Orientation relationship between α-Fe precipitate and α-Al2O3 matrix in iron-implanted sapphire

Fe ions were implanted into α-Al₂O₃ single crystals (sapphire) at room temperature and annealed in a reducing atmosphere. The orientation relationships (ORs) between α-Fe particles and sapphire matrix were investigated using transmission electron microscopy (TEM). All the α-Fe particles have the orientation relationship (OR) of (1 1 1)_α-Fe || (0 0 0 1)_sapphire and ${[1\overline{1}0]}_{\alpha \text{-Fe}}\left|\right|{[11\overline{2}0]}_{\text{sapphire}}$ with sapphire. This OR is predicted precisely by the coincidence of reciprocal lattice points (CRLP) method. The other OR of (1 1 0)_α-Fe || (0 0 0 1)_sapphire and ${[111]}_{\alpha \text{-Fe}}\left|\right|{[5\overline{1}\overline{4}0]}_{\text{sapphire}}$ reported before is confirmed by the same method to be one of the secondary preferred orientation relationships in the α-Fe/sapphire system.     

Examining the fragmentation of 158 A GeV lead ions on copper target: Charge-changing cross sections

A stack of plastic CR-39 Track Detectors were exposed to 158 A GeV ²⁰⁷Pb ions at the CERN-SPS beam facility. The exposure of stack was performed at normal incidence with a fluence of about $1500\mathrm{ions}/{\mathrm{cm}}^2$. The total number of lead ions in each spill was about $7.8\times {10}^4$ with eight spills on each stack. For the stack with the Cu target, the lengths of etched cones on one face of the CR-39 detectors (before and after the target) were measured. Using these measurements and charge identification methodology in CR-39 track detectors, total and partial charge changing cross sections of 158 A GeV ${\mathrm{Pb}}^{82+}$ ions on Cu and CR-39 targets are determined in the charge region $63⩽Z⩽82$. The possibilities of presence and absence of odd–even effect in measured partial charge changing cross sections of 158 A GeV Pb ions for Cu and CR-39 targets are described. The charge resolution $({\sigma }_Z)$ achieved in the present experiment is $\sim 0.18\mathrm{e}$–0.21e. The analysis of discrepancies between our experimental results and other published results for the identical reaction is also presented.     

Origin of TSL peaks located at 200–250 K in UV-irradiated PbWO4 crystals

Thermally stimulated luminescence (TSL) was studied for many ${\mathrm{PbWO}}_4$ crystals after their selective irradiation at 80–220 K in the 3.4–5.0 eV energy range to clarify the origin of the defects responsible for the TSL peaks located in the 200–250 K range. The conclusion is made that both in ${\mathrm{PbWO}}_4$ and ${\mathrm{PbWO}}_4$:$\mathrm{Mo}$ crystals the total TSL intensity and the intensity ratio of various TSL peaks are mainly determined by the concentration and type of oxygen and lead vacancies which depend on the crystal preparation and annealing conditions and on the concentration of trivalent rare-earth impurity ions. The TSL peak near 200 K is ascribed to $\{{\mathrm{Pb}}^{+}–{\mathrm{WO}}_3\}$ centers and the peak in the 210–230 K range, to the electron centers, containing oxygen vacancies of the type of ${\mathrm{WO}}_2$ and WO. Only the 250 K peak arises from electron ${\mathrm{MoO}}_4^{3-}$ centers. Thermally stimulated processes are accompanied with the green G(II) emission.     

The recombination channels of luminescence excitation in YAG:Yb single crystalline films

Absorption and emission spectra, luminescence decay kinetics and thermostimulated luminescence of X-ray irradiated YAG:Yb single crystalline films were studied. Two emission bands peaked at 420 and 488 nm have been detected in the investigated films. The strong thermal quenching of luminescence band at 488 nm was observed above 160 K. The influence of growth conditions and annealing in air on the lifetime of ${\mathrm{Yb}}^{3+}$ ion excited state in the IR spectral region have been revealed. The recombination mechanisms of the $f–f$ transition at ${\mathrm{Yb}}^{3+}$ ion excitation, as well as the mechanism of lifetime shortening for the excited ${\mathrm{Yb}}^{3+}$ luminescence have been discussed.     

Decolourization of direct blue 15 by Fenton/ultrasonic process using a zero-valent iron aggregate catalyst

Decolourization of direct azo dye, direct blue 15 (DB15), by an advanced Fenton process coupled with ultrasonic irradiation (Fenton/US) was investigated. Zero-valent iron (ZVI) aggregates were used as the catalyst. A positive synergistic effect occurred when Fenton’s reagent was combined with ultrasonic irradiation. Experimental results showed that the optimum conditions for decolourization were pH 3.0, Fe(0) 1 g/L, H₂O₂ 5.15 × 10^?3 mol/L with ultrasound density of 120 W/L at 60 kHz. These conditions yielded 99% decolouration of 4.7 × 10^?5 M DB15 (4130 ADMI) solution within 10 min. DB15 decolouration follows the first-order decolouration kinetics. Although the solutions containing H₂CO₃, Cl^?, ${\text{ClO}}_4^{-}$, ${\text{NO}}_3^{-}$ and ${\text{SO}}_4^{2-}$ ions did not have a significant effect on the decolouration, the ${\text{H}}_2{\text{PO}}_4^{-}$ ion did decrease the decolouration rate. High ultrasonic input power accelerated the reaction and increased decolourization efficiency. The cost effectiveness of this process at high ultrasound density could be controlled despite the high electricity costs incurred by the process. ZVI aggregates were reusable; however, an increase in the number of times ZVI was recycled decreased the decolourization rate. This study demonstrates that a Fenton/US process can effectively decolour the direct azo dye DB15 in wastewater.     

Negative thermal expansion property of Er0.7Sr0.3NiO3 − δ

A new kind of negative thermal expansion (NTE) material of Er_0.7Sr_0.3NiO_3 − δ is synthesized by solid-state method and investigated. It is found that Er_0.7Sr_0.3NiO_3 − δ crystallizes in orthorhombic structure with rod-shaped grains. Ceramic Er_0.7Sr_0.3NiO_3 − δ exhibits NTE coefficient of $-39.0\times {10}^{-6}{\text{K}}^{-1}$ from 655 to 780 K. The results of X-ray diffraction, temperature dependence of Raman spectroscopy and differential scanning calorimetry (DSC) suggest that the NTE phenomenon relates to its phase transition from orthorhombic to rhombohedral.     

YbNi2: A heavy fermion ferromagnet

Measurements of the magnetization and specific heat of YbNi₂ binary alloy are reported. The DC magnetic susceptibility displays a ferromagnetic behavior with a Curie temperature T_C=10.5 K, one of the highest found in Yb compounds. Moreover, the temperature dependence of the specific heat exhibits a lambda anomaly with a peak of 5.12 J/mol K at 9.4 K. The analysis also shows an additional magnetic contribution around 32 K stemming from the crystalline electric field of a quartet at ${\Delta }_1=72\mathrm{K}$ and a doublet at ${\Delta }_2=126\mathrm{K}$, according to the splitting of the Yb³⁺ ion in cubic symmetry. From the magnetic contribution to the specific heat, a relatively high Kondo temperature $T_K=27\mathrm{K}$ is estimated. Below the magnetic transition, the specific heat shows a huge value of the electronic coefficient ${\gamma }_{\mathit{LT}}=573\mathrm{mJ}/\mathrm{mol}\mathrm{K}$, which is a signature of a heavy fermion behavior. Therefore, this alloy is a fine example of enhanced ferromagnetism and heavy fermion behavior among Yb compounds.     

Aspartame tablets—gamma dose response and usability for routine radiation processing dosimetry using spectrophotometry

Aspartame tablets were studied for gamma dose response, using spectrophotometric read-out method. The optimum concentration for ferrous ions was $2\times {10}^{-4}\mathrm{mol}{\mathrm{dm}}^{-3}$ and xylenol orange with $2.5\times {10}^{-1}\mathrm{mol}{\mathrm{dm}}^{-3}$ of sulphuric acid for the optimum acidity in FX solution. Wavelength of maximum absorbance is 548 nm. Post-irradiation stability is appreciable i.e. for not less than one month. Dose response is non-linear with third order polynomial fit, in the dose range of 1000–10000 Gy. This system of aspartame was further used for carrying out relative percentage dose profile measurement in Gamma Cell-220. Results obtained were inter-compared with that of a glutamine dosimeter, which showed that maximum difference between the values of aspartame and glutamine systems is within $\pm 10\%$.     

Fast intrinsic emission in Cs2CdI4 single crystal

The spectral-luminescent studies of the ${\mathrm{Cs}}_2{\mathrm{CdI}}_4$ single crystals are reported. The fast luminescence in the 3.6–2.0 eV energy range with decay time $\tau =4.6\mathrm{ns}$ was revealed in the crystal under high-energy excitation $(E_{\mathrm{exc}}>8\mathrm{eV})$ at 9 K. This luminescence is supposed to be caused by the hole transitions between subbands of the split valence band. The energy-band picture for ${\mathrm{Cs}}_2{\mathrm{CdI}}_4$ crystals was calculated as a proof of the luminescence model.     

Ultrasound-assisted preparation of alkaline graphite intercalation compounds

Alkaline graphite intercalation compounds were prepared by flake graphite, potassium dichromate, concentrated sulfur acid and sodium hydroxide under ultrasound irradiation and characterized by scanning electron microscopy and X-ray diffraction. The influences of solution alkalinity, bath temperature and reaction time on the expansion volume were also investigated. The results show that alkaline graphite intercalation compounds were prepared when ${\text{SO}}_4^{2-}$ and OH^? ions were inserted into the spaces between the graphene planes, producing a flake morphology and multilevel structure. At the same time that the interlayer volume expanded, the oxidizing ability of the solid increased. When the bath temperature, the reaction time and the solution alkalinity were at 33–36 °C, at 60 min and for pH = 13, the top expansion volume was 35 mL g^?1.