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1.
I. Dézsi R. Coussement S. Fehér G. Langouche Cs. Fetzer 《Hyperfine Interactions》1986,29(1-4):1275-1278
Single crystals of α-Al2O3 and LiNbO3 were implanted with57Co (dose: up to 2×1015 atoms/cm2) and with57Fe (dose: 2×1015 atoms/cm2) ions. The Mössbauer spectra revealed the disordered atomic environment. Fe2+ and Fe3+ charge states were observed. The spectra were compared to the spectra of crystals doped with57Co. It was remarkable that in the doped α-Al2O3 Fe3+ states with slow spin-spin relaxation have appeared. The CEMS study of the samples implanted with57Fe resulted in Fe2+ ionic states indicating that a fraction of Co atoms can also be in Co2+ state. 相似文献
2.
57Fe ion implanted chromium foils have been analyzed by conversion electron Mössbauer spectroscopy. After annealing at temperatures up to 600 °C, the CEM spectra show two magnetic components which are attributed to iron atoms in the core and the outer layer of grains. By means of a simple model using the spectral data, the final average iron grain has been evaluated to be about 5 nm. 相似文献
3.
J. Kowalski J. Stanek T. Tyliszczak B. D. Sawicka J. A. Sawicki M. Drwiega 《Hyperfine Interactions》1983,15(1-4):499-502
Thermal annealing effects in lithium fluoride single crystals implanted with57Fe ions were studied by conversion electron Mössbauer spectroscopy. It was found that annealing in vacuum leads mostly to the precipitation of metallic aggregates in contrast to the annealing in He and H2 when the formation of ferric compounds, having high magnetic transition temperatures, takes place. 相似文献
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5.
Fe implanted SnO2 films (5 × 1016 and 1 × 1017 57Fe ions/cm2) characterized by conversion electron Mossbauer spectroscopy (CEMS) are reviewed. The substrate temperatures affect the growth of precipitated iron oxides. The Fe ion implanted film at room temperature (RT) shows no Kerr effect and no magnetic sextet in CEM spectra. The SnO2 film implanted with 57Fe at the substrate temperature of 300 °C show a small Kerr effect although the magnetic sextet is not observed, but post-annealing results in the disappearance of the Kerr effect. This magnetism is considered to be due to defect induced magnetism. Some samples were measured by CEMS at 15 K. SnO2 (0.1 at %Sb and 3 at %Sb) films, implanted at 500 °C and the post-annealed samples, show RT ferromagnetism due to formation of clusters of magnetite and maghemite, respectively. The layer by layer analysis of these films within 100 nm in thickness has been done by depth sensitive CEMS (DCEMS) using a He + 5 % CH4 gas counter. The structures and compositions of Fe implanted SnO2 films, and the effects due to post-annealing were investigated. 相似文献
6.
57Fe implanted and post Al implanted in aluminum foil have been performed at low energy of 27keV and the CEMS shows the formation
of intermetallic compounds FeAlσ and Fe2Alσ during the ion bombardment. The results are discussed with the enhanced diffusion by energetic ion bombardment. 相似文献
7.
H. P. Gunnlaugsson K. Nomura T. E. Mølholt S. Shayestehaminzadeh K. Johnston R. Mantovan H. Masenda M. Ncube K. Bharuth-Ram H. Gislason G. Langouche D. Naidoo S. Ólafsson G. Weyer 《Hyperfine Interactions》2014,226(1-3):389-396
States of dilute Fe in SnO2 have been monitored using 57Fe emission Mössbauer spectroscopy following implantation of 57Mn (T 1/2 = 85.4 s) in the temperature range from 143 K to 711 K. A sharp annealing stage is observed at ~330 K where the Fe3?+?/Fe2?+? ratio shows a marked increase. It is suggested that this annealing stage is due to the dissociation of Mn-VO pairs during the lifetime of 57Mn; the activation energy for this dissociation is estimated to be 0.9(1) eV. Fe3?+? is found in a paramagnetic state showing spin-lattice relaxation rates consistent with an expected T 2 dependence derived for a Raman process. In addition, a sharp lined doublet in the Mössbauer spectra is interpreted as due to recoil produced interstitial Fe. 相似文献
8.
A new type of CEM-spectrometer allows in situ measurements on metal foils implanted at low temperatures. It has been used
to study defect association and clustering of57Fe in Al and Cu. For57FeAl, the substitutional fraction (f
s) in samples implanted at 120 K is somewhat smaller than expected for a random impurity distribution but much larger than
after room temperature implantation. For57FeCu,f
s for samples implanted at 120 K is less than 0.5 of the value expected for a random distribution and it falls to zero after
annealing at 600 K, where more extensive Fe clustering occurs. Vacancy trapping in stage III does not contribute significantly
to the observed defect sites. 相似文献
9.
Mossbauer spectroscopy, RBS and Infrared absorbed spectroscopy (IAS) analysis were carried out for the single crystal Si and
amorphous Si both implanted by57Fe. Mossbauer spectra were fitted by separated and continuous spectrum for single crystal Si and amorphous Si, respectively.
Some interesting information of the chemical characteristics around the implanted ions were obtained. 相似文献
10.
Amorphous layers produced at the surface of iron by B+ and C+ implantation (50 kV, 1×1018 ions cm−2) were analyzed by CEMS. The CEM spectrum of B+ implanted layer was composed of broad doublet and sextet. Spread hyperfine field distribution, P(H), indicates the formation
of extremely disordered FeB layer. Annealing at 400°C brought about precipitation of FeB, which was converted to Fe2B by annealing at 500°C.
The P(H) for C+ implanted iron was resolved to 3 subpeaks with H values of 11.0, 18.0 and 22.5 T. The amorphous FeC phase was strongly correlated
to crystalline Fe5C2 and Fe2C, which precipitated at 300°C and were transformed into Fe3C at 500°C. The amorphous layer disappeared by annealing at 600°C. 相似文献
11.
Mossbauer studies were performed in 57Fe impurities (0.3% at.) in solid methane, in order to investigate the properties of the order-disorder phase transition taking place at Tc=20.4K. From the temperature dependence of the relative values of the recoil-free-fraction - f - it was found that near Tc a change occurs in the slope of f(T2) without discontinuity in the value of f. A consistent model is proposed by which immediately below Tc both phases, I and II coexist with a gradual evolution of the ordered state (II) on the account of the high temperature plastic state (I). The Debye temperature of phase II (θII = 101±7K) increases with respect to that of phase I (θI = 72±3K), indicating a hardening in the phonon spectrum and precluding the onset of rotational modes of the disordered molecules. 相似文献
12.
Existing values of the conversion coefficient of the 14.4 keV transition in57Fe have been reevaluated using newK-shell fluorescence yields and recent decay scheme information. Previous disagreements are removed and the mean values found are α T =8.26±0.19, α K =7.37±0.17. 相似文献
13.
Transient Mössbauer experiments with57Fe are described. A time resolution of 0.7 ns is achieved with a BaF2 scintillator. Polar polyvinylidene fluoride film is shown to be well suited for producing fast mechanical modulation. Pulses of recoilless gamma radiation, of width ≈30 ns and heigth 3.5 times the Mössbauer absorption, are generated with stepwise source motion. The efficiency of transient methods in extracting Mössbauer data is demonstrated with sinusoidal motion. 相似文献
14.
57Co was implanted in different reactive and non reactive frozen gases like Ne, Ar, N2, Xe, CH4 and C2H4. Higher ionization states of Fe and cryochemical compounds are detected. 相似文献
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16.
The properties of the negative parity states of55Fe and57Fe are investigated in the framework of the intermediate coupling model. In the model, a neutron or a quasineutron is coupled to anharmonic vibrations of the core. Anharmonicities of the vibrations are estimated through the observed properties of the core. Energy levels, spectroscopic factors and electromagnetic properties have been calculated. The results of the present calculations are also compared with available experimental results and other theoretical results. The model reasonably accounts for many of the properties of the low-lying states. 相似文献
17.
Conclusions Different charge states of57Fe are identified in the57Co implanted SiO2 matrix.It is interesting to see that the states appearing in solid oxygen [2 ] also appear in the SiO2 matrix, although in neither of the matrices a preferential interpretation of the S1-line being Fe+ 6 or Fe0, can be achieved.Further, implantation of57Fe in SiO2 could reveal whether the states appearing in the57Co implanted SiO2 are really after decay effects or part of a (57Fe-SiO2)-structure.The authors wish to thank Prof. P. Boolchand for the SiO2 samples and L. Verwilst for the ion implantation. 相似文献
18.
Y. Kobayashi H. Nonaka J. Miyazaki M. K. Kubo H. Ueno A. Yoshimi H. Miyoshi D. Kameda K. Shimada D. Nagae K. Asahi Y. Yamada 《Hyperfine Interactions》2005,166(1-4):357-361
The in-beam Mössbauer spectroscopy using a short-lived 57Mn (T 1/2=1.5 min) beam was carried out to study the production of the exotic chemical species of 57Fe atoms arising from 57Mn implanted into solid oxygen. The obtained spectra can be analyzed by four components of doublets at least, which are assigned to be novel Fe species of FeO, Fe(O2), (O2)FeO2, and Fe(O2)2, on the basis of ab initio molecular orbital calculations. 相似文献
19.
Jan Stanek 《Hyperfine Interactions》1986,29(1-4):1245-1248
The thermal evolution of the local states of the Fe-impurity ions introduced by implantation to the enstatite lattice was studied by Conversion electron Mössbauer Spectroscopy. The obtained results are discussed in terms of thermodynamical properties of pyroxenes and compared with lunar samples data. 相似文献
20.
In UHV-applications of DCEMS or ICEMS the optimization of the experimental performance is of utmost importance. For the characterization of the “statistical quality” of the Mössbauer-effect experiment, the statistical utility rateu is defined. The measuring time gain valuesG are determined by comparing values ofu. It is shown with57Fe DCEMS and UHV ICEMS measurements performed on various57Fe samples applying a channeltron and an extremely low-noise scintillation e?-counter as electron detector that preferable experimental conditions for ICEMS and DCEMS measurements are different. 相似文献