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1.
Conversion electron, X-ray backscattering and conventional transmission57Fe Mössbauer measurements have been performed to investigate the origin of the remarkable work hardening at the surface of a high-manganese steel which is called Hadfield steel. Mössbauer results show that α′ martensite has no relation to work hardening. From the comparison of conversion electron to X-ray backscattering spectra, the occurrence of decarbonization is suggested at the surface. The transmission Mössbauer spectrum at 20 K for deformed specimen shows the existence of ε martensite which could be related to the work hardening of Hadfield steel. 相似文献
2.
Polycrystalline Fe2BO4 was prepared by solid state reactions and its electronic and magnetic properties were investigated by Mössbauer spectroscopy and magnetization measurements. The Mössbauer spectra of Fe2BO4 below 270 K indicate the presence of Fe2+ and Fe3+ sites in the structure, in a ratio 1 : 1. Above this temperature electron delocalization sets in between the divalent and trivalent iron ions and Fe2.5+ states are observed. The temperature dependence of the Mössbauer spectra and magnetization measurements clearly show the onset of magnetic order below 155 K. 相似文献
3.
Catherine A. McCammon Donald C. Price 《Journal of Physics and Chemistry of Solids》1982,43(5):431-437
The Mössbauer spectra of (Fe, Co)S1 + x were recorded at room temperature and 4.2 K for samples of varying composition to study the magnetic behaviour of the solid solutions. The Mössbauer spectra are split magnetically at iron concentrations above 16% Fe. For samples with less than 16%Fe, the Mössbauer spectra show no evidence of magnetic splitting down to 4.2 K. The room temperature centre shift data appear to vary continuously with composition and the hyperfine magnetic field decreases with decreasing Fe2+ concentration. A Mössbauer spectrum of 57Fe:CoS at 4.2 K in an external field of 25 kOe showed no evidence of magnetic splitting beyond that caused by the applied field, indicating a net zero internal field.A high spin to low spin transition in Fe2+ is ruled out as being responsible for the observed magnetic behaviour on the basis of the centre shift data. The Mössbauer data are interpreted to indicate a substantial increase in electron delocalization towards the ligands as the 〈M-S〉 distance decreases with decreasing Fe2+concentration. This causes a reduction in the magnitude of the internal magnetic field contributions as well as a decrease of shielding of the nucleus, giving rise to the observed Mössbauer parameters.The Mössbauer spectrum of 57Fe:CoS at room temperature is compared with the spectrum of FeS above the 6.7 GPa phase transition at room temperature. The similarities of the centre shift and the 〈M-S〉 distance in the two phases indicate that covalency may also be responsible for the observed high pressure behaviour of FeS, and not the presence of Fe3+ as was originally suggested. 相似文献
4.
《Current Applied Physics》2015,15(3):417-422
Magnetic and Mössbauer characterization of single crystalline, sub-micron sized Bi2Fe4O9 cubes has been performed using SQUID magnetometry and transmission Mössbauer spectroscopy in the temperature range of 4.2 K ≤ T ≤ 300 K. A broad magnetic phase transition from the paramagnetic to the anti-ferromagnetic state is observed below 250 K, with the Mössbauer spectra exhibiting a superposition of magnetic, collapsed and quadrupolar spectra in the transition region of 200 K < T < 245 K. Room temperature Mössbauer spectra obtained in transmission geometry are identical to those recorded in back-scattering geometry via conversion electron Mössbauer spectroscopy, indicating the absence of strain at the surface. A small hysteresis loop is observed in SQUID measurements at 5 K, attributable to the presence of weak-ferromagnetism arising from the canting of Fe3+ ion sublattices in the antiferromagnetic matrix. 相似文献
5.
The magnetic properties of a sample of synthetic ferrihydrite have been investigated by use of Mössbauer spectroscopy. The area ratios of the Mössbauer lines are not significantly changed by application of magnetic fields at 5 K, indicating an amorphous magnetic structure. An average magnetic moment per particle of 3.1×10?21 JT?1 was estimated from the dependence of the hyperfine splitting of the Mössbauer spectra on external magnetic fields at 80 K. 相似文献
6.
Li Zhe Tong Laixi Liu Xiaohan Ren Liudong Jin Mingzhi Liu Milan 《Hyperfine Interactions》2000,131(1-4):91-102
The Mössbauer spectra of grandidierite and kornerupine at 298 and 90 K were measured. The quadrupole splitting distributions from the Mössbauer spectra were obtained by using the Voigt-based method, and the assignments for QSDs in the Mössbauer spectra of both minerals are presented. Site occupancies of iron in the crystal structures of two minerals were determined, and the chemical formulas of grandidierite and kornerupine were rewritten based on the relative absorption areas and Mössbauer fraction f for Fe3+ and Fe2+. 相似文献
7.
The Mössbauer spectra of the Natural gadolinite and aeschynite at 297K and 81K were measured. The Mössbauer spectrum of the gadolinite consists of one Fe3+ doublet and two Fe2+ doublets, and the multiple Fe2+ doublets in the spectrum of the gadolinite were relating to the next nearest neighbour effect. The Mössbauer spectrum of the aeschynite is composed of one Fe3+ doublet and one Fe2+ doublet, and this result is in agreement with crystal structure determination. 相似文献
8.
D.A. Nolet 《Solid State Communications》1978,28(9):719-722
Mössbauer spectroscopy is used to detect species associated with delocalized electrons undergoing Fe2+ → Fe3+ electron delocation in ilvaite. Mössbauer spectra of a suite of naturally occurring ilvaites were recorded from 80K to 575K and fit to five quadrupole doublets assigned to Fe2+ (A), Fe2+ (B), Fe3+ (A), and Fe2+ (A) → Fe3+ (A)6c and ⊥c. These assignments disagree with earlier interpretations of temperature dependent quadrupole splitting and isomer shift in ilvaite. 相似文献
9.
M. I. Oshtrakh E. V. Petrova V. I. Grokhovsky V. A. Semionkin 《Hyperfine Interactions》2013,222(1-3):61-66
A comparative study of meteoritic olivine in bulk samples of Farmington L5 and Tsarev L5 ordinary chondrites and extracted from Omolon and Seymchan the main-group pallasites was performed using Mössbauer spectroscopy with a high velocity resolution. Mössbauer spectra for each specimen were measured at 295 and 90 K. Mössbauer spectral components related to the 57Fe in crystallographically non-equivalent sites M1 and M2 in olivines were determined and their Mössbauer hyperfine parameters were evaluated. It was found small variations of quadrupole splitting for the 57Fe in both the M1 and M2 sites of olivines in bulk ordinary chondrites and olivines extracted from pallasites. 相似文献
10.
Glycerol forms a molecular glass near 180K. Fe2+ dissolved in glycerol allows the study of the dynamics of the system by Mössbauer spectroscopy. Recently it has been shown that the Mössbauer spectra can be understood in a way consistent with the results of dielectric and ultrasonic viscoelastic relaxation measurements. A jump diffusion model of Sinqwi and Sjolander with a jump rate distribution according to Davidson and Cole allowed us to fit the Mössbauer spectra of Fe in glycerol. First attempts to compare mode coupling theory with Mössbauer spectra are reported. 相似文献
11.
S. Jha D. Suyanto C. Mitros G. Stroink Z. M. Stadnik R. A. Dunlap G. M. Julian 《Hyperfine Interactions》1990,55(1-4):1317-1321
Split source57Fe Mössbauer effect spectroscopy has been performed between 4 K and 295 K on the superconducting perovskite GdBa2Cu3O7?y. No evidence is seen for magnetic splitting at low temperatures as reported in some split absorder57Fe Mössbauer experiments on this material. There is evidence for phonon mode softening, as observed for119Sn Mössbauer spectra of some other highT c superconductors. 相似文献
12.
E. Kuzmann K. Nomura M. El-Sharif C.U. Chisholm G. Principi C. Tosello R. Gupta K. Havancsak A. Vértes 《Hyperfine Interactions》1998,112(1-4):175-178
Electrodeposited Fe-Ni-Cr alloys irradiated with 209 MeV energy 84Kr ions were investigated by conversion electron Mössbauer spectroscopy, X-ray diffraction and electron microprobe analysis. Significant dose dependent changes were found between Mössbauer spectra of the irradiated and non-irradiated deposits. These changes reflect the dose dependent transformation of the metastable ferromagnetic phase to the paramagnetic one. 相似文献
13.
Arũnas Amulevičius Kęstutis Mažeika Vidmantas Remeikis Algimantas Undzėnas 《Central European Journal of Physics》2007,5(2):135-150
57Fe isotope-enriched iron phthalocyanine has been synthesized and studied by the Mössbauer spectroscopic method. The samples were investigated in the temperature range 100–350 K. Some peculiarities in atomic and molecular electronic structure fluctuations were observed. The intermediate Fe oxidation states are observed and it has been found that the rate of charge redistribution is temperature-dependent. The correlation between the temperature behavior of the isomeric shift and quadrupole splitting has been demonstrated. At elevated temperatures above 300 K, the Fe2+ oxidation number is quasistable. The alteration of Fe oxidation number is associated with fluctuations of electron charges, and the electron-accepting and electron-donating properties of surrounding ligands. The energy barriers separating Fe oxidation states have been determined. The possibility of modeling Mössbauer spectra of electron-transfer systems has been shown. 相似文献
14.
D. G. Patrusheva M. I. Oshtrakh E. V. Petrova V. I. Grokhovsky V. A. Semionkin 《Hyperfine Interactions》2010,197(1-3):295-300
Study of olivine (Fe, Mg)2SiO4 from Omolon meteorite was performed using Mössbauer spectroscopy with a high velocity resolution at 295 and 90 K. Components related to 57Fe in crystallographically non-equivalent M1 and M2 sites in olivine were determined and its Mössbauer hyperfine parameters were evaluated at both temperatures. A Fe2?+?–Mg2?+? distribution coefficient and a temperature of cation equilibrium distribution for olivine from Omolon were evaluated on the basis of Mössbauer parameters. 相似文献
15.
Mössbauer studies have been performed on FePS3 in powder form between 125 K and 450 K. The Mössbauer spectrum consists of an asymmetric doublet, ratio~0.93 at room temperature. The asymmetry is attributed to the Goldanskii-Karyagin effect and the lattice anisotropy is found to be ~1.4, with the largest vibrations parallel to thec ? axis of the monoclinic unit cell. The Debye temperature is ~200 K. 相似文献
16.
E. Kuzmann Z. Homonnay K. Kovács P. Zsabka A. Erőss J. Mádl-Szőnyi 《Hyperfine Interactions》2014,226(1-3):571-577
Biofilms formed at spring caves of Buda Karst, Hungary, were investigated by 57Fe Mössbauer spectroscopy. 78 K Mössbauer spectra were decomposed into a sextet and two doublets. The subspectra were assigned to goethite, hematite, ferrihydrite and siderite, according to their known Mössbauer parameters. The room temperature spectra indicated that goethite and/or hematite are in the superparamagnetic state at room temperature. The results can be interpreted in terms of karstification of hypogenic caves by the role of biofilms via discharge features. 相似文献
17.
Recent investigations claimed the complete amorphization of elemental FeZr multilayer films by solid state reaction during vacuum annealing. In the present study it is established by57Fe conversion electron Mössbauer spectroscopy (CEMS) that annealing under ultrahigh vacuum conditions does not lead to complete amorphization: only a maximum thickness of ≈14 Å interfacial α-Fe is transfered into the amorphous phase between 620–660 K. This thin amorphous layer apparently acts as a diffusion barrier and prohibits further growth of the amorphous phase. The average composition of the amorphous interfacial layer was determined from the Mössbauer spectral parameters. 相似文献
18.
Jan Chojcan 《Hyperfine Interactions》2006,168(1-3):1109-1114
The Mössbauer spectra of 57Fe were measured for the thermal equilibrium b.c.c. Fe0.947V0.053 and Fe0.956Co0.044 solid solutions being at temperature ranging from 300 to 1,000 K. The obtained data were analysed in terms of concentration of unoccupied sites in the 14-site surroundings of an 57Fe Mössbauer probe in a b.c.c. sample. It turned out that the probe detects unoccupied sites in its neighbourhood when the temperature of the material studied does not exceed about 900 K. This result suggests that the Mössbauer spectroscopy “sees” the pre-vacancy effect revealed by the positron annihilation spectroscopy in the early 1960s. 相似文献
19.
I. König H. -D. Knauth Chr Koopmann F. E. Wagner U. Wagner 《Hyperfine Interactions》1988,41(1):811-814
In Mössbauer spectra of freeze-dried as well as air-dried anoxic Elbe sediments, about 40% of the Fe2+ is converted to Fe3+ compared to the undried material measured under anoxic conditions. RT spectra of material annealed at increasing temperatures and Mössbauer studies at 4.2 and 1.8 K serve to discriminate between structural and oxidic Fe3+. 相似文献
20.
《Physics letters. A》1988,126(7):439-443
Using the high-resolution 93.3 keV Mössbauer transition in 67Zn we studied the temperature dependence of the center shift in ZnO single crystals between 4.2 and 77.3 K. Already at low temperature dependent isomer shift is present. The latter originates from phonon-induced electron transfer from zinc to oxygen 相似文献