Study on Elimination of Oxygen Absorption in Chalcogenide Glass

Decreasing the absorption is a key process for chalcogenide glass preparation. The glass character of oxygen absorption and some means to remove the oxygen absorption were introduced.

Oxygen Relief/Absorption and Superconductivity of Bi-Pb-Sr-Ca-Cu-O Compounds

The oxygen relief/absorption,superconduc— tivity and structure of(Bi_(1-x)Pb_x)_2Sr_2Ca_2— Cu_3O_y compounds have been studied by TGA, electrical resistance measurement and X-ray diffraction.The amount of oxygen which can be re- leased and superconductivity of the compounds are correlative to Pb content.The release of oxygen in- creases when x less than 0.2 and decreases when x exceeds 0.2 with increasing x.The appropriate con- tent of Pb for superconductivity is in the range of 0.1<x<0.3,which corresponds to the relative large amount of oxygen that can be released.It is found according to electric resistance measurement that quenching is favourable to form the‘85K’phase and slow cooling the‘110K’phase.The experimen- tal results suggest that a relation exists between the superconductivity and the oxygen content in Bi sys- tem containing Pb.As the T_c of‘85K’phase de- creases and that of‘110K’phase increases with in- creasing oxygen content,it is possible that the effect of oxygen content in‘85K’phase and‘110K’ phase on the superconductivity is different.

Significant photoelectrical response of epitaxial graphene grown on Si-terminated 6H-SiC

Photoelectrical response characteristics of epitaxial graphene （EG） films on Si- and C-terminated 6H-SiC, and transferred chemical vapor deposition （CVD） graphene films on Si-terminated 6H-SiC have been investigated. The results show that upon illumination by a xenon lamp, the photocurrent of EG grown on Si-terminated SiC significantly increases by 147.6%, while the photocurrents of EG grown on C-terminated SiC, and transferred CVD graphene on Si-terminated SiC slightly decrease by 0.5% and 2.7%, respectively. The interfacial buffer layer between EG and Si-terminated 6H-SiC is responsible for the significant photoelectrical response of EG. Its strong photoelectrical response makes it promising for optoelectronic applications.

Magnetic behaviors of cerium oxide-based thin films deposited using electrochemical method

Zn and Co multi-doped CeO2 thin films have been prepared using an anodic electrochemical method. The structures and magnetic behaviors are characterized by several techniques, in which the oxygen states in the lattice and the absorptive oxygen bonds at the surface are carefully examined. The absorptive oxygen bond is about 50% of the total oxygen bond by using a semi-quantitative method. The value of actual stoichiometry δ′ is close to 2. The experimental results indicate that the thin films are of a cerium oxide-based solid solution with few oxygen vacancies in the lattice and many absorptive oxygen bonds at the surface. Week ferromagnetic behaviors were evidenced by observed M-H hysteresis loops at room temperature. Furthermore, an evidence of relative ferromagnetic contributions was revealed by the temperature dependence of magnetization. It is believed that the ferromagnetic contributions exhibited in the M-H loops originate from the absorptive oxygen on the surface rather than the oxygen vacancies in the lattice.

Absorption behavior of lattice oxygen in Ce_(0.8)Y_(0.2)O_(2-δ) at intermediate temperature

The absorption behavior of lattice oxygen for Ce0.8Y0.2O2-δ(YDC) crystal was investigated. Combined with TG-DSC, XRD, Raman and XPS characterization, lattice oxygen absorption occurs at intermediate temperature(from 500 to 800 ℃),which is related to the oxygen vacancies consumption,and no phase change is observed in this process. In electric conductivity relaxation(ECR) experiment, prolonged oxygen diffusion process is observed above 600 ℃, which may be caused by oxygen absorption process. And through ECR experiments,the bulk diffusion coefficient Dchemand surface exchange coefficient Kexfor YDC dense sample are measured as 6,5×10-5-2×10-4cm2/s and Kex=2×10-4-9×10-4cm/s at intermediate temperature range.

Oxygen transfer characteristics of water and bubble mixture pipe flow through two sudden contractions and expansions

The dissolved oxygen （DO） concentration is an important index of water quality. This paper studies the dissolved oxygen recovery of the water and bubble mixture pipe flow through two sudden contractions and expansions. A 3-D computational fluid dy- namics model is established to simulate the water and bubble mixture flow with a DO transport model. An experiment is conducted to validate the mathematical model. The mathematical model is used to evaluate the effect of geometric parameters on the head loss coefficient, the relative saturation coefficient and the oxygen absorption efficiency. It is found that the contraction ratio is a signi- ficant influencing factor, other than the relative length and the relative distance. Given the same relative length and relative distance, the head loss coefficient, the relative saturation coefficient and the oxygen absorption efficiency increase with the decrease of the contraction ratio, respectively. Given the same relative length and contraction ratio, the head loss coefficient increases with the in- crease of the relative distance firstly, and then decreases gradually, in contrast, the relative saturation coefficient and the oxygen ab- sorption efficiency decrease with the increase of the relative distance firstly, and then increase gradually, the relative saturation coefficient and the oxygen absorption efficiency are inversely proportional to the head loss coefficient, respectively.

Amorphous nickel-iron oxides/carbon nanohybrids for an efficient and durable oxygen evolution reaction

Highly efficient and durable water oxidation electrocatalysts are critically important in a wide range of clean energy technologies,including water electrolyzers and rechargeable metal-air batteries.Here,we report a novel sonochemical approach to synthesize amorphous nickel-iron oxides/carbon nanohybrids with tunable compositions for the oxygen evolution reaction （OER）.The sonochemically synthesized amorphous electrocatalysts with optimal composition exhibit a low overpotential of 290 mV at 10 mA＆#183;cm-2 and a Tafel slope of 31 mV＆#183;decade-1 in a 0.1 M KOH electrolyte,outperforming the benchmark RuO2 catalyst.Meanwhile,these nanohybrids are also highly stable and remain amorphous even after prolonged cycling.In addition to amorphism,sonochemistry endows as-prepared nickel-iron oxides/carbon nanohybrids with a simultaneously formed carbon scaffold and internal Ni（0）,which can enhance the stability and activity for the OER.This work demonstrates that sonochemistry is a unique method for synthesizing amorphous metal oxides toward an efficient and durable OER.

On the solutions of an oxygen absorption model

In this note we present the Adomian decomposition method for solving a simple model for the diffusion and absorption of oxygen in tissue. The method is examined for computational efficiency and accuracy.

Regulating nitrogen vacancies within graphitic carbon nitride to boost photocatalytic hydrogen peroxide production

Introducing nitrogen vacancies is an effective method to improve the catalytic performance of g-C_(3)N_(4)-based photocatalysts,whereas understanding how nitrogen vacancies types affect the catalytic performance remains unclear.Herein,two different types of nitrogen vacancies were successfully introduced into g-C_(3)N_(4)by pyrolysis of melamine under argon and ammonia atmosphere with subsequent HNO3 oxidation.The pyrolysis atmosphere is found to have a significant influence on the introduced nitrogen vacancies type,where tertiary nitrogen groups(N_(3)C)and sp2-hybridized nitrogen atoms(N_(2)C)were the preferred sites for the formation of nitrogen vacancies under ammonia and argon pyrolysis,respectively.Moreover,nitrogen vacancies from N3C are experimentally and theoretically demonstrated to facilitate the narrowed band gap and the improved oxygen absorption capability.As expected,the optimal catalyst exhibits high H_(2)O_(2)yield of 451.8µM,which is 3.8 times higher than the pristine g-C_(3)N_(4)(119.0µM)after 4 h and good stability after10 photocatalytic runs.