As one of the most widely used domestic fuels, the detection of possible leakages of Liquefied Petroleum (LP) gas from production plants, from cylinders during their storage, transport and usage is of utmost importanc...As one of the most widely used domestic fuels, the detection of possible leakages of Liquefied Petroleum (LP) gas from production plants, from cylinders during their storage, transport and usage is of utmost importance. This article discusses a study of the response of undoped and chlorine doped electrodeposited n-type Cuprous Oxide (Cu2O) films to of LP gas. Undoped n-type Cu2O films were fabricated in an electrolyte bath containing a solution of sodium acetate and cupric acetate whereas n-type chlorine doped Cu2O thin films were prepared by adding a 0.02 M cuprous chloride (CuCl2) into an electrolyte solution containing lactic acid, cupric sulfate and sodium hydroxide. The n-type conductivity of the deposited films was determined using spectral response measurements. The structural and morphological properties of the fabricated films were monitored using X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM). Due to doping, the overall conductivity of the chlorine doped n-type Cu2O films increased by several orders of magnitude. The temperature dependent gas responses of both the undoped and chlorine doped n-type Cu2O thin films to the LP gas was monitored by measuring the electrical resistance (R), and using the contact probe method at a constant gas flow rate of 0.005 ml/s. Upon exposure to gases, both doped and undoped films showed a good response to the gas by increasing/decreasing the electrical resistance by ΔR. The undoped n-type Cu2O thin films showed a negative response (ΔR 2O thin films initially showed a positive response (ΔR > 0) to the LP gas which then reversed its sign to give a negative response which peaked at 52°C. The positive response shown by the chlorine doped Cu2O films vanished completely at 42°C.展开更多
V defects in GaN layer grown on Si (111) using metalorganic chemical vapor deposition (MOCVD) were investigated by atomic force microscopy (AFM), plan-view transmission electron microscopy (TEM) and energy-dispersive ...V defects in GaN layer grown on Si (111) using metalorganic chemical vapor deposition (MOCVD) were investigated by atomic force microscopy (AFM), plan-view transmission electron microscopy (TEM) and energy-dispersive X-ray spectrometer (EDS). Dislocations are the origination of V defects. Stress field around dislocations induce the concentration of C atoms, furthermore, slow growth rate on those {10-11} planes are suggested as being responsible for the initiation of V defects. The formation mechanism of V defects was discussed.展开更多
Manganese(Mn)doped cadmium sulphide(Cd S)nanoparticles were synthesized using a chemical method.It was possible to decrease Cd S:Mn particle size by increasing Mn concentration.Investigation techniques such as ultravi...Manganese(Mn)doped cadmium sulphide(Cd S)nanoparticles were synthesized using a chemical method.It was possible to decrease Cd S:Mn particle size by increasing Mn concentration.Investigation techniques such as ultraviolet-visible(UV-Vis)absorption spectroscopy and photoluminescence(PL)spectroscopy were used to determine optical properties of Cd S:Mn nanoparticles.Size quantization effect was observed in UV-Vis absorption spectra.Quantum efficiency for luminescence or the internal magnetic field strength was increased by doping Cd S nanoparticles with Mn element.Orange emission was observed at wavelength~630 nm due to ^(4)T_1→^(6)A_1 transition.Isolated Mn~(2+)ions arranged in tetrahedral coordination are mainly responsible for luminescence.Luminescence quenching and the effect of Mn doping on hyperfine interactions in the case of Cd S nanoparticles were also discussed.The corresponding weight percentage of Mn element actually incorporated in doping process was determined by atomic absorption spectroscopy(AAS).Crystallinity was checked and the average size of nanoparticles was estimated using the X-ray diffraction(XRD)technique.Cd S:Mn nanoparticles show ferromagnetism at room temperature.Transmission electron microscopy(TEM)images show spherical clusters of various sizes and selected area electron diffraction(SAED)patterns show the polycrystalline nature of the clusters.The electronic states of diluted magnetic semiconductors(DMS)ofⅡ-Ⅵgroup Cd S nanoparticles give them great potential for applications due to quantum confinement.In this study,experimental results and discussions on these aspects have been given.展开更多
文摘As one of the most widely used domestic fuels, the detection of possible leakages of Liquefied Petroleum (LP) gas from production plants, from cylinders during their storage, transport and usage is of utmost importance. This article discusses a study of the response of undoped and chlorine doped electrodeposited n-type Cuprous Oxide (Cu2O) films to of LP gas. Undoped n-type Cu2O films were fabricated in an electrolyte bath containing a solution of sodium acetate and cupric acetate whereas n-type chlorine doped Cu2O thin films were prepared by adding a 0.02 M cuprous chloride (CuCl2) into an electrolyte solution containing lactic acid, cupric sulfate and sodium hydroxide. The n-type conductivity of the deposited films was determined using spectral response measurements. The structural and morphological properties of the fabricated films were monitored using X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM). Due to doping, the overall conductivity of the chlorine doped n-type Cu2O films increased by several orders of magnitude. The temperature dependent gas responses of both the undoped and chlorine doped n-type Cu2O thin films to the LP gas was monitored by measuring the electrical resistance (R), and using the contact probe method at a constant gas flow rate of 0.005 ml/s. Upon exposure to gases, both doped and undoped films showed a good response to the gas by increasing/decreasing the electrical resistance by ΔR. The undoped n-type Cu2O thin films showed a negative response (ΔR 2O thin films initially showed a positive response (ΔR > 0) to the LP gas which then reversed its sign to give a negative response which peaked at 52°C. The positive response shown by the chlorine doped Cu2O films vanished completely at 42°C.
基金Project supported by Program for New Century Excellent Talents in University and Nature Science Foundation of Hebei Province (E2005000042)
文摘V defects in GaN layer grown on Si (111) using metalorganic chemical vapor deposition (MOCVD) were investigated by atomic force microscopy (AFM), plan-view transmission electron microscopy (TEM) and energy-dispersive X-ray spectrometer (EDS). Dislocations are the origination of V defects. Stress field around dislocations induce the concentration of C atoms, furthermore, slow growth rate on those {10-11} planes are suggested as being responsible for the initiation of V defects. The formation mechanism of V defects was discussed.
文摘Manganese(Mn)doped cadmium sulphide(Cd S)nanoparticles were synthesized using a chemical method.It was possible to decrease Cd S:Mn particle size by increasing Mn concentration.Investigation techniques such as ultraviolet-visible(UV-Vis)absorption spectroscopy and photoluminescence(PL)spectroscopy were used to determine optical properties of Cd S:Mn nanoparticles.Size quantization effect was observed in UV-Vis absorption spectra.Quantum efficiency for luminescence or the internal magnetic field strength was increased by doping Cd S nanoparticles with Mn element.Orange emission was observed at wavelength~630 nm due to ^(4)T_1→^(6)A_1 transition.Isolated Mn~(2+)ions arranged in tetrahedral coordination are mainly responsible for luminescence.Luminescence quenching and the effect of Mn doping on hyperfine interactions in the case of Cd S nanoparticles were also discussed.The corresponding weight percentage of Mn element actually incorporated in doping process was determined by atomic absorption spectroscopy(AAS).Crystallinity was checked and the average size of nanoparticles was estimated using the X-ray diffraction(XRD)technique.Cd S:Mn nanoparticles show ferromagnetism at room temperature.Transmission electron microscopy(TEM)images show spherical clusters of various sizes and selected area electron diffraction(SAED)patterns show the polycrystalline nature of the clusters.The electronic states of diluted magnetic semiconductors(DMS)ofⅡ-Ⅵgroup Cd S nanoparticles give them great potential for applications due to quantum confinement.In this study,experimental results and discussions on these aspects have been given.
