Ⅰ. INTRODUCTION As nanosolid is compacted from ultrafine particles, a large volume fraction of the material is constituted by grain boundaries or interfaces. Because of the small size and boundary effects, the proper...Ⅰ. INTRODUCTION As nanosolid is compacted from ultrafine particles, a large volume fraction of the material is constituted by grain boundaries or interfaces. Because of the small size and boundary effects, the properties of nanosolids are superior to those of the traditional materials with the same compositions. The gas sensing properties of"nano SnO<sub>2</sub> solids are high sensitivity and rapid respgnding speed, which increase with the decrease of crystal grain size.展开更多
The present study confers to the fabrication and its characterization of magnesium alloy(AZ91E)based nano composites with nano Al_(2)O_(3) particulate reinforcements.A novel Semi Solid stir casting technique was adopt...The present study confers to the fabrication and its characterization of magnesium alloy(AZ91E)based nano composites with nano Al_(2)O_(3) particulate reinforcements.A novel Semi Solid stir casting technique was adopted for the fabrication of the composite.An average particle size of 50 nm was used as reinforcement to disperse in matrix.The effects of change in weight fraction of reinforcements on the distribution of particles,particle–matrix interfacial reactions,physical as well as mechanical properties were reported.The SEM and EDS analysis has shown the uniform distribution of particles in the composite along with the presence of elements.The mechanical properties of reinforced and unreinforced composite were evaluated and presented.Fractography of tensile specimens was also discussed.展开更多
Sn_(1−x)Er_(x)O_(2)(x=0%,8%,16%,24%)micro/nanofibers were prepared by electrospinning combined with heat treatment using erbium nitrate,stannous chloride and polyvinylpyrrolidone(PVP)as raw materials.The target produc...Sn_(1−x)Er_(x)O_(2)(x=0%,8%,16%,24%)micro/nanofibers were prepared by electrospinning combined with heat treatment using erbium nitrate,stannous chloride and polyvinylpyrrolidone(PVP)as raw materials.The target products were characterized by thermogravimetric analyzer,X-ray diffrotometer,fourier transform infrared spectrometer,scanning electron microscope,spectrophotometer and infrared emissivity tester,and the effects of Er^(3+)doping on its infrared and laser emissivity were studied.At the same time,the Sn_(1−x)Er_(x)O_(2)(x=0%,16%)doping models were constructed based on the first principles of density functional theory,and the related optoelectronic properties such as their energy band structure,density of states,reflectivity and dielectric constant were analyzed,and further explained the mechanism of Er^(3+)doping on SnO_(2)infrared emissivity and laser absorption from the point of electronic structure.The results showed that after calcination at 600℃,single rutile type SnO_(2)was formed,and the crystal structure was not changed by doping Er^(3+).The calcined products showed good fiber morphology,and the average fiber diameter was 402 nm.The infrared emissivity and resistivity of the samples both decreased first and then increased with the increase of Er^(3+)doping amount.When x=16%,the infrared emis-sivity of the sample was at least 0.71;and Er^(3+)doping can effectively reduce the reflectivity of SnO_(2)at 1.06μm and 1.55μm,when x=16%,its reflectivity at 1.06μm and 1.55μm are 50.5%and 40%,respectively,when x=24%,the reflectivity at 1.06μm and 1.55μm wavelengths are 47.3%and 42.1%,respectively.At the same time,the change of carrier concentration and electron transition before and after Er^(3+)doping were described by first-principle calculation,and the regulation mechanism of infrared emissivity and laser reflectivity was explained.This study provides a certain experimental and theoretical basis for the development of a single-type,light-weight and easily prepared infrared and laser compatible-stealth material.展开更多
基金Project supported by the Laboratory of Internal Friction and Defects in Solids, Academia Sinica
文摘Ⅰ. INTRODUCTION As nanosolid is compacted from ultrafine particles, a large volume fraction of the material is constituted by grain boundaries or interfaces. Because of the small size and boundary effects, the properties of nanosolids are superior to those of the traditional materials with the same compositions. The gas sensing properties of"nano SnO<sub>2</sub> solids are high sensitivity and rapid respgnding speed, which increase with the decrease of crystal grain size.
文摘The present study confers to the fabrication and its characterization of magnesium alloy(AZ91E)based nano composites with nano Al_(2)O_(3) particulate reinforcements.A novel Semi Solid stir casting technique was adopted for the fabrication of the composite.An average particle size of 50 nm was used as reinforcement to disperse in matrix.The effects of change in weight fraction of reinforcements on the distribution of particles,particle–matrix interfacial reactions,physical as well as mechanical properties were reported.The SEM and EDS analysis has shown the uniform distribution of particles in the composite along with the presence of elements.The mechanical properties of reinforced and unreinforced composite were evaluated and presented.Fractography of tensile specimens was also discussed.
基金supported by the Key Research and Development Program of Hebei Province(No.21351501D)A Provincial and Ministerial Scientific Research Project(LJ20212C031165)Basic Frontier Science and Technology Innovation Project of Army Engineering University of PLA(KYSZJQZL2210)。
文摘Sn_(1−x)Er_(x)O_(2)(x=0%,8%,16%,24%)micro/nanofibers were prepared by electrospinning combined with heat treatment using erbium nitrate,stannous chloride and polyvinylpyrrolidone(PVP)as raw materials.The target products were characterized by thermogravimetric analyzer,X-ray diffrotometer,fourier transform infrared spectrometer,scanning electron microscope,spectrophotometer and infrared emissivity tester,and the effects of Er^(3+)doping on its infrared and laser emissivity were studied.At the same time,the Sn_(1−x)Er_(x)O_(2)(x=0%,16%)doping models were constructed based on the first principles of density functional theory,and the related optoelectronic properties such as their energy band structure,density of states,reflectivity and dielectric constant were analyzed,and further explained the mechanism of Er^(3+)doping on SnO_(2)infrared emissivity and laser absorption from the point of electronic structure.The results showed that after calcination at 600℃,single rutile type SnO_(2)was formed,and the crystal structure was not changed by doping Er^(3+).The calcined products showed good fiber morphology,and the average fiber diameter was 402 nm.The infrared emissivity and resistivity of the samples both decreased first and then increased with the increase of Er^(3+)doping amount.When x=16%,the infrared emis-sivity of the sample was at least 0.71;and Er^(3+)doping can effectively reduce the reflectivity of SnO_(2)at 1.06μm and 1.55μm,when x=16%,its reflectivity at 1.06μm and 1.55μm are 50.5%and 40%,respectively,when x=24%,the reflectivity at 1.06μm and 1.55μm wavelengths are 47.3%and 42.1%,respectively.At the same time,the change of carrier concentration and electron transition before and after Er^(3+)doping were described by first-principle calculation,and the regulation mechanism of infrared emissivity and laser reflectivity was explained.This study provides a certain experimental and theoretical basis for the development of a single-type,light-weight and easily prepared infrared and laser compatible-stealth material.
