In an effort to improve the performance of superconductors in the field and high temperatures it is important to study the superconducting mechanism. For this reason, the cation substitution can be conducted. One of t...In an effort to improve the performance of superconductors in the field and high temperatures it is important to study the superconducting mechanism. For this reason, the cation substitution can be conducted. One of the high Tc superconductors Gd1Ba2Cu3O7−δ phase with Sr substitution has been synthesized, i.e. Gd1(Ba2−xSrx)Cu3O7−δ compound. The sample was synthesized by using a solid-state reaction method with a wet mixing, sintered for 12 hours at temperature 900°C. The synthesis results are characterized by using XRD. The results of Match-3 software analysis showed high (higher 85%) Gd1Ba2Cu3O7−δ phase was formed. The Sr substitution causes changes to the structure, i.e. the lattice parameters a, b and c, where the orthorhombicity tends to decrease with increasing Sr content. Refinement results show that based on the oxygen occupancy, the total oxygen content tends to increase.展开更多
SINCE the discovery of high-T<sub>c</sub> superconductors, experiments have revealed that the phase diagrams of La<sub>2-x</sub>Sr<sub>x</sub>CuO<sub>4</sub> and YBa<...SINCE the discovery of high-T<sub>c</sub> superconductors, experiments have revealed that the phase diagrams of La<sub>2-x</sub>Sr<sub>x</sub>CuO<sub>4</sub> and YBa<sub>2</sub>Cu<sub>3</sub>O<sub>6+x</sub> resemble each other. The antiferromagnetic phase is commonly situated in the vicinity of the superconductive phase. In Bi-2212 sys-展开更多
A micro fluidized bed reactor was used to study the self-sustaining catalytic combustion of carbon monoxide(CO).The Cu_(1−x)Ce_(x)O_(y) catalyst,as well as the pure CuO and CeO_(2),are used to investigate the contribu...A micro fluidized bed reactor was used to study the self-sustaining catalytic combustion of carbon monoxide(CO).The Cu_(1−x)Ce_(x)O_(y) catalyst,as well as the pure CuO and CeO_(2),are used to investigate the contributing mechanism of different active sites including dispersed CuO and Cu–Ce solid solutions.The ignition temperature(Ti)of CO over these catalysts at a flow rate of 2000 mL/min followed the order:74℃(Cu_(0.5)Ce_(0.5)O_(y))<75℃(Cu_(0.25)Ce_(0.75)O_(y))<84℃(Cu_(0.75)Ce_(0.25)O_(y))<105℃(CuO)<500℃(CeO_(2)).Furthermore,the lean combustion limits(equivalence ratioϕ)over these catalysts under the flow rates of 750–3000 mL/min(through fixed,bubbling,and fluidized bed)were also measured,which are Cu_(0.5)Ce_(0.5)O_(y)<Cu_(0.25)Ce_(0.75)Oy<Cu_(0.75)Ce_(0.25)O_(y)<CuO<CeO_(2).The fluidized bed was simulated using the Eulerian two-fluid model(TFM)coupled with a diffusion/kinetic-limited reaction model to evaluate the influence of operation conditions on the self-sustained combustion of CO.The predicted maximum temperature agreed with the experimental measurements,demonstrating the validity of the kinetic model and simulation parameters.The results of catalytic combustion with increasing CO concentrations suggest that the catalytic combustion reaction could co-exist with the flamed combustion.When a high concentration of CO is used,a blue-purple flame caused by CO combustion appears in the upper part of the fluidized bed,indicating that the range of CO-containing exhaust gas purification could be expanded to a larger range using the fluidized-bed catalytic combustion technique.展开更多
Nanosized Ba_(1-x)Bi_(x)Fe_(1-x)Cu_(x)O_(3)(12–50 nm)with x values of 0,0.01,0.05,and 0.1 system was prepared using the Pechini method.Structural,morphological,surface and optical characterizations were performed for...Nanosized Ba_(1-x)Bi_(x)Fe_(1-x)Cu_(x)O_(3)(12–50 nm)with x values of 0,0.01,0.05,and 0.1 system was prepared using the Pechini method.Structural,morphological,surface and optical characterizations were performed for the prepared samples.Cubic phase was the predominant phase for the undoped BaFeO_(3)and Bi and Cu co-doped BaFeO_(3)samples.Minor phases of monoclinic Ba_(2)Fe_(2)O_(5),orthorhombic BaFe_(2)O_(4)and orthorhombic BaCO_(3)were identified for all the prepared samples.Ba_(0.95)Bi_(0.05)Fe_(0.95)Cu_(0.05)O_(3)sample has the lowest band gap(2.43 e V).98.1%paracetamol removal was achieved with 0.75 g/L of Ba_(0.95)Bi_(0.05)Fe_(0.95)Cu_(0.05)O_(3)at pH9 after 120 min.The paracetamol degradation follows the pseudo first-order kinetics.HO·is the main oxidative species responsible for the paracetamol degradation.Gas chromatography–mass spectrometry(GC–MS)analysis was performed at the end of the photocatalytic degradation experiment under optimum operating condition using Ba_(0.95)Bi_(0.05)Fe_(0.95)Cu_(0.05)O_(3)to explain the reaction mechanism and identify the intermediate by-products which is confirmed by ultraviolet/visible(UV/Vis)spectroscopy study at different reaction times.展开更多
基金This report is part of the fundamental research report with contract No.486 127/UN14.2/PNL.01.03.00/2016.
文摘In an effort to improve the performance of superconductors in the field and high temperatures it is important to study the superconducting mechanism. For this reason, the cation substitution can be conducted. One of the high Tc superconductors Gd1Ba2Cu3O7−δ phase with Sr substitution has been synthesized, i.e. Gd1(Ba2−xSrx)Cu3O7−δ compound. The sample was synthesized by using a solid-state reaction method with a wet mixing, sintered for 12 hours at temperature 900°C. The synthesis results are characterized by using XRD. The results of Match-3 software analysis showed high (higher 85%) Gd1Ba2Cu3O7−δ phase was formed. The Sr substitution causes changes to the structure, i.e. the lattice parameters a, b and c, where the orthorhombicity tends to decrease with increasing Sr content. Refinement results show that based on the oxygen occupancy, the total oxygen content tends to increase.
文摘SINCE the discovery of high-T<sub>c</sub> superconductors, experiments have revealed that the phase diagrams of La<sub>2-x</sub>Sr<sub>x</sub>CuO<sub>4</sub> and YBa<sub>2</sub>Cu<sub>3</sub>O<sub>6+x</sub> resemble each other. The antiferromagnetic phase is commonly situated in the vicinity of the superconductive phase. In Bi-2212 sys-
基金support from the National Natural Science Foundation of China(No.52176141).
文摘A micro fluidized bed reactor was used to study the self-sustaining catalytic combustion of carbon monoxide(CO).The Cu_(1−x)Ce_(x)O_(y) catalyst,as well as the pure CuO and CeO_(2),are used to investigate the contributing mechanism of different active sites including dispersed CuO and Cu–Ce solid solutions.The ignition temperature(Ti)of CO over these catalysts at a flow rate of 2000 mL/min followed the order:74℃(Cu_(0.5)Ce_(0.5)O_(y))<75℃(Cu_(0.25)Ce_(0.75)O_(y))<84℃(Cu_(0.75)Ce_(0.25)O_(y))<105℃(CuO)<500℃(CeO_(2)).Furthermore,the lean combustion limits(equivalence ratioϕ)over these catalysts under the flow rates of 750–3000 mL/min(through fixed,bubbling,and fluidized bed)were also measured,which are Cu_(0.5)Ce_(0.5)O_(y)<Cu_(0.25)Ce_(0.75)Oy<Cu_(0.75)Ce_(0.25)O_(y)<CuO<CeO_(2).The fluidized bed was simulated using the Eulerian two-fluid model(TFM)coupled with a diffusion/kinetic-limited reaction model to evaluate the influence of operation conditions on the self-sustained combustion of CO.The predicted maximum temperature agreed with the experimental measurements,demonstrating the validity of the kinetic model and simulation parameters.The results of catalytic combustion with increasing CO concentrations suggest that the catalytic combustion reaction could co-exist with the flamed combustion.When a high concentration of CO is used,a blue-purple flame caused by CO combustion appears in the upper part of the fluidized bed,indicating that the range of CO-containing exhaust gas purification could be expanded to a larger range using the fluidized-bed catalytic combustion technique.
文摘Nanosized Ba_(1-x)Bi_(x)Fe_(1-x)Cu_(x)O_(3)(12–50 nm)with x values of 0,0.01,0.05,and 0.1 system was prepared using the Pechini method.Structural,morphological,surface and optical characterizations were performed for the prepared samples.Cubic phase was the predominant phase for the undoped BaFeO_(3)and Bi and Cu co-doped BaFeO_(3)samples.Minor phases of monoclinic Ba_(2)Fe_(2)O_(5),orthorhombic BaFe_(2)O_(4)and orthorhombic BaCO_(3)were identified for all the prepared samples.Ba_(0.95)Bi_(0.05)Fe_(0.95)Cu_(0.05)O_(3)sample has the lowest band gap(2.43 e V).98.1%paracetamol removal was achieved with 0.75 g/L of Ba_(0.95)Bi_(0.05)Fe_(0.95)Cu_(0.05)O_(3)at pH9 after 120 min.The paracetamol degradation follows the pseudo first-order kinetics.HO·is the main oxidative species responsible for the paracetamol degradation.Gas chromatography–mass spectrometry(GC–MS)analysis was performed at the end of the photocatalytic degradation experiment under optimum operating condition using Ba_(0.95)Bi_(0.05)Fe_(0.95)Cu_(0.05)O_(3)to explain the reaction mechanism and identify the intermediate by-products which is confirmed by ultraviolet/visible(UV/Vis)spectroscopy study at different reaction times.
