BaSnF4 fast ion conductor: Variations versus the method of preparation and anomalous temperature variation of the quadrupole splitting

A new method of preparation of high performance fluoride ion conductor, BaSnF₄, by water leaching of newly discovered barium tin(II) chloride fluorides, has been designed, and the materials have been studied and compared to the solid prepared by the usual dry method. The unit-cell parameters and crystallite dimensions were found to vary with the method of preparation. In addition, the crystallite dimensions were found to be highly anisotropic for the samples obtained by the wet method. The Mössbauer spectrum is made of a large tin(II) quadrupole doublet, and a broad tin(IV) oxide peak due to surface oxidation. The tin(II) spectrum is in agreement with covalently bonded tin(II) having a strongly stereoactive lone pair. An unusually high dependence of the quadrupole splitting at low temperatures was observed (5.8 times larger than for α-SnF₂).     

Phase transition of the doubly disordered Ba1−x Sn x Cl1+y F1−y solid solution at high temperature

The Ba_1−x Sn _x Cl_1+y F_1−y solid solution has the BaClF structure, with full disorder of the cations and partial disorder of the anions. It can be prepared either by the wet method or the dry method. Most samples prepared by the aqueous route give a tin(II) single line at ca. 4.1 mm/s characteristic of the Sn²⁺ stannous ion, and therefore of ionic bonding. In some rare cases, a very weak quadrupole doublet indicates the presence of a small amount of covalently bonded tin(II). The solid solution prepared by the dry method has different unit-cell parameters, and it contains a larger amount of covalently bonded tin, except at very low x values or highly positive y values, and the Sn²⁺ recoil-free fraction is much smaller. In the present work, a study of the phase transition that takes place when precipitated Ba_1−x Sn _x Cl_1+y F_1−y is heated has been undertaken. A dramatic increase of the amount of covalently bonded tin(II) occurred on heating.     

The first barium tin(II) bromide fluoride

In an effort to prepare barium tin(II) bromide fluorides for the first time, possibly similar to the chloride fluorides obtained earlier in our laboratory, precipitation reactions were carried out by mixing aqueous solutions of SnF₂ and of BaBr₂.2H₂O. In contrast with the chloride fluoride system, a single powdered phase was obtained throughout the SnF₂ – BaBr₂ system, with the yield being maximum at X ≈ 0.25, where X is the molar fraction of barium bromide in the reaction mixture. Phase identification with the JCPDS database failed to produce a match, confirming that a new phase had been produced. The exact chemical composition of the new compound has not been obtained yet. Based on the X value for the maximum yield, the Sn/Ba ratio is likely to be 3/1 or 2/1. The Mössbauer spectrum at ambient conditions shows that bonding to tin(II) is covalent, therefore with the tin lone pair being stereoactive. The Mössbauer parameters (δ = 3.68 mm/s, Δ = 0.99 mm/s) are similar to those of SnBrF and of Sn₂BrF₅, thereby showing that tin is bonded to both fluorine and bromine. The larger isomer shift and lower quadrupole splitting than in tin(II) fluorides show that the stereoactivity of the tin lone pair is lower than in the fluorides. The Mössbauer parameters fit well the linear correlation of the quadrupole splitting versus the isomer shift” that has been shown to be present in other series of tin(II) compounds. The linear decrease on this correlation shows that the contribution of non-spherical orbitals (p and d) to the lone pair is a much larger contributor to the quadrupole splitting than lattice distortions. The structure is likely made of Ba²⁺ cations and tin(II) fluoride bromide polyatomic anions, with covalent bonding withinthe anions.     

A Structural Study of Some Metal Diethyldithiocarbamate Chelates by X-ray Photoelectron Spectroscopy

The diethyldithiocarbamate chelates of copper (II), lead (II) and tin (IV) have been prepared and characterized. Pure or nearly pure metal diethyldithiocarbamate (DEDTC) chelates could be prepared through recrystallization. The x-ray photoelectron spectra (XPS) for the recrystallized samples were obtained. Three different carbons (C Is) in the diethyldithiocarbamate molecule can be recognized through a computer deconvolution system. Sulfer 2p showed two peaks of spin doublet S 2p_1/2 and S 2p_3/2. Based on the XPS results we may conclude that the diethyldithiocarbamate ligand forms an unusual 4-membered chelate ring structure with the metal ion, both sulfur having bonding with the metal. The N in the DEDTC may also bind with the metal.     

Mößbauer-Effekt im normalleitenden und supraleitenden Zustand von Sn119

The number of Moessbauer quanta from the 23.8 keV state of Sn¹¹⁹ in a tin metal source was measured after attenuation by a 16.1 mg/cm² absorber of tin metal, as a function of temperature above and below the transition point of superconductivity. Source and absorber were kept at the same temperature. The data give evidence of a discontinuous change at the transition temperature: The transmitted intensity is lowered by (1,3±0.15)·10^?3 in the superconducting state of source and absorber. This corresponds to an increase of the Debye-Waller-factor by about 0,4%.     

Using Mössbauer spectroscopy to choose the sites that can be occupied by divalent tin

Mössbauer spectroscopy can be a useful structural tool to assist crystallographic methods for site assignment when the compound under investigation contains divalent tin. The goal of this work was to show that the structure of tin(II) fluoride, also know as stannous fluoride, SnF₂, could have been solved 14 years earlier if Mössbauer spectroscopic results, already known, had been used. A first attempt to solve the crystal structure, carried out by Bergerhoff in 1962 seemed to find the tin positions, however, it failed to find the positions of fluorine. Further extensive studies by Dénès et al. in the mid 1970s yielded the same results as those of Bergerhoff, despite the use of a Nonius CAD-4 automatic diffractometer, in contrast with Bergerhoff’s film work. The tin positions yielded a residual of 0.23, and Fourier difference maps showed significant electron density that could be fluorine atoms, however, their number did not match the number of fluorine atoms expected and several F-F distances were way too short. In addition, refinement using these possible fluorine positions led to no improvement of the residual factor. Finally, the crystal structure was published by McDonald et al. in 1976. It was found that the tin sublattice determined by Bergerhoff was basically correct, except that half of the tin atoms found by Bergerhoff to be on the (4b) and (4e) special Wyckoff sites were actually on the (8f) general site. A translation of the origin of the unit-cell by the [1/8, 0, 3/16] vector allows to change the tin Wyckoff sites from (4b), (4e) and (8f) to two (8f) sites, while keeping the basic spatial distribution of tin. A method has now been designed, using ¹¹⁹Sn Mössbauer spectroscopy, to test the suitability of some Wyckoff sites for divalent tin, using the Mössbauer spectrum. The tin(II) doublet (δ = 3.430(3) mm/s, Δ = 1.532(3) mm/s) shows that the lone pair is on a hybrid orbital, therefore, it is stereoactive, and it results that tin cannot be on either the (4b) or (4e) tin site since both an inversion center and a 2-fold axis would generate a second lone pair unless the 2-fold axis were along the tin-lone pair axis.     

Vibrational spectra of crystalline potassium ferri- and ferrocyanide

The IR spectra of the crystalline salts K₃[Fe(CN)₆] (I) and K₄[Fe(CN)₆] (II) have been studied in the 1600–5000 cm^–1 range for the purpose of investigating the spectral difference in the valence states of the central atoms of the complex anions. The appearance of the doublet structure of thev ₆ band in the spectrum of salt II is due to distortion of its anion to D_4h symmetry. The vibrational spectra of both salts are interpreted.In conclusion, I should like to express ray sincere appreciation to Academician A. N. Terenin for his guidance and to L. A. Grivov and D. S, Bystrov for their valuable comments.     

双显色剂协同显色光度法测定锡

在ｐＨ ５．０ 的ＮａＡｃ－ＨＡｃ缓冲溶液中, ＰＶＡ 存在时, 锡和邻苯二酚紫（ＰＶ） 与罗丹明Ｂ（ＲｈＢ） 生成离子缔合物, 其组成为Ｓｎ∶ＰＶ∶ＲｈＢ＝ １∶２∶４。缔合物最大吸收波长为５６０ ｎｍ , 表观摩尔吸光系数ε＝１．１８×１０５ Ｌ·ｍ ｏｌ－ １ ·ｃｍ － １ 。锡量在０～１５ μｇ／２５ｍ Ｌ范围内符合比耳定律。拟定方法已用于某些样品中微量锡的测定, 结果满意。     

Berichtigung

The Fe compounds (Et₄N)₂{[((TSP) (TSPH)Fe]₂suc}³) and K[Fe(TSP) (TSPH)prop] · 3H₂O³) were characterized by means of ⁵⁷Fe Moessbauer spectroscopy and magnetic measurements. In the temperature region from 300 to 390 K the Fe(III) of both compounds undergoes a discontinuous transition from low spin state to high spin state, returning only slowly into low spin state after cooling to room temperature. This process causes a hysteresis behaviour of the magnetic values. The spin crossover is connected with a complex isomerization. Moessbauer spectra of the compounds show a significant asymmetry, which can be explained by relaxation effects according to Blume's theory.     

Far Infrared and Raman Spectra of Some Crystalline Iodomercurate Complexes

Abstract

Vibrational spectra of crystalline powders of [Nien₂] [HgI₃]₂ and [Men₂] [HgI₄] (where en = ethylene-diamine chelated to M = Ni(II), Pd(II) or Pt(II)) have been measured at room and liquid-nitrogen temperatures. The bands observed in the low frequency region 200–10 cm^?1 are interpreted in terms of mainly internal vibrations of the anions and external lattice modes. Raman and far infrared spectra are compared in order to make structural deductions. In comparison with present knowledge of the stereochemistry and vibrational spectroscopy of other iodomercurates, the triiodo-mercurate salt seems to contain nearly planar trigonal anions, while the tetraiodomercurates contain discrete tetrahedra. Probable site symmetries of the anions which may explain the spectra are discussed.     

Solid-state NMR studies of some tin(II) compounds

High-resolution NMR spectra of [Formula: see text] nuclei, particularly (119)Sn and (31)P, in solid tin(II) phosphite, SnHPO(3), and tin(II) phosphate, SnHPO(4), are presented. The results are discussed in relation to the crystal structures. Spinning sideband analysis has been carried out for both nuclei, giving information on the shielding tensors. Satellite peaks allow the indirect Sn,Sn coupling constants to be determined. Surprisingly large values of 2600+/-200Hz and 4150+/-200Hz are reported for SnHPO(3) and SnHPO(4) respectively. The satellite peaks were investigated by using a single Hahn echo for each refocusing time, which showed that the observed splittings result from (119)Sn, (117)Sn coupling. For SnHPO(3), the calculated relative intensities of the satellites for six intra-layer coupling interactions are in agreement with the experiment values, but for SnHPO(4) the coupling appears to be inter-layer in nature. Tin-119 (and in one case phosphorus-31) shielding tensor data derived from MAS NMR are also reported for four other crystalline tin(II) compounds, namely tin diphosphate, tin oxalate, tin sulphate and calcium tin ethylenediamine tetraacetate.     

Reaction of stannous fluoride in hydrogen peroxide

The reaction of SnF₂ stannous fluoride with aqueous solutions of H₂O₂ hydrogen peroxide was studied as a function of the molar ratio H₂O₂/SnF₂ in the range 0.02 to 5.00. The products were characterized by thermal analysis, X-ray diffraction and tin119 Mössbauer spectroscopy. The X-ray diffraction pattern of all samples shows only highly broadened lines, characteristic of microcrystalline SnO₂ (average particle diameter: 39 Å). Thermal analyses show that the material is hydrated. Mössbauer spectroscopy gives a broad single line at approximately 0 mm/s, characteristic of SnO₂ for all samples, and in some cases a tin(II) doublet with =3.1 mm/s and =1.9 mm/s.     

固相分光光度法测定食品中痕量锡

本文研究了以邻苯二酚紫为显色剂固相分光光度法测定痕量锡的新方法 ,在 pH =2 5条件下直接在树脂相于最大吸收波长 5 70nm处测量 ,锡含量在 0～ 15 0 μg·L- 1 范围内符合比尔定律 ,表观摩尔吸光系数可达 7 2× 10 6L·mol- 1 ·cm- 1 ,该法可应用于食品中痕量锡的测定     

Oxidation and passivating effect in tin(II) fluoride and chloride fluoride solid solutions: a <Superscript>119</Superscript>Sn Mössbauer study

Divalent tin fluorides and chloride fluorides appear to be stable relative to oxidation to tetravalent tin at ambient temperature. X-ray diffraction shows only the line of the tin(II) compound, however the ¹¹⁹Sn Mössbauer spectrum of all tin(II) polycrystalline samples has a small broad peak at ca. 0 mm/s. This is the case of polycrystalline α ?SnF₂, while the spectrum of a large single crystal polished sufficiently thin shows only the tin(II) doublet, with no SnO₂ peak at 0 mm/s. This shows that there is surface oxidation of each solid particle, to give a thin amorphous layer of SnO₂ stannic oxide. However, the Mössbauer peak of SnO₂ does not grow with prolonged exposure to air at ambient temperature, therefore it must be assumed that the layer of SnO₂ has a passivating effect, however oxidation increases at higher temperatures. We have investigated in this work the passivating effect of a layer of SnO₂ in two types of solid solutions: (i) in the fluorite type M_1?xSn_xF₂, where the amount of tin at low x values is not sufficient to provide full coverage of the surface of the particles, and (ii) in the PbClF type doubly disordered solid solution, Ba_1?xSn_xCl_1+yF_1?y. It was found that passivation works well in the M_1?xSn_xF₂ solid solution, however most of the time, it does not work so well for Ba_1?xSn_xCl_1+yF_1?y where it is strongly dependent on the method of preparation and the bonding strength, as shown by the variation versus the tin(II) recoil-free fraction.     

New Hofmann-like spin crossover compound with 3,5-lutidine

A new type III of 3,5-lutidine spin crossover coordination compound with formula Fe(3,5-lutidine)₂Ni(CN)₄·2[(H₂O)(3,5-lutidine)] 2c has been obtained. The ratio of the high spin state (HS) iron (II) changing to the low spin state (LS) iron (II) in 2c is higher than that of type I and type II 3,5-lutidine coordination polymer 2a and 2b previously reported. ⁵⁷Fe Mössbauer spectra of 2c show two different doublets which correspond to HS1 (inner doublet lines) and HS2 (outer doublet lines). The intensity of the HS1 doublet decreases on cooling to 80 K while the intensity of another component, the LS singlet, increases. The 90 % of the HS1 doublet change to the LS singlet is probably due to suitable environments of octahedral iron (II) ions coordinated by four nitrogen atoms of cyano groups and two nitrogen atoms of 3,5-lutidine ligands. We also prepared the Hofmann-like 3,5-dichloropyridine coordination compound Fe(3,5-dichloropyridine)₂Ni(CN)₄ ·2[(3,5-dichloropyridine)(H₂O)] 2d to compare it with 2c. ⁵⁷Fe Mössbauer spectra of 2d show that 2d is not a spin crossover coordination compound.     

一种用于同位素分离在线穆斯堡尔谱学的PPAC

研制了一种用于同位素分离在线穆斯堡尔谱学的平行板雪崩计数器，计数器仅重40g。用它测量由穆斯堡尔共振吸收后放出的内转换电子，采用85％^119Sn同位素增丰的SnO2作为阴极吸收材料，测得的穆斯堡尔谱的信噪比为11，是一种适合在线穆斯堡尔实验的计数器。对该计数器的性能进行了讨论。A Parallel Plate Avalanche Counter （PPAC） with weighted about 40 g was developed for isotope separator on-line Moessbauer Spectroscopy. It detects the internal conversion electrons emitted from the resonance Moessbauer nuclide. The signal-to-noise ratio of the spectra reaches 11 for 85% enriched ^119SnO2 cathode and absorber. It is an effective detector for on-line Moessbauer experiments. The perform ance of the counter was discussed in detail.     

Phase stabilization in cinnarizine complexes using X-ray profile analysis

Characterization of cobalt(II), cadmium(II), copper(II) and tin(II) cinnarizine complexes have been carried out using conductivity, electronic spectra, infrared, nmr, thermogravimetric and X-ray analyses to establish the nature of phase stabilization in these materials. Also, the intrinsic strain components present in these materials during the formation have been computed using wide-angle X-ray scattering analysis. The variation of the crystallite shape ellipsoid in these materials has been discussed on the basis of Hosemann’s paracrystalline model.     

Conversion Electron Moessbauer Spectroscopie Studies on Ion Implanted Iron Layers

Conversion electron Moessbauer spectroscopy (CEMS) is a method very suitable for the study of ion implanted iron. It is demonstrated on nitrogen and phosphorus implanted iron layers. Using this technique not the 14.4-keV-gamma-rays as in the case of the conventional Moessbauer transmission experiments but the conversion and Auger electrons are detected. These electrons have a maximum energy of 7.3 keV. The Moessbauer signal can be obtained from a surface layer of about 300 nm. But the main fraction of the signal, namely 65%, comes from the first 50 nm. This range is just interesting for ion implantation. Depending on the test conditions different iron nitrides are formed by the nitrogen implantation and the phosphorus implantation can result in both amorphization and compound formation in the implanted layer.     

The splitting of hyperfine lines of57Fe nuclei in RF magnetic field

It is shown experimentally, that for Moessbauer nuclei affected by the radio-frequency (RF) magnetic field of sufficient intensity at frequencies corresponding to NMR, splitting of Zeeman sublevels of nuclei and changes in Moessbauer spectral structure occurs. Depending on the frequency of alternating field each spectral line is splitinto (2·Ig,e +1) comporients, Ig,e-being the nuclear spin of ground and excited state, respectively. The intensity of RF components and the energy gap between them are extremely sensitive to the frequency and the intensity of the RF magnetic field.     

Low-temperature vibrational properties of tin nanoparticles in porous glass

The heat capacity has been studied in the temperature range 2.2–40 K and in magnetic fields up to 2 T in tin, which has been embedded in nanometer-size pores in glass having diameter ∼7 nm, in bulk tin and in glass with empty pores. Comparison of the properties of tin nanoparticles and bulk tin has been performed. An increase in the coefficient of electronic heat capacity has been found in nanostructured tin as compared with the bulk tin, and also a considerable deviation of the low-temperature lattice heat capacity from the Debye law in the temperature region T > 3 K has been found. The fact that the density of thermal vibrations in nanocrystalline tin for low energies is higher than in bulk tin has been established using low-temperature heat capacity data.