Behavior of Microamounts of <Superscript>22</Superscript>Na, <Superscript>85</Superscript>Sr, <Superscript>137</Superscript>Cs,and <Superscript>152</Superscript>Eu in Sorption and Coprecipitation on Mixed Potassium Neodymium Ferrocyanide from Solutions

Sorption of ⁸⁵Sr, ¹³⁷Cs, ²²Na, and ¹⁵²Eu on solid mixed potassium neodymium ferrocyanide KNd[Fe(CN)₆]·4H₂O from neutral, acidic, and alkaline media and also coprecipitation of these radionuclides with KNd[Fe(CN)₆]·4H₂O in its formation from a homogeneous solution were studied. It was found that ⁸⁵Sr and ²²Na do not noticeably coprecipitate with solid KNd[Fe(CN)₆]·4H₂O and are not sorbed by this substance. In aqueous medium, depending on the cesium concentration in solution, from 80 to 98% of ¹³⁷Cs coprecipitates with solid KNd[Fe(CN)₆]·4H₂O. In this case, the distribution coefficient K_d depends on both the cesium concentration in solution and solution pH. Within 30 min of contact of the solid and liquid phases, the degree of recovery of ¹³⁷Cs from aqueous solution with KNd[Fe(CN)₆]·4H₂O is approximately 95.0% of the initial amount. ¹⁵²Eu coprecipitates with solid KNd[Fe(CN)₆]·4H₂O during its formation from a homogeneous solution to 98–99.9%. The degree of recovery of ¹⁵²Eu from aqueous solution with KNd[Fe(CN)₆]·4H₂O precipitate within 60 min of contact of the solid and liquid phases is 70.3% of the initial amount.     

Luminescence of Cu<Superscript>+ </Superscript>in halosulphate phosphor

Ultraviolet photo-excited luminescence from Cu-doped halosulphate phosphors has been investigated. The intense emission of the spectrum is assigned to electronic transitions 3d⁹4s¹ → 3d¹⁰ in Cu⁺ ions. Increase in photoluminescence (PL) peak intensity suggesting that Cu plays an important role in PL emission in the present matrix. However, limited hosts with Cu⁺ as luminescence center were studied due to difficulties in incorporating it in a luminescence form. Cu-doped halosulphate phosphors were synthesized by wet chemical method. X-ray diffraction and PL characterization of phosphors has been reported in this article. The article discusses the luminescence of Cu⁺ and the simple method of incorporation in various new hosts.     

Improvement of the Magnetization of Barium Hexaferrites Induced by Substitution of Nd<Superscript>3+</Superscript> Ions for Fe<Superscript>3+</Superscript> Ions

Barium hexagonal ferrites (BaNd _x Fe_12?x O ₁₉) have been synthesized by initial high-energy milling of the precursors and calcining subsequently. The as-prepared samples are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and vibrating sample magnetometry (VSM). XRD and SEM examinations reveal that a high-crystallized hexagonal BaNd _x Fe_12?x O ₁₉ with lamellar morphology is obtained when the precursor is calcined at 1200^°C in air for 3 h. The hexagonal crystalline structure of BaFe₁₂ O ₁₉ is not changed after doping Nd³⁺ ions in BaFe₁₂ O ₁₉. However, lattice parameters a and b values increase with an increase in Nd content at first, then decrease. Nd substitution may improve the magnetic properties of BaNd _x Fe_12?x O ₁₉. BaNd_0.1Fe_11.9 O ₁₉, obtained at 1050^°C, has the highest specific saturation magnetization value (80.81 emu/g) and magnetic moment (16.21 μ _B); BaNd_0.2Fe_11.8 O ₁₉, obtained at 950^°C, has the highest coercivity value, 4075.19 Oe.     

Surface hardening in N<Superscript>+</Superscript> implanted polycarbonate

The influence of low energy nitrogen ions on the surface hardness of polycarbonate has been studied by implanting some of these specimens with 100 keV N⁺ ions at a beam current of 1 μA/cm² in the dose range of 1 × 10¹⁵ to 1 × 10¹⁷ ions cm^?2. Knoop microhardness has been found to be increased nearly 24 times at a load of 9.8 mN, for the dose of 1 × 10¹⁷ ions cm^?2. The structural changes occurred in implanted specimens were studied by Raman analysis, UV–Visible spectroscopy, and X-ray diffraction techniques. Raman studies point toward the formation of a structure resembling hydrogenated amorphous carbon. Disordering in the surface structure (I _D/I _G ratio) has also been found to increase with ion fluence using Raman technique. UV–Visible spectroscopic analysis shows a clear enhancement in Urbach energy (disorder parameter) from a value of 0.61 eV (virgin sample) to 1.72 eV (at a fluence of 1 × 10¹⁷ N⁺ cm^?2) with increasing ion dose. The increase in Urbach energy has been found to be correlated linearly with the increase in Knoop microhardness number. Results of X-ray diffraction analysis also indicate disordering in implanted layers as a result of implantation. In the present work, the possible mechanism behind the formation of harder surfaces due to implantation has been discussed in detail.     

Laser-induced anisotropy in Ag<Superscript>+</Superscript>-doped glasses

An induced optical anisotropy is observed as a result of interaction of a high-power CW Ar⁺ laser beam, with silver-ion-exchanged glasses. We have shown that the absorption of the beam by the thin layer of Ag⁺ produces a temperature gradient resulting in a radial stress on the surface of the sample. The induced anisotropy makes the sample behave as a thin uniaxial optical medium with axis along the direction of the beam propagation. For the polarized light, the induced anisotropy restricts the application of micro-lenses, which are made by this method. The average refraction index of the interaction area is measured.     

Li<Superscript>+</Superscript> ion conductivities in boro-tellurite glasses

Lithium ion conductivity has been investigated in a boro-tellurite glass system, LiCl.LiBO₂.TeO₂. In the absence of LiCl, the conductivity increases with increasing non-bridging oxygen (NBO) concentration. LiCl addition has little influence on total conductivity although the observed barriers are low. Formation of LiCl clusters appears evident. In the a.c. conductivity and dielectric studies, it is observed that the conductivity mechanism remains the same in all compositions and at all temperatures. A suggestion is made that Li⁺ ion transport may be driven by bridging oxygen ↔r non-bridging oxygen (BO ↔r NBO) switching, which is why the two different types of Li⁺ ions in the clusters and in the neighbourhood of NBOs, do not manifest in the conductivity studies.     

Sorption of <Superscript>90</Superscript>Sr and <Superscript>90</Superscript>Y with stable and metastable modifications of calcium carbonate

A comparative study of sorption of ⁹⁰Sr²⁺ and ⁹⁰Y³⁺ cations from aqueous solutions saturated with respect to calcium carbonate on the metastable CaCO₃ modifications (aragonite and vaterite) and also on the stable CaCO₃ modification (calcite) was carried out at 20°C. The sorption of these radionuclides from the solutions containing Sr(NO₃)₂ carrier and without it was studied. Aragonite shows the highest sorption capacity for ⁹⁰Sr²⁺, and these parameters are the lowest for calcite. All the CaCO₃ metastable modifications irreversibly sorb ⁹⁰Sr²⁺ and ⁹⁰Y³⁺ cations and therefore show promise for sorptive decontamination of water from ⁹⁰Sr.     

Depth profile XPS analysis of polymeric materials by C<Subscript>60</Subscript><Superscript>+</Superscript> ion sputtering

When the depth profile of chemical composition is studied with X-ray photoelectron spectroscopy (XPS), the Ar⁺ ion sputtering method is generally adopted. However, in the case of polymers, chemical composition is destroyed, and so it is impossible to obtain accurate depth profile on polymers. In this research, the depth profile XPS analysis of aliphatic polymers, aromatic polymers, fluorine containing polymers, and natural polymers were conducted with the sputtering source being C₆₀ ⁺ ion, and the degree of damage was examined while comparing the results with the case of conventional Ar⁺ ion. It was found that Ar⁺ ion induces significant carbonization in all the polymers above-mentioned. Meanwhile, it turned out that C₆₀ ⁺ ion causes little damage to most polymers. However, in the case of the non-aromatic polymers containing halogen, hydroxyl, carboxyl, and ether groups in their backbones, the following three damage modes were found: (1) the functional group ratio changes by over ±10%; (2) new functional groups are formed; (3) the above (1) and (2) phenomena occur simultaneously.     

Sorption of Uranyl Ions on Aluminosilicate Gels

Sorption of uranyl ions from 0.09 M aqueous KCl on aluminosilicate gels washed to remove intermicellar liquid was studied. The aluminosilicate gels are efficient sorbents with respect to uranyl ions, and their sorption power increases with decreasing acidity. Although uranyl cations form strong carbonate complexes, carbonate anions do not affect noticeably the uranyl sorption. Owing to strong sorption of uranyl ions on aluminosilicate gels, these materials can be used for building artificial geochemical barriers to prevent uranium penetration into underground water.     

Recombination luminescence of CaI<Subscript>2</Subscript> crystals activated with Eu<Superscript>2+</Superscript>, Gd<Superscript>2+</Superscript>, Tl<Superscript>+</Superscript>, Pb<Superscript>2+</Superscript>, and Mn<Superscript>2+</Superscript>

The spectral characteristics of thermostimulated luminescence, steady-state roentgenoluminescence and photostimulated luminescence (PSL) buildup and decay kinetics, and the effect of IR irradiation on the roentgenoluminescence yield and glow curves of CaI₂:Eu²⁺, CaI₂:Gd²⁺, CaI₂:Tl⁺, CaI₂:Pb²⁺, CaI₂:Mn²⁺, and CaI₂: Pb²⁺, Mn²⁺ crystals grown by the Bridgman-Stockbarger method have been studied in the temperature range 90–295 K. Coupled with earlier data, the present results on the influence of oxygen and hydrogen impurities on the spectral characteristics of CaI₂ indicate that the activation of calcium iodide with Eu²⁺, Gd²⁺, Tl⁺, Pb²⁺, and Mn²⁺ leads to the formation of cation impurity-native defect complexes, which act as carrier traps and are responsible for the thermostimulated luminescence in the range 150–295 K. IR exposure after 90-K x-ray excitation gives rise to flash PSL and influences the thermostimulated luminescence light sum. The nature of the emission and trapping centers involved and the mechanisms of recombination luminescence excitation in the crystals are discussed.     

Isolation of <Superscript>58</Superscript>Co, <Superscript>54</Superscript>Mn,and <Superscript>86</Superscript>Rb from <Superscript>89</Superscript>Sr production wastes

Procedures for isolation of ⁵⁸Co, ⁵⁴Mn, and ⁸⁶Rb from ⁸⁹Sr production wastes are described. The production of ⁸⁹Sr was based on irradiation of natural Y in the form of oxide, placed in 1Cr18Ni10Ti stainless steel ampules, on a BR-10 fast reactor. ⁵⁸Co and ⁵⁴Mn were isolated from the casings of stainless steel ampules, and ⁸⁶Rb, from the tail solution after the isolation of ⁸⁹Sr.     

Recovery of <Superscript>131</Superscript>I and <Superscript>137</Superscript>Cs from a solution simulating NPP trap waters

Sorption of ¹³¹I and ¹³⁷Cs from a solution simulating NPP trap waters on various inorganic and organic sorbents was studied. The highest degree of ¹³¹I recovery (>99%) can be attained with Fizkhimin granulated sorbents based on coarsely porous silica gel containing Ag and Ni in 1: 4 ratio, with K _d for ¹³¹I exceeding 10⁵ ml g⁻¹ at V/m = 10³ ml g⁻¹ and contract time of the solid and liquid phases of 120 min. Elevation of the solution temperature to 40°C does not affect the degree of ¹³¹I and ¹³⁷Cs recovery. The degree of ¹³⁷Cs recovery in all the experiments did not exceed 35%. The degree of ¹³¹I recovery by coprecipitation with AgCl and Ag₄[Fe(CN)₆] was about ∼96% and only 65%, respectively.     

Mixing in Au/Ge system induced by Ar<Superscript>+</Superscript> ion irradiation

Rutherford Backscattering Spectrometry (RBS) and Electrical Resistivity Measurements (ERM) were used to investigate the mixing of Au/Ge bilayer deposited onto glass substrate induced by Ar ions. Mixing was initiated by bombarding the sample with 400 keV ⁴⁰Ar⁺ beam with a fluence up to 1.2 × 10¹⁷ ions/cm² at a constant flux of 0.25 μA/cm². To assist the evaluation of the experimental results, all spectra were simulated using “RUMP” computer code. RBS results indicated that ion beam mixing led to a formation of AuGe₂ compound. The mixed region was noticed to increase with the gradual increase of Ar⁺ fluence. Results were also compared with current theoretical models used to describe the mixing process. The Bφrgesen thermal spike model was found to accurately predict the diffusion in Au/Ge interface. An increase in the electrical resistivity of the film was detected during Ar⁺ irradiation.     

Distribution of N<Superscript>+</Superscript> centers in synthetic diamond single crystals

The distribution of N⁺ centers in synthetic diamond grown by the temperature-gradient method in a nickel-containing metal-carbon system has been studied using FTIR mapping. The results clearly demonstrate that the distribution has a complex nature and is directly related to the sectorial structure of the crystal and linear growth rate, whose effects are analyzed with consideration for literature data. The aggregation rate of N⁺ single nitrogen is slower than that of neutral substitutional nitrogen (C centers).     

Structure and luminescent properties of Cs<Subscript>2</Subscript>Sr(VO<Subscript>3</Subscript>)<Subscript>4</Subscript>:Mn<Superscript>2+</Superscript>

We have developed a procedure for thermally stimulated synthesis of a cesium strontium metavanadate, Cs₂Sr(VO₃)₄:Mn²⁺ (0.01, 0.50, 1.00, 5.00 at % Mn²⁺), using MnO-containing starting mixtures. The EPR spectrum of the material containing 0.01 at % Mn²⁺ shows a hyperfine structure due to the incorporation of a small amount of manganese into the diamagnetic double metavanadate host. The luminescent and optical properties of Cs₂Sr(VO₃)₄:Mn²⁺ depend on manganese content. In contrast to higher doping levels, doping with 0.01 at % Mn²⁺ increases the integrated emission intensity of the vanadate by 10% and improves its chromaticity characteristics (approaching them to those of white light). We assume that this is due to the reduction in the density of vacancy-type growth defects, such as oxygen vacancies.     

Blistering in alloy Ti-6Al-4V from H<Superscript>+</Superscript> ion implantation

The effect of H⁺ ion implantation on surface morphology of the titanium alloy, Ti-6Al-4V, was studied, following H⁺ ion implantation of 150 keV and 250 keV energy to fluence of 2·6 × 10¹⁸ cm⁻² and 2·5 × 10¹⁹ cm⁻², respectively at ambient temperature. No detectable change was observed in surface features of either of the above specimen immediately after the implantation. However, vein like features (VLF) were observed to appear on the surface of the sample, implanted at 150 keV to a fluence of 2·6 × 10¹⁸ cm⁻², following natural ageing at room temperature for 150 days. Subsequent annealing of the above naturally aged sample, at 423 K for 150 min under vacuum (10⁻³ torr), led to development of a macroblister.     

Structural studies of geopolymers by <Superscript>29</Superscript>Si and <Superscript>27</Superscript>Al MAS-NMR

A systematic study of geopolymers by ²⁹Si and ²⁷Al MAS NMR has been carried out in an attempt to understand polymer structural details. ²⁷Al MAS NMR data shows that transient aluminium species are formed during the reaction of metakaolin with NaOH. Interaction of silicate anions with the aluminium sites of metakaolin was evident during the synthesis of geopolymers as observed from low field shift of ²⁹Si MAS NMR resonance lines of silicate centres. As the reaction progresses, the coordination of aluminium (IV, V and VI) in metakaolin changes almost completely to IV. ²⁹Si MAS NMR of selected compositions of the ternary system of sodium silicate, metakaolin and aqueous alkali reveals that geopolymerisation occurs in a distinct compositional region. At high alkalinity [> 30% (mol/mol) overall Na²O content], connectivity of silicate anions is reduced, consistent with poor polymerisation. At low alkalinity [<10% (mol/mol) overall Na²O content], a clear ²⁹Si NMR resonance line due to unconverted metakaolin is observed. NMR spectra were recorded from a series of samples with a fixed Na²O content (20 mol%) and varied SiO²/Al²O³ ratio to observe aluminium substitution in the cross-linked silicon tetrahedra of polymer network. Aluminium insertion into the silicate network is confirmed from the observed ²⁹Si NMR shift as a function of Si/Al ratio. The identification of the presence or absence of metakaolin in the cured geopolymer product is not possible even by ²⁹Si NMR as the signal from metakaolin is indistinguishable from a broad ²⁹Si NMR peak consisting of many resonance lines from the network of cross-linked silicon/aluminium tetrahedra. In an attempt to identify metakaolin signal, we prepared geopolymers with higher SiO²/Al²O³ molar ratios. Since aluminium substitutions in the silicate tetrahedral network are decreased, this results in better-resolved ²⁹Si NMR lines. The ²⁹Si NMR signal due to metakaolin is then distinguishable in the spectra of cured products in a series of samples with 3 to 11 mol% metakaolin. These results indicate that a geopolymer structure is a network of silicon/aluminium tetrahedra with some presence of unreacted metakaolin. The silicon/aluminium tetrahedra might have connectivity ranging from 1 to 4.     

Sorption of <Superscript>237</Superscript>Np(V), <Superscript>238</Superscript>U(VI), and <Superscript>137</Superscript>Cs on clays: Role of surface films of Fe(III) compounds

Mineralogical and sorption properties of sandy-argillaceous rocks proposed as a material of protecting barriers in near-surface repositories of nuclear wastes were studied. Different sorption behavior with respect to Np(V), U(VI), and ¹³⁷Cs is caused by formation of iron-containing films on the particle surface of coarse (>0.25 mm) and fine (<0.01 mm) rock fractions. The presence of Fe in the compositions of different minerals contained in the rock (chlorite, illite, montmorillonite, and hematite) was determined by scanning electron microscopy with X-ray probe microanalysis (SEM-XPMA), transmitting electron microscopy with electron energy loss spectroscopy (TEM-EELS), and Mössbauer spectroscopy. Hematite is present in the form of both separate particles and films on quartz grains. The Fe fraction in these formations was estimated.     

Sorption treatment of radioactively contaminated natural waters to remove <Superscript>90</Superscript>Sr and <Superscript>137</Superscript>Cs using bauxites and products of their processing

Sorption treatment of radioactively contaminated natural waters to remove ⁹⁰Sr and ¹³⁷Cs using an alumina production waste, red bauxite slimes, is considered. In radiostrontium sorption, they surpass both the initial bauxite ore (Boksitogorsk deposit) and adjoin rocks (limestone, dolomite, bentonite clay), and owing to porous structure they act as efficient filtering material.