共查询到20条相似文献,搜索用时 62 毫秒
1.
Ludmila G. Sevastyanova Olga K. Gulish Vladimir A. Stupnikov Vladimir K. Genchel Oleg V. Kravchenko Boris M. Bulychev Roman A. Lunin Valeriy P. Tarasov 《Central European Journal of Physics》2012,10(1):189-196
Compounds with the general formula Mg1−x
Al
x
B2 were obtained by two-step ceramic synthesis. All compounds were characterized by X-ray diffraction, NMR spectroscopy, and
by four point probe resistivity measurements in various magnetic fields method. The diborides unit cell parameters were determined
as a function of the Al mole fraction. With the vaues of x up to 0.40 (where x is the composition of the stock prepared for sintering), the unit cell parameters of Mg1−x
Al
x
B2 are similar to those of pure MgB2 and the superconducting transition temperature was lowered. For stock compositions of 0:25 ≤ x ≤ 0:60, the products contain a superstructure, also superconducting phase, which becomes the only product at x = 0:50, and at x > 0:60 this phase is replaced by AlB2-based solid solutions. 相似文献
2.
在白宝石(sapphire)衬底上低温外延生长出了MgxZn1-xO晶体薄膜.x射线衍射(XRD)及能量色散x射线(EDX)分析表明,MgxZn1-xO薄膜的晶体结构依赖于薄膜中Mg的组分x,随着Mg组分的增大,MgxZn1-xO薄膜的结构从与ZnO晶体一致的六方结构转变为与MgO晶体一致的立方结构.对MgxZn1-xO薄膜的紫外透
关键词:
电子束蒸发反应
xZn1-xO晶体薄膜')" href="#">MgxZn1-xO晶体薄膜
结构和光学性能 相似文献
3.
G. Epurescu R. Birjega A. C. Galca 《Applied Physics A: Materials Science & Processing》2011,104(3):889-893
Thin films of Mg
x
Zn1−x
O and Mg
x
Zn1−x
O doped with nitrogen were deposited by Radio Frequency plasma beam assisted Pulsed Laser Deposition (RF-PLD) in oxygen or
oxygen-nitrogen discharge with different nitrogen/oxygen ratios. A Nd:YAG laser working at a wavelength of 266 nm, having
a 10 Hz repetition rate was used for the depositions. The energy density of the incident beam was 3 J/cm2 and the RF power was set to 100 W for all the samples. X-ray Diffraction (XRD) and Spectroscopic Ellipsometry (SE) were employed
to investigate the samples. The degree of crystallinity is fount to decrease with increasing the Mg concentration, while the
solubility of Mg in ZnO increases by 30% in the N-doped Mg
x
Zn1−x
O thin films grown by RF-PLD. Segregation of MgO phase at a Mg concentration of 30% for Mg
x
Zn1−x
O thin film is detected both by XRD and SE. The band gap of the samples increases from 3.37 up to 3.57 eV with increasing
the Mg concentration and the nitrogen/oxygen ratio for each Mg concentration. A dependence of the dielectric function (refractive
index) on both stoichiometry and degree of crystalinity is also found, the refractive index having values between 1.7 and
2 in visible spectral range. 相似文献
4.
利用溶胶-凝胶法成功制备了Mg掺杂Pb0.4Sr0.6MgxTi< sub>1-xO3-x薄膜,利用x射线衍射仪对薄膜的物相和结构进行了分析, 用扫描电子显微镜对薄膜的形貌和断面等进行了观察.研究结果表明,薄膜以立方钙钛矿为 晶相,薄膜中晶相以团聚状颗粒存在,晶相含量受热处理条件和Mg的掺杂量所控制.Mg掺杂 对Pb0.4Sr0.6MgxTi1-xO3-x 薄膜晶相含量的影响与钙钛矿中的氧空位缺陷相关.在一定的掺杂范围内,由掺杂引起晶相 的晶格畸变较小时,体系掺Mg平衡了晶体内本征氧空位引入的电荷不平衡,使晶相更为稳定 ,析晶能力提高,晶体形成量随掺杂浓度的提高而提高.当掺杂浓度达到一定量时, 随着Mg 掺杂浓度增加,一方面使形成晶体时杂质浓度增加造成参与形成晶相的组成含量下降,另一 方面使进入钙钛矿结构的Mg增加,氧空位大量增加使畸变程度提高,形成的晶相不稳定,析 晶能力下降,晶体含量随掺杂Mg浓度的增加而不增反降.在相同条件下制备的Pb0.4Sr0.6MgxTi1-xO3-x薄膜中Mg掺量约为 x=0.01时,得到的钙钛矿相含量最高,本征氧缺陷所带入的正电荷和Mg引入时带入的负电荷 间达到平衡.此外,Mg的掺入还影响到析晶与热处理过程之间的关系.在高Mg掺量范围,Mg含 量越高,形成的晶相越不稳定,热处理时间越长,使热处理过程中分解的晶相量越多,随Mg 掺量越高和热处理时间越长,薄膜中晶相含量越低.
关键词:
溶胶-凝胶法
PST薄膜
Mg掺杂
晶相形成 相似文献
5.
A. Gómez-Herrero E. Urones-Garrote A.J. López L.C. Otero-Díaz 《Applied Physics A: Materials Science & Processing》2008,92(1):97-102
Two Hispanic Terra Sigillata pottery samples from different workshops – Tricio and Andújar – have been characterized by means
of electron microscopy and associated techniques and X-ray diffraction data. The combined information from transmission electron
microscopy images, electron diffraction patterns and microchemical analysis has revealed the nature and distribution of the
precipitates of the ceramic piece slip, which is a very important part in the characterization of these kind of ceramic wares.
Both samples present homogeneously dispersed α-Fe2-xAlxO3 (corundum-type structure) particles embedded in a glassy matrix of SiO2-Al2O3. The Si : Al ratio of the matrix is different in each case, with a higher Al content in the Andújar ceramic sample. Crystallites
of spinel – Mg(Al,Fe)2O4 – and Al2-xFexO3 are also detected in both cases. In addition, ilmenite phase (FeTiO3) and TiO2 (rutile-type) were observed less frequently.
PACS 68.37.Lp; 79.20.Uv; 61.10.Nz 相似文献
6.
Yogendra K. Gautam Amit K. ChawlaRajan Walia R.D. AgrawalRamesh Chandra 《Applied Surface Science》2011,257(14):6291-6295
Structural and optical properties of pure Mg thin film coated with Pd have been investigated. Pd-capped Mg thin films had been prepared by DC magnetron sputtering. This work presents an ex situ study on hydrogenation and dehydrogenation kinetics of Pd/Mg films at different conditions using XRD, AFM and optical spectrophotometer. We have succeeded to load thin films of Mg to MgH2 at normal temperature and normal pressure of hydrogen gas. In hydrogenation, α-MgH2 phase of magnesium hydride was observed in hydrogenated films at 200 °C and γ-MgH2 at 250 °C respectively. The desorption kinetics in vacuum also revealed the phase transformation α-MgH2 to γ-MgH2. A reflectance change was observed in hydrogenated films in comparison of as deposited thin film. Hydrogenated (H loaded) samples were observed partially transparent in comparison of as deposited. 相似文献
7.
The microstructures and tensile properties of Mg–Al2Ca–Mg2Ca in situ composites (Mg–17Al–8Ca, Mg–14Al–11Ca and Mg–12.5Al–12.5Ca) with different Ca/Al ratios have been studied in both as-cast and extruded conditions. The results indicated that by increasing Ca/Al ratio, new Mg2Ca intermetallic introduces to the Al2Ca phase in eutectic structure. Computer-aided cooling curve analysis confirmed the formation of these phases during solidification. Extrusion process not only altered the size of large bulk Al2Ca intermetallic, but also changed the size and morphology of intermetallics in eutectic structure considerably. The results showed that with increasing Ca/Al ratio, tensile properties of cast composites changes slightly, but significant enhancement is observed after extrusion process. The strength and elongation values of Mg–12.5Al–12.5Ca (Ca/Al = 1) alloy improved from 166 MPa and 2% in as-cast condition to 465 MPa and 12% in hot-extruded condition. The reason for the improved toughness may be attributed to the formation of finer and well-dispersed distribution of hard (Al2Ca) and ductile (Mg2Ca) phases. It was found that hot extrusion easily deforms ductile Mg2Ca phase in comparison with Al2Ca phase. In as-extruded condition, there are more very fine dimples than as-casted condition because extrusion process leads to formation of fragmented tiny particles and more uniformity distribution of Al2Ca particles. 相似文献
8.
高组份Al值的AlxGa1-x As和AlxGa1-x As/GaAs/AlxGa1-xAs/GaAs多层结构的MOCVD生长 总被引:1,自引:1,他引:0
用自制常压MOCVD系统,在半绝缘GaAs衬底上生长高Al组份AlxGa1-xAs(其x值达0.83),和AlxGa1-xAs/GaAs/AlxGa1-xAs/GaAs多层结构,表面镜面光亮。生长层厚度从几十到十几μm可控,测试表明外延层晶格结构完整,x值调节范围宽,非有意掺杂低,高纯GaAs外延层载流子浓度n300K=1.7×1015cm-3,n77K=1.4×1015cm-3,迁移率μ300K=5900cmcm2/V.S,μ77K=55500cm2/V.S。用电子探针,俄歇能谱仪测不出非有意掺杂的杂质,各层间界面清晰平直。 对GaAs,AlGaAs生长层表面缺陷,衬底偏角生长温度及其它生长条件也进行了初步探讨。 相似文献
9.
用真空电子束蒸发制备了MnBixAl0.15薄膜.当0.4≤x≤0.7时,MnBixAl0.15薄膜的Kerr角与MnBix薄膜相比有显著增大;而当x>0.7时,MnBixAl0.15的Kerr角则比MnBix的要不,633nm波长测量时,MnBi0.5Al0.15的Kerr角为2.75°,而相对应的MnBi0.5薄膜只有1.56°.MnBi05Al0.15薄膜的室温饱和磁化强度Ms为3×105A/m,比MnBi0.5薄膜的Ms(4×105A/m)要小.推测当0.4≤x≤0.7时,Al可能部分占据Bi空位和部分取代Mn位,由于晶格收缩使得Mn 3d电子与Bi 6p电子的杂化概率增大,从而导致其Kerr效应增强.
关键词: 相似文献
10.
11.
MgxZn1-xO thin films have been prepared on silicon substrates by radio
frequency magnetron sputtering at 60℃. The thin films have hexagonal
wurtzite single-phase structure and a preferred orientation with the c-axis
perpendicular to the substrates. The refractive indices of MgxZn1-xO films
are studied at room temperature by spectroscopic ellipsometry over the wavelength
range of 400--760\,nm at the incident angle of 70℃. Both absorption
coefficients and optical band gaps of MgxZn1-xO films are determined by
the transmittance spectra. While Mg content is increasing, the absorption edges of
MgxZn1-xO films shift to higher energies and band gaps linearly increase
from 3.24.eV at x=0 to 3.90\,eV at x=0.30. These results provide important
information for the design and modelling of ZnO/ MgxZn1-xO heterostructure
optoelectronic devices. 相似文献
12.
The photoluminescent (PL) spectra of Zn1-xCdxO (0≤x≤0.53) alloy films were obtained successfully. A new explanation from the viewpoint of band structure is brought forward
to comprehend the PL nature of the alloy films. According to this explanation, the near-band-energy emissions of the Zn1-xCdxO (x>0) films are caused by the radiative transitions between the Zn4s–Cd5s hybrid level and the O2p level, and the broadenings
of the two levels are responsible for the gradually increased line width of the PL peak of the film; Zn3d and Cd4d orbital
levels have great effects on the band-gap variations of the alloys. In addition, a quadratic equation is put forward to depict
the relationship between the band gaps Eg of the alloys and their Cd contents x, i.e. Eg(x)=3.30-1.22x+1.26x2 (0≤x≤0.53).
PACS 78.55.-m; 78.55.Et; 81.15.Cd 相似文献
13.
利用电感耦合等离子体(ICP)装置对分子束外延(MBE)法在Sapphire衬底上生长的Zn1-xMgxO薄膜的Mg组分进行了测试. 经理论分析,得到使用1次和2次检量式所确定的Zn1-xMgxO薄膜中的Mg组分的差异. 将采用1次检量式的ICP测定与EPMA测定结果进行对照,表明当Mg组分x≤0.5时二者的测试结果相当一致,由此证明ICP测试结果的正确性.
关键词:
ZnMgO薄膜
Mg组分
分子束外延(MBE)
电感耦合等离子体(ICP) 相似文献
14.
In2(Se1-xTex)3 polycrystalline films were prepared by a dual-source thermal evaporation technique. The depositions onto glass and SnO2-coated glass substrates were carried out in a vacuum chamber and followed by an annealing in neutral ambient (Ar or N2). The structural, morphological and compositional studies of the films were made by X-ray diffraction, energy-dispersive
X-ray analysis, X-ray photoelectron spectroscopy, scanning electron microscopy, Raman scattering and optical transmission.
Optimum conditions are investigated for the formation of the ternary compound In2(Se1-xTex)3 in order to tune the band gap by changing the Te concentration. The film properties as a function of Te amount are discussed.
It is shown that single-phase, textured and homogeneous layers of In2(Se1-xTex)3 can be grown with x≤0.2 at optimal deposition and heat treatment conditions. For x≅0.17 these films showed an energy band
gap of about 1.45 eV and an electrical conductivity at room temperature six orders of magnitude higher than that of the binary
γ-In2Se3 thin films.
Received: 9 July 1999 / Accepted: 25 November 1999 / Published online: 13 July 2000 相似文献
15.
P. Kumar S. Kanakaraju D.L. DeVoe 《Applied Physics A: Materials Science & Processing》2007,88(4):711-714
A study of AlxGa1-xAs as a sacrificial film for surface micromachining is presented. AlxGa1-xAs etch rate and selectivity are measured over a range of aluminum mole fractions and HF etchant concentrations during the
release of structural features up to 500 μm in width. The etch process is found to be diffusion limited, with an inverse power
law relationship between etch depth and etch rate. Excellent selectivity greater than 105 is achieved between sacrificial AlAs and structural GaAs, even for long etches up to 250 μm in length. Compared with previous
studies of AlxGa1-xAs etching for epitaxial liftoff processing, measured etch rates for surface micromachining are approximately an order of
magnitude lower, primarily due to the longer effective etch lengths required. However, unlike epitaxial liftoff, AlxGa1-xAs surface micromachining is compatible with higher HF concentrations which can provide comparable overall etch rates, with
important implications for AlGaAs MEMS fabrication.
PACS 81.05.Ea; 85.85.+j 相似文献
16.
J.T. Devaraju B.H. Sharmila S. Asokan K.V. Acharya 《Applied Physics A: Materials Science & Processing》2002,75(4):515-518
The electrical switching behaviour of As45Te55-xInx (5≤x≤15) and As50Te50-xInx (2.5≤x≤11.5) has been studied over a wide range of compositions. These glasses are found to exhibit threshold switching.
The composition dependence of switching voltage (Vt) has been found to exhibit a change in slope and a local minimum at compositions x=10 and 12.5 for As45Te55-xInx and x=7.5 and 10.8 for As50Te50-xInx, respectively. The slope change in Vt verses x and the local minimum have been identified using two network topological effects, namely the rigidity percolation
threshold and the chemical threshold.
Received: 23 August 2001 / Accepted: 27 August 2001 / Published online: 11 February 2002 相似文献
17.
The kinetic properties of ferromagnetic Ni3Al1 − x
Mn
x
alloys with
x
≤ 0.6 are studied at T ≤ 800 K and H ≤ 7 MA/m. The behavior of the electrical resistivity, the thermopower, the magnetoresistance, the Hall effect, and the spontaneous
Hall effect are analyzed in the range of transition from band (Ni3Al) to spinlocalized (Ni3Mn) ferromagnetism at x ∼ 0.15. 相似文献
18.
S.C. Su Y.M. Lu Z.Z. Zhang D.Z. Shen J.Y. Zhang X.W. Fan 《Applied Surface Science》2008,254(15):4886-4890
The Zn1−xMgxO thin films were grown on Al2O3 substrate with various O2 flow rates by plasma-assisted molecular beam epitaxy (P-MBE). The growth conditions were optimized by the characterizations of morphology, structural and optical properties. The Mg content of the Zn1−xMgxO thin film increases monotonously with decreasing the oxygen flux. X-ray diffractometer (XRD) measurements show that all the thin films are preferred (0 0 2) orientated. By transmittance and absorption measurements, it was found that the band gap of the film decreases gradually with increasing oxygen flow rate. The surface morphology dependent on the oxygen flow rate was also studied by field emission scanning electron microscopy (FE-SEM). The surface roughness became significant with increasing oxygen flow rate, and the nanostructures were formed at the larger flow rate. The relationship between the morphology and the oxygen flow rate of Zn1−xMgxO films was discussed. 相似文献
19.
The synthesis and characterization are reported for the cubic spinel titanate Mg(2−x)NixTiO4 (x≤0.25) and Mg(2−x)MnxTiO4 (x≤1). Single phase samples were observed for Mg(2−x)NixTiO4 and with x≤0.4 for Mg(2−x)MnxTiO4. AC measurements were carried out on four different compositions (x=0.01, 0.03, 0.04 and 0.15) in the Mg(2−x)NixTiO4 series and for Mg1.9Mn0.1TiO4. For all these compounds, increasing conductivity with temperature and Arrhenius conductivity dependence are observed, the
activation energy is around 0.28 eV for the Ni compounds and is 0.184 eV for Mg1.9Mn0.1TiO4. The DC conductivity was recorded over a range of oxygen partial pressures (10−19 to 1 atm) at 930 °C. The Mg(2−x)NixTiO4 compounds show a n-type behaviour whereas the Mg(2−x)MnxTiO4 show a p-type behaviour at high p(O2) and n-type at low p(O2). The stability under reduced conditions was checked and discussed for the different synthesized compounds.
Paper presented at the 5th Euroconference onSolid State Ionics, Benalmádena, Spain, Sept. 13–20, 1998. 相似文献
20.
用射频磁控溅射法在80℃的衬底温度下制备出MgxZn1-xO(0≤x ≤030)薄膜.x射线 衍射(XRD)结果表明,MgxZn1-xO薄膜为单相六角纤锌矿结构, 没有形成任何显著 的MgO分离相,MgxZn1-xO薄膜的择优取向平行于与衬底垂直的 c轴;c轴晶格常数随着Mg含量的增加逐渐减小.在MgxZn1-xO薄膜的光透射谱中出现 锐利的吸收边,由透 射谱估算出MgxZn1-xO薄膜的带隙宽度由332eV(x=0)线性地 增加到396eV(x=030).
关键词:
xZn1-xO薄膜')" href="#">MgxZn1-xO薄膜
射频磁控溅射
Mg含量 相似文献