Ternary teiiurite glasses with composition of xWO3（40-x）Ag2O-60TeO2（x=0-40 mol%） have been prepared by melt-quenching method.Elastic and optical properties of the glass system were obtained by ultrasonic velocity ...Ternary teiiurite glasses with composition of xWO3（40-x）Ag2O-60TeO2（x=0-40 mol%） have been prepared by melt-quenching method.Elastic and optical properties of the glass system were obtained by ultrasonic velocity measurements and UV-vis spectroscopy,respectively,while structural investigation was carried out by using Raman spectroscopy.The longitudinal and shear velocities,vLand vsshowed large increase at x from 0 to 20 mol%before decrease with further addition of WO3.Independent longitudinal modulus CLand shear modulus μ bulk modulus KeYoung’s modulus Vand Debye temperature θDshowed similar behaviors to both velocities.The large increase of the elastic moduli at x from 0 to 20 mol%is suggested to be due to the increase in WO6octahedral unit structure indicating the increase of bridging oxygen（BO） and formation of stronger Te-O-W bonds compared to Te-O-Te bonds.On the other hand,forx> 20 mol%,the decrease in the elastic moduli was due to the increase of non-bridging oxygen（NBO） as a result of formation of WO4tetrahedral via breaking Te-O-W network.Further analysis by using bulk compression and ring deformation models showed a slight decrease in the ratio of ideal bulk modulus Kbcto the experimental bulk modulus Keand average atomic ring size,/ for×< 20 mol%followed by a large increase for x > 20 mol%.Our analysis also indicates that limited ring deformation took place and the main compression mechanism in this glass system was mainly ideal isotropic compression.On the other hand,optical band gap Eoptshowed small variation for x=0-20 mol%but decreased upon higher WO3content while refractive index n showed the opposite trend.This optical behavior is suggested to be related to the changes in cross link density and NBO concentration in the glass system.展开更多
Fluorene is a polycyclic aromatic hydrocarbon, which is a hazardous toxic chemical in the environment. The measurement of low concentrations of fluorene is a subject of intense interest in chemistry and in the environ...Fluorene is a polycyclic aromatic hydrocarbon, which is a hazardous toxic chemical in the environment. The measurement of low concentrations of fluorene is a subject of intense interest in chemistry and in the environment. Polypyrrole chitosan cobalt ferrite nanoparticles are prepared using the electrochemical method. The prepared layers are characterized using field emission scanning electron microscopy, Fourier transform infrared spectroscopy, and energy dispersive spectroscopy. The layers are used to detect fluorene using the surface plasmon resonance technique at room temperature. The composite layer is evaluated after detection of fluorene using atomic force microscopy. The fluorene is bound on the layer, and the shift of the resonance angle is about 0.0052°, corresponding to the limitation of 0.01 ppm.展开更多
基金Financial support from Ministry of Education of Malaysia in the form of RACE under grant No. 600 e RMI/RACE/16/6/2 (1/ 2013) is gratefully acknowledged
文摘Ternary teiiurite glasses with composition of xWO3（40-x）Ag2O-60TeO2（x=0-40 mol%） have been prepared by melt-quenching method.Elastic and optical properties of the glass system were obtained by ultrasonic velocity measurements and UV-vis spectroscopy,respectively,while structural investigation was carried out by using Raman spectroscopy.The longitudinal and shear velocities,vLand vsshowed large increase at x from 0 to 20 mol%before decrease with further addition of WO3.Independent longitudinal modulus CLand shear modulus μ bulk modulus KeYoung’s modulus Vand Debye temperature θDshowed similar behaviors to both velocities.The large increase of the elastic moduli at x from 0 to 20 mol%is suggested to be due to the increase in WO6octahedral unit structure indicating the increase of bridging oxygen（BO） and formation of stronger Te-O-W bonds compared to Te-O-Te bonds.On the other hand,forx> 20 mol%,the decrease in the elastic moduli was due to the increase of non-bridging oxygen（NBO） as a result of formation of WO4tetrahedral via breaking Te-O-W network.Further analysis by using bulk compression and ring deformation models showed a slight decrease in the ratio of ideal bulk modulus Kbcto the experimental bulk modulus Keand average atomic ring size,/ for×< 20 mol%followed by a large increase for x > 20 mol%.Our analysis also indicates that limited ring deformation took place and the main compression mechanism in this glass system was mainly ideal isotropic compression.On the other hand,optical band gap Eoptshowed small variation for x=0-20 mol%but decreased upon higher WO3content while refractive index n showed the opposite trend.This optical behavior is suggested to be related to the changes in cross link density and NBO concentration in the glass system.
文摘Fluorene is a polycyclic aromatic hydrocarbon, which is a hazardous toxic chemical in the environment. The measurement of low concentrations of fluorene is a subject of intense interest in chemistry and in the environment. Polypyrrole chitosan cobalt ferrite nanoparticles are prepared using the electrochemical method. The prepared layers are characterized using field emission scanning electron microscopy, Fourier transform infrared spectroscopy, and energy dispersive spectroscopy. The layers are used to detect fluorene using the surface plasmon resonance technique at room temperature. The composite layer is evaluated after detection of fluorene using atomic force microscopy. The fluorene is bound on the layer, and the shift of the resonance angle is about 0.0052°, corresponding to the limitation of 0.01 ppm.
