Xianting SUN
,
Lianzeng YAO
,
Chimei MO
,
Gang SHI
,
Weili CAI
,
Yimin ZHANG
,
Lide ZHANG
材料科学技术（英文）
Alumina aerogels with high porosity of nanometer size were prepared from Al, n-butanol and ethyl acetoacetate by the sol-gel route and the Na supercritical extraction drying technique. Optical experiment results showed that for alumina aerogels after annealing at 500 degrees C for 4 h one intense blue emission band appeared in the wavelength range of 400 to 800 nm, and the optical absorption edge moved from 8.0 eV of coarse grain Al2O3 to 3 similar to 5 eV and with increasing the annealing temperature, this luminescence band presented blue shifts. The reasons of these new optical properties are discussed in detail.
关键词:
Qing LIN
,
Lianzeng YAO
,
Guowei JIANG
,
Chuangui JIN
,
Weifeng LIU
,
Weili CAI
,
Zhen YAO
材料科学技术（英文）
Aligned silicon dioxide nanotubes with diameter of 60~70 nm were synthesized inside the nanoholes of an anodic Al membrane (AAM) template by pressure impregnating the AAM pores with the SiO¬2 sol. The SiO¬2 nanotubes with different wall thickness were produced by repeating the process. Using the second-order template of porous AAM with silicon dioxide nanotubes, it was fabricated the nanostructure of Fe nanowires encapsulated by SiO¬2 nanotubes by electrochemical deposition. Scanning electron microscope (SEM) and transmission electron microscope (TEM) observations show that the nanotubes and nanocables are compact, continuous and uniform. Selected area electron diffraction (SAED) pattern shows the Fe nanowire is a single crystal. The magnetic properties of these samples were checked by a vibrating sample magnetometer (VSM). The coercivities of the samples are greatly improved compared to the corresponding bulk materials.
关键词:
Template
,
null
,
null
,
null
Ye ZHANG
,
Lide ZHANG
,
Chimei MO
,
Yuanhong LI
,
Lianzeng YAO
,
Weili CAI
材料科学技术（英文）
The synthesis of dispersions of MMA (methylmethacrylate) with different concentrations of oleic acid coated nano-TiO2 particles was performed by hydrolysis of TiCl4 in the mixture solutions of MMA, oleic acid and H2O with various concentrations. When MMA :oleic acid : H2O : TiCl4 1.00 : 0.064 : 0.01 : 0.032 (by mol fraction), the dispersion of MMA with oleic acid coated nano-TiO2 particles was very stable. Optical absorption result showed that the absorption band was located in the ultraviolet range from 200 to 400 nm. This dispersion was added to a kind of automobile surface lustering agent (type II), and then this lustering agent with nano-TiO2 was coated on the surface of automobile surface paint. When the doping amount of the dispersion in the lustering agent=10 vol. pet, the state of paint (color and glossiness) did not present any change after irradiation of an ultraviolet lamp with the power of 1000 watt for two days. The sample with surface paint and lustering agent doped by 10 percent dispersion after suffering from irradiation of the sunlight for half a year (from May to November) kept the original state. However, for the samples with automobile paint and lustering agent without doping of nano-TiO2, the color and glossiness lost easily after irradiation of an ultraviolet lamp. These results prove that nano-TiO2 is a kind of high-efficient additive of paint for protection against ultraviolet irradiation.
关键词:
Mingzai WU
,
Lianzeng YAO
,
Weili CAI
,
Guowei JIANG
,
Xiaoguang LI
,
Zhen YAO
材料科学技术（英文）
Ordered ZnO nanowire arrays embedded in anodic aluminum oxide (AAO) membranes were fabricated by electrochemical deposition of Zn(NO3)2+H3BO3 solution in a boiling bath. Scanning electron microscope (SEM) and transmission electron microscope (TEM) observation results show that the polycrystalline ZnO nanowires with diameters around 100 nm were uniformly assembled into the ordered nanochannels of the AAO. The results of the investigation into photoluminescence (PL) and electronic paramagnetic resonance (EPR) measurements reveal that the interfaces between the ZnO nanowires and the pore walls of the AAO create a lot of oxygen vacancies, which are responsible for the green light emission (peaking around 512 nm) and the huge enhancement of the PL emission.
关键词:
Nanowires
,
null
,
null
Applied Physics a-Materials Science & Processing
Amorphous aluminate YAlO3 (YAO) thin films on n-type silicon wafers as gate dielectric layers of metal - oxide semiconductor devices are prepared by pulsed laser deposition. As a comparison, amorphous aluminate LaAlO3 (LAO) thin films are also prepared. The structural and electrical characterization shows that the as-prepared YAO films remain amorphous until 900 degrees C and the dielectric constant is similar to 14. The measured leakage current of less than 10(-3) A/cm(2) at a bias of V-G = 1.0 V for similar to 40-nm-thick YAO and LAO films obeys the Fowler Nordheim tunneling mechanism. It is revealed that the electrical property can be significantly affected by the oxygen pressure during deposition and post rapid thermal annealing, which may change the fixed negative charge density at the gate interface.
关键词:
hafnium oxide;si;stability;silicon;transition;dioxide;devices;hfo2
