Synthesis of AlN by NH4Cl-assisted direct nitridation of secondary Al resources was studied. Aluminum alloy scrap contained Mg and Zn element was used. Milled Al scrap （-1 mm） was mixed with NH4Cl and heated at 1000...Synthesis of AlN by NH4Cl-assisted direct nitridation of secondary Al resources was studied. Aluminum alloy scrap contained Mg and Zn element was used. Milled Al scrap （-1 mm） was mixed with NH4Cl and heated at 1000℃ for 1 h in presence of 1 L/min N2 flow gas. The nitrided product was evaluated by X-ray diffraction semi-quantitative analysis and scanning electron microscopy （SEM）. Aluminium nitride of 90.5% concentration was obtained with a hexagonal crystalline form. AlN is mostly formed in nano-whisker morphology （50～150 nm） which is homogenously distributed.展开更多
This paper reports that the lead zirconate titanate （PZT） piezoelectric composites incorporating zinc oxide nanowhiskers （ZnOw） were prepared by the conventional solid state processing. The whisker-dispersed PZT c...This paper reports that the lead zirconate titanate （PZT） piezoelectric composites incorporating zinc oxide nanowhiskers （ZnOw） were prepared by the conventional solid state processing. The whisker-dispersed PZT composites （PZT/ZnOw） presented a significant enhancement in the mechanical properties such as Young＇s modulus, tensile strength and compressive strength. Especially, the compressive strength increased from 153 MPa for the PZT to 228 MPa for the PZT/ZnOw composites. The reinforcement mechanism in strength of the composites was discussed. The me- chanical quality factors of the PZT/ZnOw composites increased considerably, while the piezoelectric constants and electromechanical coupling coefficient decreased slightly. The composites with good electrical and excellent mechanical properties are promising for further applications.展开更多
With recent developments in nanoscience and nanotechnology, carbon-based nanomaterials, such as carbon nanotubes or Fullerene nanowhiskers (FNWs), are attracting a great deal of interest. However, nanomaterials have n...With recent developments in nanoscience and nanotechnology, carbon-based nanomaterials, such as carbon nanotubes or Fullerene nanowhiskers (FNWs), are attracting a great deal of interest. However, nanomaterials have novel properties that may cause safety problems in biological systems. Although the toxic effects of multiwall carbon nanotubes (MWCNTs) in vitro and in vivo have been well described, the effect of FNWs on cells remains unclear. In the present study, we analyzed the gene expression and cytotoxicity of FNWs-treated cells. The results of cell viabil-ity and gene expression analysis indicate that FNWs has a relatively smaller ability to induce cellular gene expression as compared with MWCNTs or titania nanoparticles. Our results suggest that FNWs have weak cytotoxic effects as compared to the effects of MWCNTs and tita-nia nanoparticles.展开更多
Inspired by the transport behavior of water and ions through the aligned channels in trees,we demonstrate a facile,scalable approach for constructing biomorphic cellular Si_(3)N_(4) ceramic frameworks with well-aligne...Inspired by the transport behavior of water and ions through the aligned channels in trees,we demonstrate a facile,scalable approach for constructing biomorphic cellular Si_(3)N_(4) ceramic frameworks with well-aligned nanowhisker arrays on the surface of directionally aligned microchannel alignments.Through a facile Y(NO_(3))_(3) solution infiltration into wood-derived carbon preforms and subsequent heat treatment,we can faultlessly duplicate the anisotropic wood architectures into free-standing bulk porous Si_(3)N_(4) ceramics.Firstly,α-Si3N4 microchannels were synthesized on the surface of CB-templates via carbothermal reduction nitridation(CRN).And then,homogeneous distributed Y–Si–O–N liquid phase on the walls of microchannel facilitated the anisotropicβ-Si3N4 grain growth to form nanowhisker arrays.The dense aligned microchannels with low-tortuosity enable excellent load carrying capacity and thermal conduction through the entire materials.As a result,the porous Si_(3)N_(4) ceramics exhibited an outstanding thermal conductivity(TC,k_(R)≈6.26 W·m^(−1)·K^(−1)),a superior flexural strength(σ_(L)≈29.4 MPa),and a relative high anisotropic ratio of TC(k_(R)/k_(L)=4.1).The orientation dependence of the microstructure–property relations may offer a promising perspective for the fabrication of multifunctional ceramics.展开更多
Structural control and element doping are two popular strategies to produce semiconductors with surface enhanced Raman spectroscopy(SERS)properties.For TiO2 based SERS substrates,maintaining a good crystallinity is cr...Structural control and element doping are two popular strategies to produce semiconductors with surface enhanced Raman spectroscopy(SERS)properties.For TiO2 based SERS substrates,maintaining a good crystallinity is critical to achieve excellent Raman scattering.At elevated temperatures(N600°C),the phase transition from anatase to rutile TiO2 could result in a poor SERS performance.In this work,we report the successful synthesis of TiO2 nanowhiskers with excellent SERS properties.The enhancement factor,an index of SERS performance,is 4.96×106 for methylene blue molecule detecting,with a detection sensitivity around 10-7 mol·L-1.Characterizations,such as XRD,Raman,TEM,UV–vis and Zeta potential measurement,have been performed to decrypt structural and chemical characteristics of the newly synthesized TiO2 nanowhiskers.The photo absorption onset of MB adsorbed TiO2 nanowhiskers was similar to that of bare TiO2 nanowhiskers.In addition,no new band was observed from the UV–vis of MB modified TiO2 nanowhiskers.Both results suggest that the high enhancement factor cannot be explained by the charge-transfer mechanism.With the support of ab initio density functional theory calculations,we reveal that interfacial potassium is critical to maintain thermal stability of the anatase phase up to 900°C.In addition,the deposition of potassium results in a negatively charged TiO2 nanowhisker surface,which favors specific adsorption of methylene blue molecules and significantly improves SERS performance via the electrostatic adsorption effect.展开更多
文摘Synthesis of AlN by NH4Cl-assisted direct nitridation of secondary Al resources was studied. Aluminum alloy scrap contained Mg and Zn element was used. Milled Al scrap （-1 mm） was mixed with NH4Cl and heated at 1000℃ for 1 h in presence of 1 L/min N2 flow gas. The nitrided product was evaluated by X-ray diffraction semi-quantitative analysis and scanning electron microscopy （SEM）. Aluminium nitride of 90.5% concentration was obtained with a hexagonal crystalline form. AlN is mostly formed in nano-whisker morphology （50～150 nm） which is homogenously distributed.
基金Project supported by the National Natural Science Foundation of China (Grant Nos 50572010, 50742007 and 10672020)the National Defense Foundation of China (Grant No 401050301)the Scientific Project of 863 of China (Grant No 2007AA03Z103)
文摘This paper reports that the lead zirconate titanate （PZT） piezoelectric composites incorporating zinc oxide nanowhiskers （ZnOw） were prepared by the conventional solid state processing. The whisker-dispersed PZT composites （PZT/ZnOw） presented a significant enhancement in the mechanical properties such as Young＇s modulus, tensile strength and compressive strength. Especially, the compressive strength increased from 153 MPa for the PZT to 228 MPa for the PZT/ZnOw composites. The reinforcement mechanism in strength of the composites was discussed. The me- chanical quality factors of the PZT/ZnOw composites increased considerably, while the piezoelectric constants and electromechanical coupling coefficient decreased slightly. The composites with good electrical and excellent mechanical properties are promising for further applications.
文摘With recent developments in nanoscience and nanotechnology, carbon-based nanomaterials, such as carbon nanotubes or Fullerene nanowhiskers (FNWs), are attracting a great deal of interest. However, nanomaterials have novel properties that may cause safety problems in biological systems. Although the toxic effects of multiwall carbon nanotubes (MWCNTs) in vitro and in vivo have been well described, the effect of FNWs on cells remains unclear. In the present study, we analyzed the gene expression and cytotoxicity of FNWs-treated cells. The results of cell viabil-ity and gene expression analysis indicate that FNWs has a relatively smaller ability to induce cellular gene expression as compared with MWCNTs or titania nanoparticles. Our results suggest that FNWs have weak cytotoxic effects as compared to the effects of MWCNTs and tita-nia nanoparticles.
文摘Inspired by the transport behavior of water and ions through the aligned channels in trees,we demonstrate a facile,scalable approach for constructing biomorphic cellular Si_(3)N_(4) ceramic frameworks with well-aligned nanowhisker arrays on the surface of directionally aligned microchannel alignments.Through a facile Y(NO_(3))_(3) solution infiltration into wood-derived carbon preforms and subsequent heat treatment,we can faultlessly duplicate the anisotropic wood architectures into free-standing bulk porous Si_(3)N_(4) ceramics.Firstly,α-Si3N4 microchannels were synthesized on the surface of CB-templates via carbothermal reduction nitridation(CRN).And then,homogeneous distributed Y–Si–O–N liquid phase on the walls of microchannel facilitated the anisotropicβ-Si3N4 grain growth to form nanowhisker arrays.The dense aligned microchannels with low-tortuosity enable excellent load carrying capacity and thermal conduction through the entire materials.As a result,the porous Si_(3)N_(4) ceramics exhibited an outstanding thermal conductivity(TC,k_(R)≈6.26 W·m^(−1)·K^(−1)),a superior flexural strength(σ_(L)≈29.4 MPa),and a relative high anisotropic ratio of TC(k_(R)/k_(L)=4.1).The orientation dependence of the microstructure–property relations may offer a promising perspective for the fabrication of multifunctional ceramics.
基金supported by National Natural Science Foundation of China(21878143,21476106,and 21838004)Joint Research Fund for Overseas Chinese Scholars and Scholars in Hong Kong and Macao Young Scholars(21729601)+3 种基金the fund of State Key Laboratory of MaterialsOriented Chemical Engineering(ZK201702,KL16-01)the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)the U.S.National Science Foundation(NSF)for support through Grant No.CHE-1710102the High-Performance Computing Center of Nanjing Tech University for supporting the computational resources。
文摘Structural control and element doping are two popular strategies to produce semiconductors with surface enhanced Raman spectroscopy(SERS)properties.For TiO2 based SERS substrates,maintaining a good crystallinity is critical to achieve excellent Raman scattering.At elevated temperatures(N600°C),the phase transition from anatase to rutile TiO2 could result in a poor SERS performance.In this work,we report the successful synthesis of TiO2 nanowhiskers with excellent SERS properties.The enhancement factor,an index of SERS performance,is 4.96×106 for methylene blue molecule detecting,with a detection sensitivity around 10-7 mol·L-1.Characterizations,such as XRD,Raman,TEM,UV–vis and Zeta potential measurement,have been performed to decrypt structural and chemical characteristics of the newly synthesized TiO2 nanowhiskers.The photo absorption onset of MB adsorbed TiO2 nanowhiskers was similar to that of bare TiO2 nanowhiskers.In addition,no new band was observed from the UV–vis of MB modified TiO2 nanowhiskers.Both results suggest that the high enhancement factor cannot be explained by the charge-transfer mechanism.With the support of ab initio density functional theory calculations,we reveal that interfacial potassium is critical to maintain thermal stability of the anatase phase up to 900°C.In addition,the deposition of potassium results in a negatively charged TiO2 nanowhisker surface,which favors specific adsorption of methylene blue molecules and significantly improves SERS performance via the electrostatic adsorption effect.
