119Sn Atoms Research Articles

Mapping the magnetic hyperfine field in GdCo5

The magnetic hyperfine field (Bhf) in ferrimagnetic GdCo5 compound has been investigated as a function of temperature by Mössbauer effect (ME) spectroscopy and perturbed angular correlation (PAC) spectroscopy using 119Sn and 111Cd probe nuclei, respectively. Results show that the non-magnetic probe atoms 119Sn and 111Cd substitute all three non-equivalent positions in GdCo5: Gd, CoI, and CoII. For 119Sn and 111Cd probes at Gd sites, the saturation magnetic hyperfine fields are very different with values of Bhf1 = 57.0(1) T and Bhf1= 20.7(1) T, respectively. For 119Sn and 111Cd atoms localized at CoI and CoII sites the magnetic hyperfine fields are practically identical and, in saturation, reach the values of Bhf2 = 11.6(1) T and Bhf2 = 11.1(2) T, and Bhf3 = 14.8(1) T and Bhf3 = 14.4(2) T, respectively.

The state of tin impurity atoms in vitreous germanium chalcogenides

Tin atoms formed after the radioactive decay of the 119mmSn and 119Sb impurity atoms in the structure of GexS1 − x and GexSe1 − x glasses are stabilized in the form of Sn2+ and Sn4+ centers or in germanium nodes (after 119mmSn decay), or in the nodes of structural units formed by 119Sb atoms. The Sn2+ and Sn4+ centers correspond to the ionized states of amphoteric two-electron tin center with negative correlation energy. 119Sn atoms formed after the radioactive decay of the 119mTe atoms in the structure of GexS1 − x and GexSe1 − x glasses are stabilized in both chalcogen and germanium nodes.

Tin impurity centers in glassy germanium chalcogenides

Tin atoms produced by radioactive decay of 119mmSn and 119Sn impurity atoms in the structure of GexS1 − x and GexSe1 − x glasses are stabilized in the form of Sn2+ and Sn4+ ions and correspond to ionized states of the amphoteric two-electron center with negative correlation energy (Sn2+ is an ionized acceptor, and Sn4+ is an ionized donor), whereas the neutral state of the Sn3+ center appears to be unstable. 119Sn atoms produced by radioactive decay of 119mTe impurity atoms in the structure of GexS1 − x and GexSe1 − x glasses are stabilized at both chalcogen sites (they are electrically inactive) and germanium sites.

Impurity centers of tin in glassy arsenic chalcogenides

119Sn atoms produced by radioactive decay of 119Sb impurity atoms in the structure of AsxS1 − x and AsxSe1 − x glasses are stabilized in the form of Sn2+ and Sn4+ ions at arsenic sites and correspond to ionized states of the amphoteric two-electron center with negative correlation energy (Sn2+ is an ionized acceptor, and Sn4+ is an ionized donor), whereas the neutral state of the Sn3+ center is unstable. The fraction of Sn4+ states increases with chalcogen content in glass. 119Sn atoms produced by radioactive decay of 119mTe impurity atoms in the structure of AsxS1 − x and AsxSe1 − x glasses are stabilized at chalcogen sites (they are electrically inactive) and arsenic sites, and the fraction of arsenic atoms decreases with the chalcogen content in glass.

Hyperfine magnetic fields at the nuclei of probe 119Sn atoms and exchange interactions in the CaCu3Mn3.96Sn0.04O12 manganite

We have investigated the hyperfine magnetic interactions between the nuclei of probe 119Sn atoms in the CaCu3Mn3.96Sn0.04O12 double manganite by Mossbauer spectroscopy using magnetic measurements. A consistent description of the results obtained in terms of the Weiss molecular field model by taking into account the peculiarities of the local environment of tin atoms has allowed the indirect Cu2+-O-Mn4+ (JCuMn ≈ −51 ± 1 K) and Mn4+-O-Mn4+ (JMnMn ≈ −0.6 ± 0.6 K) exchange interaction integrals to be estimated. Based on the Kanamori-Goodenough-Anderson model, we show that the magnitude and sign of the intrasublattice exchange integral JMnMn correspond to both the electronic configuration of the Mn4+ cations and the geometry of their local crystallographic environment in the compound under study.

Mössbauer study of compounds of Cu3 − x Fe x SnS4 and Cu2Fe1 −x Zn x SnS4 systems

A Mossbauer study of the structural and charge states of 57Fe and 119Sn atoms in the compounds of Cu3 −xFexSnS4 and Cu2Fe1 − xZnxSnS4 systems was performed. It was shown that the iron atoms in the compounds of both systems were in the divalent and trivalent states occupying the tetrahedral positions of the structure. The character of the changes of the degree of covalency of the Fe2+-S, Fe3+-S and Sn4+-S bonds during the isomorphic substitution in the systems was established.

Magnetic hyperfine interactions of 119Sn probe atoms in the binary perovskite CaCu3Mn4O12

The manganite CaCu3Mn4O12 doped by 119Sn atoms (about 1 at % with respect to Mn atoms) is studied by Mossbauer spectroscopy. The introduction of diamagnetic tin atoms is found not to affect the structure of the manganite. Tetravalent tin atoms are shown to substitute for the isovalent manganese atoms that are located in an octahedral oxygen surrounding. The cluster method of molecular orbitals is used to calculate the contributions of Mn4+ and Cu2+ cations that belong to different structural sublattices to the hyperfine magnetic field at 119Sn nuclei (HSn = 105 kOe at T = 77 K). These partial contributions are analyzed, and the intrasublattice Mn4+-O-Mn4+ exchange interactions are found to play a significant role in the formation of the magnetic structure of the manganite.

Depth-selective measurements of induced magnetic polarization in Cu layers of Gd/Cu multilayersby 119Sn Mössbauer spectroscopy

We performed 119Sn Mössbauer spectroscopic measurements on Gd/Cu multilayers with119Sn probing atoms. The Cu layers are delta-doped with Sn probes at a certain depth. Hyperfinefields are observed in the Mössbauer spectra at low temperatures below the Curietemperature of the Gd layers. From the temperature-dependent measurements, thehyperfine field is found to be proportional to the spontaneous magnetization ofthe Gd layer. The result indicates that the Gd magnetization induces magneticpolarization in the Cu layers. The hyperfine field per Gd magnetization is found to be∼40 kOe /μB(Gd), regardless of theposition of the 119Sn atoms and the Cu thickness (20–40 Å), suggesting that the magnetic polarization in the Culayer is uniform at any depth from the Gd/Cu interface.

Local structure and hyperfine interactions of 57Fe and 119Sn atoms in brownmillerite-like ferrite Sr2Fe1.98Sn0.02O5+x

Mössbauer spectroscopy has been applied for studying local environment of 57Fe and 119Sn probe atoms within tin-doped Sr2Fe1.98Sn0.02O5+x (x⩽0.02) ferrite with the brownmillerite-type structure. 57Fe Mössbauer spectra indicate no appreciable local distortions induced by the tin dopant atoms. The 119Sn spectra recorded below the magnetic ordering temperature (TN) can be described as a superposition of two Zeeman sextets, which indicate that Sn4+ dopant ions are located in two non-equivalent crystallographic and magnetic sites. The observed hyperfine parameters were discussed supposing Sn4+ cations to replace iron cations in the octahedral (SnO) and tetrahedral (SnT) sublattices. It has been supposed that Sn4+ cations being stabilized in the tetrahedral sublattice complete their nearest anion surrounding up to the octahedral oxygen coordination “SnT4+”. Annealing of the Sr2Fe1.98Sn0.02O5+x in helium flux conditions at 950°C leads to formation of divalent Sn2+ cations with a simultaneous decrease of the contribution for the SnT4+ sub-spectrum. The parameters of combined electric and magnetic hyperfine interactions of the 119Sn2+ sub-spectrum underline that impurity atoms are stabilized in the sp3d-hybrid state in the oxygen distorted tetragonal pyramid. The analysis of the 119Sn spectra indicates a chemical reversibility of the processes SnT2+⇌SnT4+ within the tetrahedral sublattice of the brownmillerite-type ferrite.

Mössbauer-effect study of competitive exchange interactions in UNi 1− xCo xGa solid solutions

Results of Mössbauer spectroscopy of 119Sn atoms substituted on Ga sites in the UNi 1− x Co x Ga solid solutions are presented and discussed together with previously reported magnetization data in terms of evolution of magnetism between the antiferromagnet UNiGa and ferromagnet UCoGa. The Mössbauer spectra were analyzed by considering the hyperfine field transferred to the 119Sn nucleus from the six nearest U magnetic moments and a weak signal due to anisotropic polarization of Sn 5p states. The low-temperature spectra for UNiGa and UCoGa are consistent with their ground-state magnetic structures. The nonmagnetic component observed for UNiGa persists in the spectra for x up to 0.4 which indicates the presence of antiferromagnetically coupled U moments. The nonmagnetic component emerging in the spectra for x around 0.77 is tentatively attributed to clusters of frustrated U magnetic moments surrounding the 119Sn nuclei.

Local environment and vibrational characteristics of 119Sn(II) Mössbauer probe atoms located on the surface of Cr 2O 3 microcrystals

Two different sites have been evidenced for SN(II) dopant atoms located at the surface of the Cr 2O 3 substrate. Their inequivalence appears to be essentially due to the number of neighboring Cr(III) cations which are responsible for the magnetic hyperfine fields H transferred at the 119Sn nuclei. While a large difference is observed in the saturation values of H, the isomer shift and quadrupole splitting—which are predominantly determined by tin-oxygen bonding—differ for the two sites to a lesser extent. Moreover, the main component V zz of the electric field gradient at 119Sn nuclei is found, in both cases, to be negative and oriented at the same angle with respect to the c-axis of the Cr 2O 3 lattice. The magnetic ordering temperature detected by the surface-located 119Sn(II) atoms appears to be in good agreement with that previously determined from antiferromagnetic resonance experiments for undoped Cr 2O 3. The Goldanskii-Karyagin effect, which is observed for Sn(II) dopant atoms in the paramagnetic region, indicates that the mean square vibration amplitudes are smaller along the V zz axis than perpendicular to this direction.

Mössbauer Emission Spectra of 119Sn in Binary Compounds of Antimony and Tellurium

Abstract The Mössbauer emission spectra of defect 119Sn atoms arising from 119Sb and 119mTe were measured in GaSb, InSb, In2Te3, ZnSb, CdSb, CdTe, and Ag2Te. The lattice sites of defect 119Sn atoms in these binary compounds were determined on the basis of the obtained Mössbauer parameters and the recoil energy associated with EC decays of the source nuclides. Together with the results of previous studies, the isomer shifts of both defect and normal 119Sn were shown to correlate with the electronegativitity of ligands in binary compounds of the main-group elements, such as Sn, Sb, and Te.

57Fe and 119Sn mössbauer spectrometry studies on nanocrystalline FeSn solid solutions

Fe 1−xSn x (0.04 ≤ × ≤ 0.124) solid solutions with nanometer-sized grains were prepared by mechanical alloying. Broad spectral components are ascribed to Fe and Sn atoms at grain boundaries (GB) of the as-milled materials. The mean hyperfine fields at the nuclei of atoms at GB are smaller than they are for atoms in grains. By measuring the grain size and the fraction of atoms at grain boundaries, the effective thicknesses of the grain boundaries could be estimated to be ∼ 1 nm. Previously-reported Mössbauer spectra of 119Sn atoms at GB of coarse-grained iron are discussed.

The interaction between 119Sn and solute atoms dissolved in iron; the case of beryllium alloy

Be is a small atom (V=4.89 cm3 mol-1) compared with Fe and Sn (V=7.09 and 16.30 cm3 mol-1 respectively). As a result, size mismatch theories predict an attractive component of the potential between Be and Sn when dissolved in iron. The author presents spectra of 119Sn in a FeBe alloy, from which he deduces repulsive interactions at first- and second-neighbour distances. The first-neighbour interaction is in fair agreement with the semi-empirical theory of Miedema and Krolas. The repulsive interaction at the second-neighbour distance contradicts the expectation developed in earlier papers. He also makes some comments on the influence of solute-solute interactions on the deduction of probe-solute interaction potentials.

Synthesis, Raman and NMR spectroscopy of the trimetallic complexes [IrCl(SnCl 3)(HgCl)(CO)(PR 3) 2

Synthesis, Raman and NMR studies are presented for the new octahedral trimetallic complexes with composition [IrCl(SnCl 3)(HgCl)(CO)(PR 3) 2], R = p-XC 6H 4; X = H, CH 3O, F, Cl. Only the isomer containing the Cl 3SnIrHgCl fragment and trans phosphine ligands is observed. Force constants for the IrSn and IrHg bonds as well as 31P, 119Sn and 199Hg NMR data are reported. The presence of a spin-spin coupling constant of more than 40,000 Hz between the 199Hg and 119Sn atoms is shown to originate from a two-bond and not a one-bond interaction.

The binding of tin atoms to ammonia: A mössbauer study

Mössbauer studies were performed with 119Sn atoms embedded in solid NH 3 in the temperature range 14–80 K. The quadrupole-split spectrum with AΔ E Q = 2.72(2) mm/s and isomer shift = +2.52(2) mm/s with respect to BaSnO 3 indicates formation of a singly bound, covalent SnNH 3 molecule. From the temperature dependence of the recoil-free fraction, its force constant in sohd ammonia is derived.

Mössbauer emission studies of defect 119Sn, 119Sb, and 119mTe atoms after nuclear decays and reactions in SnSb, SnTe, and Sb2Te3

119Sn-Mössbauer emission spectra of Sn119Sb, Sn119mTe and Sb2 119mTe3 were measured. Defect 119Sn atoms occupying the lattice sites of Sb and Te in the matrices were identified from the isomer shifts of the emission lines. The isomer shifts of normal and defect 119Sn were found to correlate with the electronegativities of the nearest neighbor atoms in metals and the binary compounds of Sn, Sb, and Te. These results were utilized to estimate the final state of energetic 119Sb and 119mTe after p and α reactions in SnSb and SnTe. The recoil atoms were found in scarcely perturbed lattice points. Their distribution in the lattice was as expected from the electronegativities of the recoil atoms and the lattice components. In SnTe the effect of Sn vacancies on the fate of recoil 119Sb was studied.

Molecular dynamics of adducts of organotin(IV) and tin(IV) chlorides with NN′-ethylenebis(salicylideneimine) studied by temperature-dependent Mössbauer spectroscopy

Lattice dynamics studies have been carried out on the solid-state polymers (SnRnCl4–n·H2salen)x(H2salen =NN′-ethylenebis(salicylideneimine); n= 2, R = Me or Ph; n= 1, R = Me, Bun, n-octyl, or Ph; n= 0), as well as on the monomeric complex SnMe2(salen), by temperature-dependent Mossbauer spectroscopy. The functions In A(T), In fa(T), and 〈x2〉(T) are linear for adducts with n= 0–2 and R = Me or Ph, but are perceptibly nonlinear for the remaining compounds, suggesting motional anharmonicity of 119Sn atoms in the latter. Compounds characterized by linear functions form two distinct homologous series (n= 2, n= 0 or 1) where a general decrease of the parameters θD and [graphic omitted]D takes place in parallel to an increase of the vibrating mass. The results are discussed in relation to the vibrating mass model, and to previous investigations. The characteristics of the anharmonic derivatives are tentatively interpreted in terms of progressive structural changes to to form monomers.

Mössbauer spectroscopic verification of two different states of impurity 119Sn atoms in Sb 2Te 3

The 119Sn atoms arising in Sb 2 119 mTe 3 give a Mössbauer emission line with an isomer shift close to that of SnSb, while the isomer shift of the 119Sn arising in 119Sb 2Te 3 is close to that of SnTe.

Mössbauer Effect of 57Fe and 119Sn Atoms Isolated in Solid Nitrogen

The Mössbauer resonances of nitrogen-matrix-isolated 57Fe and 119Sn atoms have isomer shifts, which are within the experimental errors, identical with the isomer shifts of the same atoms isolated in rare-gas matrices. Despite an observed quadrupole splitting of the 57Fe and 119Sn resonances, the relatively small photoelectric cross section of nitrogen makes the nitrogen matrix useful for matrix-isolation Mössbauer studies of nuclei which require relatively thick Mössbauer absorbers.