Growth of infinite-layer (Sr,Nd)CuO2 films by MBE

Single phase, c-axis oriented infinite layer (IL) Sr_1?xNd_xCuO₂ thin films were epitaxially grown on (1 1 0) DyScO₃ substrates by molecular beam epitaxy (MBE). Electron impact emission spectroscopy (EIES) is the tool of choice for a stringent stoichiometry control which is essential for Sr_1?xNd_xCuO₂ thin film preparation. As-grown films contain excess oxygen and therefore a reduction process is necessary to induce superconductivity. In the present study special attention was paid to the underdoped region since the optimization of the reduction process becomes more difficult for lower doping levels x. Sr_0.95Nd_0.05CuO₂ films (underdoped) became superconducting with $T_c^{\text{onset}}$ = 30 K and $T_c^{\text{zero}}$ = 11.4 K after an annealing procedure.     

The high-resolution FTIR spectrum of the ν4 + ν8 band of trans-d2-ethylene (trans-C2H2D2)

The FTIR absorption spectrum of the hybrid A–B type ν₄ + ν₈ combination band of trans-C₂H₂D₂ centered at 1845.98737 cm^?1 in the 1730–1940 cm^?1 region was recorded at an unapodized resolution of 0.0063 cm^?1. A total of 2725 a- and b-type transitions was assigned and fitted to upper state (ν₄ + ν₈ = 1) rovibrational constants up to sextic terms using Watson’s A-reduced Hamiltonian in I^r representation. The b-type feature of the band was analyzed for the first time. The root-mean-square deviation of the IR fit was 0.00059 cm^?1. The most accurate set of ground state rovibrational constants up to sextic terms was also derived from the simultaneous fit of 3340 ground state combination differences from the present analysis and the ν₄ band of trans-C₂H₂D₂. The transition dipole moment ratio $\left|\frac{{\mu }_a}{{\mu }_b}\right|$ was found to be 1.95 ± 0.06.     

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.