study by Mössbauer-Spectroscopy of Iron Oxides in Acid-Resistant Ceramic Materials Based on Production Waste

The distribution of iron ions during firing of acid-resistant ceramic materials based on production waste is established using the Mossbauer effect. It is revealed that in samples containing an increased amount of iron oxide (17 – 18%) strength and frost resistance are better than in specimens containing 6 – 7 % Fe2O3. Calculation of the areas of the doublets of the spectrum showed that iron compounds at the surface of the samples studied (where an oxidizing atmosphere predominates) are mainly represented by hematite, and in their central part (reducing atmosphere) by magnetite, and in this case specimen acid resistance is reduced.

Mössbauer Studies and Gamma Irradiation Effects on Some Physicochemical Properties of Borophosphate Glasses Doped with Iron Oxide

A series of high iron content boro-phosphate glasses having composition of 30P2O5-70B2O3-xFe2O3);0 ≤ x ≤ 80 wt% was prepared by conventional melt quench method. Mossbauer effect (ME), infrared (IR) and electron spin resonance (ESR) were used to study the behavior of iron brought into borophosphate glass and its effect on the structure of the glass. The results of the glasses containing from 10 to 80 wt% Fe2O3 indicated that iron is present in the glass in the form of Fe3+ and Fe2+, i.e. in tetrahedral and various octahedral symmetric sites. Electron paramagnetic resonance (EPR) spectra were utilized to investigate the glass structure. The analysis shows a well-defined signal at g = 2.04 characteristics for Fe3+ ions and the intensity increases with increasing Fe2O3 concentration before gamma irradiation. After exposing the samples to different doses of gamma irradiation up to 30 kGy; the EPR signal intensity decreases for the samples with a low Fe2O3 concentration (i.e. 10% and 40%), which can be used as radiation indicators. For glass with high iron concentrations above 40%, the intensity of the EPR signal remains approximately constant and therefore, high iron concentrations of this glass can be used for radiation protection purposes.

Neutron diffraction and Mössbauer spectroscopy studies for Ce doped CoFe2O4 nanoparticles

X-ray powder diffraction (XRD), Mössbauer effect (ME) spectroscopy and neutron diffraction (ND) were used to study the structural and magnetic properties of CoFe2-xCexO4 nanoferrites, where (x = 0.0 ≤ 0.1). The lattice parameter (a) and particle size (D) were obtained from Rietveld profile method. The particle size decreased with increasing the Ce content (x). The (ME) spectroscopy confirmed the magnetic order in all the studied samples, with the signature of increasing superparamagnetic contribution by decreasing (D). The cation distribution obtained from the (ME) spectroscopy suggested a partial inverse spinel structure for all the samples and the degree of inversion (δ) was calculated. The (ND) measurements for the samples with (x = 0.0, 0.01 and 0.07) supported the partial inverse spinel structure picture suggested by (ME) spectroscopy. The structure parameters obtained from both (XRD) and (ND) were in agreements.

A Method for Analyzing the Domain Structure in Magnetic Powder Microparticles

A method for analyzing the domain structure in magnetic powder microparticles based on the Mossbauer effect is proposed. This method has been experimentally verified for gadolinium ferrite-garnet (Gd3Fe5O12) powder particles 40 ± 5 μm in diameter in the vicinity of the magnetic compensation point Tcm = 286 K. It is shown that ferrite particles are single-domain near Tcm and pass to the multidomain state while moving away from Tcm.

Mössbauer studies of mixed-valence manganite Pb3(Mn0.965Fe0.035)7O15

Pb3Mn7O15 manganite with mixed valence (Mn3+/Mn4+) was studied by Mossbauer effect on 57Fe impurity atoms in the temperature range of 80–673 K. The experimental spectra consisted of two main quadrupole doublets corresponding to trivalent Fe atoms replacing Mn atoms in different positions in the crystal lattice. Identification of the doublets was made on the basis of calculations of quadrupole splitting within the point charges model and taking possible polarization of oxygen ions into account. In two temperature ranges: T ≈ 370–510 K, corresponding to the structural phase transition, and at T ≈ 140–230 K, where strong anomalies of the magnetic and electrical properties were observed, the sharp changes in the hyperfine quadrupole splitting were observed. It is assumed that these changes are caused by changes in the valence of manganese ions and structural deformations.