La0.5Y0.5Ni4.8Mn0.1Al0.1和La0.5Y0.5Ni4.8Al0.2合金的储氢性能研究

针对两种新型稀土型储氢合金La0.5Y0.5Ni4.8Mn0.1Al0.1和La0.5Y0.5Ni4.8Al0.2的储氢特性进行研究分析。实验表明,相同温度下,La0.5Y0.5Ni4.8Mn0.1Al0.1和La0.5Y0.5Ni4.8Al0.2合金的PCT曲线基本重合,且都具有优良的吸氢动力学性能;相比之下,后者的滞后系数要小于前者,吸氢量较大,吸氢速率也较快,故其储氢性能较优。300次吸放氢循环实验结果表明,La0.5Y0.5Ni4.8Al0.2合金的吸氢动力学性能虽然略有下降,但抗粉化性能较好。     

Thermal Stability of Amorphous Hydride Mg_(50)Ni_(50)H_(54) and Mg_(30)Ni_(70)H_(45)

The thermal stability of amorphous ternary hydrides Mg_(50)Ni_(50)H_(54) and Mg_(30)Ni_(70)H_(45) and their corre-sponding amorphous binary alloys Mg_(50)Ni_(50) and Mg_(30)Ni_(70) were studied with X-ray diffraction(XRD) and differential scanning calorimetry(DSC). Samples of the amorphous alloys were preparedby mechanical alloying and the amorphous hydrides were obtained by charging the alloys with gas-eous hydrogen at 3.0 MPa and 423 K. It was found that the amorphous hydrides released most oftheir hydrogen before the crystallization of the essentially hydrogen depleted amorphous alloy. Thecrystallization temperature of amorphous Mg_(50)Ni_(50)H_(54) elevated and that of amorphousMg_(30)Ni_(70)H_(45) did not change in relation to the original binary amorphous alloy. This is very excep-tional for amorphous hydrides. The reason for the effects of hydrogen absorption/desorption on thecrystallization of amorphous alloys was discussed.     

Acousto-optic interaction in alpha-BaB(2)O(4)and Li(2)B(4)O(7) crystals

Experimental studies and analysis of acousto-optic diffraction in alpha-BaB(2)O(4) and Li(2)B(4)O(7) crystals are given. Ultrasonic wave velocity, elastic compliance and stiffness coefficients, and piezo-optic and photoelastic coefficients of alpha-BaB(2)O(4) and Li(2)B(4)O(7) crystals are determined. The acousto-optic figure of merit has been estimated for different possible geometries of acousto-optic interaction. It is shown that the acousto-optic figures of merit for alpha-BaB(2)O(4) crystals reach the value M(2)=(270 +/- 70) x 10(-15) s(3)/kg for the case of interaction with the slowest ultrasonic wave. The directions of propagation and polarization of those acoustic waves are obtained on the basis of construction of acoustic slowness surfaces. The acousto-optic diffraction is experimentally studied for alpha-BaB(2)O(4) and Li(2)B(4)O(7) crystals.     

Zr65Al7.5Ni10Cu15Co2.5合金的玻璃转变温度

根据Ｚｒ６５Ａｌ７。５Ｎｉ１０Ｃｕ１５Ｃｏ２。５合金的纳米晶，晶体，液体和玻璃比热的测量结果，研究了合金的玻璃转变温度与全金的热力学函数，动力学参数以及加热速度的关系。结果表明，非晶态合金玻璃转变所需转变激活能很小，玻璃转变温度实际上是由于加热速度引起的不同状态的玻璃与液体的热力学平衡温度。     

Natural Passivity of Amorphous Fe_(40)Ni_(40)P_(14)B_6 and Fe_(54.6)Ni_(38)Si_(4.1)B_(2.3)V_1 Alloys

The natural passive films forrned on Fe_(40)Ni_(40)P_(14)B_6 and Fe_(54.6)Ni_(38)Si_(4.1)B_(2.3)V_1 amorphous alloys long-term exposed in air have been studied by X-ray photoelectron spectroscopy (XPS) and Auger electron (including Ar+ ion depth profiling) spectroscopy (AES). The following aspects have been investigated: (1) chemical states of the elements in the films. binding energies and the chemical shifts measured by XPSf (2) structure and composition of the films fand (3) thickness of the passive films determined by AES depth profiling and XPS analysis.     

Nanomechanical characterization of one-step combustion-synthesized Al(4)B(2)O(9) and Al(18)B(4)O(33) nanowires

Two kinds of aluminum borate nanowires, Al(4)B(2)O(9) and Al(18)B(4)O(33), were successfully synthesized by a one-step combustion method through control of the Al:B atomic ratio and synthesis temperature. Both nanowires are single crystalline but have distinguishing growth habits. Nanoindentation tests were performed directly on individual nanowires to reveal their mechanical properties. A 70% reduction in elastic modulus was found in Al(18)B(4)O(33) nanowires compared with their bulk counterpart. Al(18)B(4)O(33) nanowires exhibited higher hardness and elastic modulus than Al(4)B(2)O(9) nanowires.     

Dy0.6Tb0.3Pr0.1(Fe0.95Mn0.05)x取向晶体的结构与磁致伸缩

采用Ｃｚｏｃｈｒａｌｓｋｉ方法生长了Ｄｙ０．６Ｔｂ０．３Ｐｒ０．１（Ｆｅ０．９５Ｍｎ０．０５）ｘ（１．８５≤ｘ≤１．９５）取向合金。所有合金主相为立方Ｌａｖｅｓ相结构,择优取向不完整择优取向的方向与Ｘ的大小有关。研究了沿着这些样品的生长方向的磁致伸缩性能以及磁致伸缩性能与压力之间的关系。     

Plasma surface treatments of poly(l-lactic acid) (PLLA) and poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV)

The surfaces of poly(l-lactic acid) (PLLA) and poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV) were modified by oxygen and nitrogen plasma treatments. The physical and chemical surface characteristics were evaluated by contact angle tests, scanning electron microscopy (SEM), atomic force microscopy (AFM), and X-ray photoelectron spectroscopy (XPS). The plasma treatments caused an increase in both contact angle and roughening, altered the surface morphology, inserted polar groups, and, consequently, enhanced the hydrophilicity for both PLLA and PHBV polymers.     

An SANS Study of Decomposition Kinetics in Amorphous Cu_(12.5)Ni_(10)Zr_(41)Ti_(14)Be_(22.5)

Phase decomposition in amorphous Cu12.5Ni10Zr411Ti14Be22.5 alloy as annealed in the super-cooled liquid range was studied by applying small angle neutron scattering (SANS). As annealed between 600 K and 700 K, the alloy was observed to decompose into two new amorphous phases,with the second phase precipitates embedded in the matrix of the first. Long time annealing of the alloy results in crystallization in addition to evolution of the decomposed microstructure.The kinetic diagram of the decomposition and crystallization for this alloy is given. The second phase precipitates have several nanometers in size and occupy a quite low volume fraction. The decomposition of the supercooled liquid in overall temperature range exhibits the features of spinodal reaction.     

Work Functions of Pd_(83.5)Si_(16.5)and Cu_(70)Ti_(30)Glassy Alloys

The work functions before and aftercrystallization of two glassy alloys,Pd_(83.5)Si_(16.5) andCu_(70)Ti_(30) have been measured by means of the con-tact potential difference method in the secondaryelectron field at room temperature under 10~(-5) Pavacuum.The results show that the work functionsof both glassy alloys are higher than those of thecorresponding crystalline alloys.     

Stabilization of Ferromagnetic Order in La(0.7)Sr(0.3)MnO(3)-SrRuO(3) Superlattices

The study of spatially confined complex oxides is of wide interest, since correlated electrons at interfaces might form exotic phases. Here La(0.7)Sr(0.3)MnO(3)/SrRuO(3) superlattices with coherently grown interfaces were studied by structural techniques, magnetization, and magnetotransport measurements. Magnetization measurements showed that ferromagnetic order in ultrathin La(0.7)Sr(0.3)MnO(3) layers is stabilized in the superlattices down to layer thicknesses of at least two unit cells. This stabilization is destroyed, if the ferromagnetic layers are separated by two unit cell thick SrTiO(3) layers. The resistivity of the superlattices showed metallic behavior and was dominated by the conducting SrRuO(3) layers, the off-diagonal resistivity showed an anomalous Hall effect from both SrRuO(3) and La(0.7)Sr(0.3)MnO(3) layers. This shows that the La(0.7)Sr(0.3)MnO(3) layers are not only ferromagnetic but also highly conducting; probably a conducting hole gas is induced at the interfaces that stabilizes the ferromagnetic order. This result opens up an alternative route for the fabrication of two-dimensional systems with long-range ferromagnetic order.     

Fluorescence properties of Dy(3+) doped La(3)Ga(5.5)Nb(0.5)O(14) nanocrystals

The effects of Dy(3+) doping concentration and calcinations on the fluorescence properties of La(3)Ga(5.5)Nb(0.5)O(14) (Dy:LGN) nanocrystals were examined for the first time. High quality Dy:LGN nanocrystals were synthesized by the sol-gel method. The room temperature fluorescence spectra were measured; they showed a yellow emission, which can be attributed to the (4)F(9/2)-(6)H(13/2) transition. The relationship between the relative emission intensity and the doping concentration of the specimens, sintered at different temperatures, is consistent with a Gaussian distribution according a fitted and modified formula. The optimum value of the Dy(3+) doping concentration in LGN nanocrystals is in the range 2.0-2.5%. Moreover, in LGN bulk crystal for laser use, the optimum value, calculated through the obtained formula, is presumed in the range 1.5-2.0%. The fluorescent lifetime of a 2.0% Dy:LGN nanocrystal is quite short, only about 8.5?ns.     

Thermosensitive nanocontainers prepared from poly(N-isopropylacrylamide-co-N-(hydroxylmethyl) acrylamide)-g-poly(lactide)

Thermally-responsive graft copolymer of poly(N-isopropylacrylamide-co-N-(hydroxylmethyl)acrylamide)-g-poly(lactide) was synthesized by ring-opening polymerization of D,L-lactide (LA). The polymerization was initiated by the hydroxy group of poly(N-isopropyl acrylamide-co-N-(hydroxylmethyl) acrylamide), using stannous octoate as catalyst. The resulting polymer was temperature-sensitive and the lower critical solution temperature (LCST) was affected by their composition. The chemical structure and physical properties of the grafted copolymers were investigated by various methods. Nanocontainers formed from the self-assembly of poly(N-isopropylacrylamide-co-N-(hydroxylmethyl) acrylamide)-g-poly(lactide) were characterized by transmission electron microscopy (TEM), and a spherical structure was observed. Dynamic light scattering (DLS) results indicate that the particle size increased with the increase of polylactide content in the copolymer. The properties of this polymer are interesting for both industrial application and fundamental research. In particular it will combine a spatial specificity in a passive manner and a temperature-responsive active targeting mechanism for drug delivery system.     

Amphiphilic zwitterionic poly(dimethylsiloxane) (PDMS)-contained poly(ether amine) (Z-SiPEA) as the responsive polymeric dispersant

We demonstrated here a novel concept of the responsive dispersant based on the amphiphilic zwitterionic poly(ether amine) (Z-SiPEAs), which can control the dispersion of dyes and pigments in water. Z-SiPEAs are composed of short poly (dimethylsiloxane) (PDMS) chain in the backbone and Jeffamine L100 as graft chain. The amino groups in the backbone and carboxyl groups grafted to the backbone make the obtained Z-SiPEAs zwitterionic. Transmission electron microscopy (TEM) and dynamic light scattering (DLS) results revealed that the obtained Z-SiPEAs can self-assemble into nanoparticles in water, which possessed sharp response to temperature, pH, and ionic strength with the tunable clouding point (CP). In the presence of Z-SiPEAs, not only hydrophobic dyes such as Nile Red can be dispersed in water, but the hydrophilic dye Rose Bengal (RB) can be dispersed in unpolar solvents. Further more, Z-SiPEAs can enhance the dispersion of inorganic pigments Titanium White, Iron Red and Chrome Yellow very efficiently in most solvents. It should be noted that the dispersion of organic dyes and inorganic pigments in water can be controlled by temperature in the presence of Z-SiPEAs. 1H NMR and FT-IR revealed the strong coordination between carboxyl groups in Z-SiPEAs and metal atoms of inorganic pigments. These characteristics will give Z-SiPEAs potential as the novel responsive polymeric dispersant.     

预退火对合金Sm_5Fe_(74.3)Nb_(1.5)Si_(11.7)B_(4.5)C_(2.3)Cu_(0.5)的非晶结构影响

用XRS法测定Sm5Fe74.3Nb1.5Si11.7B4.5C2.3Cu0.5非晶合金在相同时间不同温度和在相同温度不同时间预退火条件下的短程有序范围、最近邻原子间距结构参数,从而讨论预退火对非晶结构的影响。结果表明,非晶合金由原始态加热到400oC范围内预退火,非晶短程有序范围会随温度升高而增大,到400oC时达最大值。随温度继续升高,超过400oC时,短程有序范围开始减小,而最近邻原子间距增大。在同一温度500oC不同预退火时间,短程有序范围随时间的延长而增大,最近邻原子间距随时间的增加而减小。     

Flip-Chip p(GaN)-i(GaN)-n(AlGaN) Narrowband UV-A Photosensors

Flip-chip p(GaN)-i(GaN)-n(AlGaN) photosensors with extremely low dark currents were fabricated and characterized. It was found that the sensor with a 0.5-$muhboxm$-thick Si-doped$hboxn^+hbox-Al_0.15hboxGa_0.85hboxN$layer could only detect optical signals with wavelength in between 325 and 360 nm. With an incident wavelength of 355 nm, the authors achieved a peak responsivity of 0.16 A/W at zero bias, which corresponds to an external quantum efficiency of 56%.     

Dumbbell-like PtPd-Fe(3)O(4) Nanoparticles for Enhanced Electrochemical Detection of H(2)O(2)

Dumbbell-like Pt(x)Pd(100-x)-Fe(3)O(4) nanoparticles (NPs) were synthesized and studied for electrocatalytic reduction and sensing of H(2)O(2). In 0.1 M phosphate buffered saline (PBS) solution, the 4-10 nm Pt(x)Pd(100-x)-Fe(3)O(4) NPs showed the Pt/Pd composition-dependent catalysis with Pt(48)Pd(52)-Fe(3)O(4) NPs having the best activity. The Pt(48)Pd(52)-Fe(3)O(4) NPs were tested for H(2)O(2) detection, and their H(2)O(2) detection limit reached 5 nM, which was suitable for monitoring H(2)O(2) generated from Raw 264.7 cells. These dumbbell-like PtPd-Fe(3)O(4) NPs are the most sensitive probe ever reported and can be used to achieve real-time quantitative detection of H(2)O(2) in biological environment for biological and biomedical applications.     

Sr0.7La0.15Ce0.15Fe11.7Zn0.3O19/PAn复合材料的制备及微波吸收性能

用溶胶-凝胶法制备了La、Ce、Zn掺杂锶铁氧体Sr0.7La0.15Ce0.15Fe11.7Zn0.3O19纳米粉晶,再通过原位聚合反应法制备了掺杂锶铁氧体/聚苯胺(PAn)复合材料.用XRD、SEM、FTIR对样品进行表征,用微波网络分析仪测量了样品在2～12.4GHz频率范围的微波反射率(R).研究结果表明,聚苯胺包覆于掺杂锶铁氧体粒子表面,Sr0.7La0.15Ce0.15Fe11.7Zn0.3O19/PAn微波吸收性能优良,具有磁损耗和电损耗协同作用.复合样品厚度为3mm时,10GHz频率位置吸收峰值为-28dB,10>dB吸收带宽为4.7GHz.从R随频率变化的曲线趋势看,最佳匹配厚度为2.6mm,吸收峰值接近-40dB,峰值频率高于12.4GHz,>10dB吸收带宽预计达到5.5GHz.     

Normal-incidence reflectance of crystalline K(6)C(60), Rb(6)C(60), and Cs(6)C(60)

The structure factors and normal-incidence reflectances of the alkali-metal-doped fulleride crystals M(6)C(60) (where M = K, Rb, or Cs) were calculated, and the peak reflectances are in the 2-20% range for incident wavelengths of 9-17 ?, which indicates that C(60) may be a promising transmissive (spacer) material for normal-incidence mirrors that have relatively high normal-incidence reflectance in the x-ray region.