InxGa（1-x）As/GaAs应变单量子阱结构的静压光致发光研究

国家自然科学基金

预注入对Si_(1-x)C_x合金形成的影响

室温下在单晶Si中注入 (0 6— 1 5 )at%的C原子 ,部分样品在C离子注入之前在其中注入2 9Si+ 离子产生损伤 ,然后在相同条件下利用高温退火固相外延了Si1 -xCx 合金 ,研究了预注入对Si1 -xCx 合金形成的影响 .如果注入C离子的剂量小于引起Si非晶化的剂量 ,在 95 0℃退火过程中注入产生的损伤缺陷容易与C原子结合形成缺陷团簇 ,难于形成Si1 -xCx 合金 ,预注入形成的损伤有利于合金的形成 .随着C离子剂量的增大 ,注入产生的损伤增强 ,预注入反而不利于Si1 -xCx 合金的形成 ,但当注入C原子的浓度超过固相外延的溶解度时 ,预注入的影响可以忽略 .退火温度升高到 10 5 0℃ ,无论预注入还是未预注入样品 ,C含量低的合金相仍然保留 ,而C含量高的合金相大部分消失 .

不同剂量C离子注入Si单晶中Si_(1-x)C_x合金的形成及其特征

室温下在单晶Si中注入 (0 6— 1 5 ) %的C原子 ,利用高温退火固相外延了Si1-xCx 合金 ,研究了不同注入剂量下Si1-xCx 合金的形成及其特征 .如果注入C原子的浓度小于 0 6 % ,在 85 0— 95 0℃退火过程中 ,C原子容易与注入产生的损伤缺陷结合 ,难于形成Si1-xCx 合金相 .随注入C原子含量的增加 ,C原子几乎全部进入晶格位置形成Si1-xCx 合金 ,但如果注入C原子的浓度达到 1 5 % ,只有部分C原子参与形成Si1-xCx 合金 .升高退火温度 ,Si1-xCx 合金相基本消失 .

C离子注入Si中Si_(1-x)C_x合金的形成及其稳定性

利用离子注入和高温退火的方法在Si中生长了C含量为0.6%~1.0%的Si1?xCx合金, 研究了不同注入剂量下Si1?xCx合金的形成及其在退火过程中的稳定性. 如果注入剂量小于引起Si非晶化的剂量, 850℃退火后, 注入产生的损伤缺陷容易与C原子结合形成缺陷团簇, 难于形成Si1?xCx合金. 随着注入C离子剂量的增大, 注入产生的损伤增强, 容易形成Si1?xCx合金, 但注入的剂量增大到一定程度, Si1?xCx合金的应变将趋于饱和, 即只有部分C原子进入晶格位置形成合金相. Si1?xCx合金一旦形成, 在950℃仍比较稳定, 而温度高于1 000℃, 合金的应力将部分释放. 随着合金中C原子浓度的升高, 合金的稳定性变差.

Magnetic characterization of Co1-xNixFe2O4 (0 <= x <= 1) nanoparticles prepared by co-precipitation route

Magnetic nanoparticles of Ni-doped cobalt ferrite [Co1-xNixFe2O4(0 <= x <= 1)] synthesized by coprecipitation route have been studied as a function of doping concentration (x) and particle size. The size of the particles as determined by X-ray diffractometer (XRD) and transmission electron microscope (TEM) analyses was found in the range 12-48 nm. The coercivity (H-C) and saturation magnetization (M-S) showed a decreasing behavior with increasing Ni concentration. M-S of all the samples annealed at 600 degrees C lies in the range 65.8-13.7 emu/gm. Field-cooled (FC) studies of the samples showed horizontal shift (exchange bias) and vertical shift in the magnetization loop. Strong decrease in exchange bias (H-b) and vertical shift (delta M) was found for low Ni concentrations while negligible decrease was found at higher concentrations. The presence of exchange bias in the low Ni-concentration region has been explained with reference to the interface spins interaction between a surface region (with structural and spin disorder) and a ferrimagnetic core region. M(T) graphs of the samples showed a decreasing trend of blocking temperature (T-b) with increasing Ni concentration. The decrease of T-b with increasing Ni concentration has been attributed to the lower anisotropy energy of Ni+2 ions as compared to Co+2 that increases the probability of the jump across the anisotropy barrier which in turn decreases the blocking temperature of the system.

General SU(2)(L) x SU(2)(R) x U(1)(EM) sigma model with external sources, dynamical breaking and spontaneous vacuum symmetry breaking

We give a general SU(2)(L) x SU(2)(R) x U(1)(EM) sigma model with external sources, dynamical breaking and spontaneous vacuum symmetry breaking, and present the general formulation of the model. It is found that sigma and pi(0) without electric charges have electromagnetic interaction effects coming front the internal structures. A general Lorentz transformation relative to external sources J(gauge) - (J(A mu) J(A mu)(kappa)) derived, using the general Lorentz transformation and the four-dimensional current of nuclear matter of the ground si ate with J(gauge) = 0, we give the four-dimensional general relations between the different currents of nuclear matter systems with J(gauge) not equal 0 and those with J(gauge) = 0. The relation of the density's coupling with external magnetic field is derived, which conforms well to dense nuclear matter in a strong magnetic field. We show different condensed effects in strong interaction about fermions and antifermions, and give the concrete scalar and pseudoscalar condensed expressions of sigma(0) and pi(0) bosons. About different dynamical breaking and spontaneous vacuum symmetry breaking, the concrete expressions of different mass spectra are obtained in field theory. This paper acquires the running spontaneous vacuum breaking value sigma'(0), and obtains the spontaneous vacuum breaking in tenus of the running sigma'(0), which make nucleon, sigma, and pi particles gain effective masses. We achieve both the effect of external sources and nonvanishing value of the condensed scalar and pseudoscalar paticles. It is deduced that the masses of nucleons, sigma and pi generally depend on different external sources.

Structures and electrochemical characteristics of Ti0.26Zr0.07V0.24Mn0.1Ni0.33Mox (x=0-0.1) hydrogen storage alloys

Microstructures and electrochemical properties of Ti0.26Zr0.07V0.21Mn0.1Ni0.33Mox (x=0,0.025,0.05,0.075, 0.10) electrode alloys have been investigated. The results of XRD analysis show that the alloys are mainly composed of V-based solid solution phase with body centered cubic (bcc) structure and C14 Laves phase with hexagonal structure. The addition of Mo element can imp ove the activation characteristics, maximum discharge capacity and cyclic durability for the electrode alloys

Mo掺杂对高纯Ce_(1-x)Nd_xO_(2-x/2)(x=0.10,0.15)体系烧结温度及晶界电性能的影响

用柠檬酸硝酸盐法制备高纯Ce1-xNdxO2-x/2(x=0.10,0.15)固溶体,加入摩尔分数为5%的Mo,研究了Mo掺杂对烧结温度、结构及电性能的影响.通过X射线衍射、电感偶合等离子体和场发射扫描电镜等手段对氧化物进行了结构表征,采用交流阻抗谱测试其电性能.柠檬酸硝酸盐法制备的前驱体经1450℃烧结24 h得到致密度大于96%的陶瓷材料;加入5%Mo,在1250℃下烧结8 h即可达到理想的致密度(>95%).加入Mo在烧结过程中可加快晶界迁移,促进晶粒生长,显著提高了晶界电导率.在600℃时Ce0.85Nd0.15O1.925的晶界电导率为2.56 S/m,加入Mo后材料的电导率增加到5.62 S/m.

Microstructures and mechanical properties of as-cast Mg–5Al–0.4Mn–xNd (x=0, 1, 2 and 4) alloys

Mg-5Al-0.4Mn-xNd (x=0, 1, 2 and 4wt.%) alloys were prepared by metal mould casting method. The microstructures and mechanical properties were investigated. The results demonstrated that Al11Nd3 phase was formed and mainly aggregated along the grain boundaries with the addition of Nd. Meanwhile, the grain sizes were greatly reduced with the increasing Nd content.

Microstructure and mechanical properties of Mg-4.5Zn-xNd (x=0, 1 and 2, wt%) alloys

Microstructure and mechanical properties of Mg-4.5Zn-xNd (x = 0, 1 and 2, wt%) alloys heat-treated at 603 K for 2 It have been investigated. T-phase (an Mg-Zn-Nd ternary phase) was observed in the Nd containing alloys. The optimal mechanical properties were obtained in the Mg-4.5Zn-1Nd alloy, and the ultimate tensile strength and yield strength were 228 and 79 MPa, respectively. Through comparing with the Mg-4.5Zn alloy, the increments of ultimate tensile strength and yield strength were 51 and 17 MPa.

Solvothermal synthesis of well-dispersed MF2 (M = Ca, Sr, Ba) nanocrystals and their optical properties

MF2 (M = Ca, Sr, Ba) nanocrystals (NCs) were synthesized via a solvothermal process in the presence of oleic acid and characterized by x-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared (FT-IR) spectra, UV/vis absorption spectra, photoluminescence (PL) excitation and emission spectra, and lifetimes, respectively. In the synthetic process, oleic acid as a surfactant played a crucial role in confining the growth and solubility of the MF2 NCs. The as-prepared CaF2, SrF2 and BaF2 NCs present morphologies of truncated octahedron, cube and sheet in a narrow distribution, respectively.