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21.
利用NaCI:KCI:NaF=2:2:1(摩尔比)的碱金属卤化物混合体系为载体,Na2SiF6:Si=8:2粉末为渗硅剂,SiO2为助渗剂,800℃下渗硅5h可实现在AISI3O4不锈钢表面形成Fe3Si型硅化物渗层.采用万能材料试验机进行轴向拉伸试验,用附带能量色散谱仪的扫描电子显微镜进行断面分析.结果表明,渗层中的大空洞为包盐孔洞. 相似文献
22.
采用不同硅化工艺制备了NiSi薄膜并用剖面透射电镜(XTEM)对样品的NiSi/Si界面进行了研究.在未掺杂和掺杂(包括As和B)的硅衬底上通过物理溅射淀积Ni薄膜,经快速热处理过程(RTP)完成硅化反应.X射线衍射和喇曼散射谱分析表明在各种样品中都形成了NiSi.还研究了硅衬底掺杂和退火过程对NiSi/Si界面的影响.研究表明:使用一步RTP形成NiSi的硅化工艺,在未掺杂和掺As的硅衬底上,NiSi/Si界面较粗糙;而使用两步RTP形成NiSi所对应的NiSi/Si界面要比一步RTP的平坦得多.高分辨率XTEM分析表明,在所有样品中都形成了沿衬底硅〈111〉方向的轴延-NiSi薄膜中的一些特定晶面与衬底硅中的(111)面对准生长.同时讨论了轴延中的晶面失配问题. 相似文献
23.
Pure Fe with coverage of 0.5-2.0 nm was deposited on Si (111) 7×7 surfaces by reactive deposition epitaxy (RDE) in an integrated ultrahigh vacuum (UHV) system. Transmission electron microscopy (TEM) confirmed that the as-deposited epitaxial phase exhibits rod-like and equilateral triangular morphology. The as-deposited phase was identified as c-FeSi2 by electron diffraction and high-resolution transmission electron microscopy. It was found that there exists lattice distortion in epitaxial c-FeSi2 phase. Upon annealing at 1073 K, the metastable c-FeSi2 transforms into equilibrium β-FeSi2 phase, the latter inherits completely the morphology of c-FeSi2 phase. Based on RDE and subsequent annealing, a new fabrication technique to grow rod-like semiconducting β-FeSi2 on a Si substrate has been proposed in the present work. 相似文献
24.
Pierre Tomasini 《Materials Science in Semiconductor Processing》2013,16(4):1086-1089
Methyldichlorosilane (CH3SiHCl2) is compared to methylsilane (CH3SiH3) for vapor phase epitaxy of cubic silicon - carbon (NO :) (Si:C) alloys on Si (001). Parameters of interest are growth rate, percent carbon and crystallinity. Carbon incorporation efficiency and experimental window for epitaxial growth are similar for both precursors. The two precursors differ in Si contribution to the film growth rate. 相似文献
25.
26.
《Intermetallics》2017
The cobalt silicide CoSi seems a suitable material for thermoelectricity: it is inexpensive and non-toxic, but its thermal conductivity is large. Forming CoSi-based alloys by replacing part of Co or Si with a heteroatom M can change electronic properties and improve thermoelectric performances. The insertion energy of different CoSi-based alloys containing abundant, inexpensive and non-toxic elements was estimated by using DFT calculations. Several alloys were synthesized using arc-melting or powder reaction and then characterized using X-Rays powder Diffraction (XRD) and Electron Micro Probe Analysis (EMPA) to determine the limit of solubility of these heteroatoms within CoSi. DFT predictions of solubility limit were in qualitative agreement with experimental results. Vibrational and thermoelectric properties were measured for alloys containing highly soluble elements (Mn and Cr) but also poorly soluble ones (Ti and V). These new CoSi-based alloys, studied for the first time for thermoelectric applications, do not exhibit a notable improvement of the performances. 相似文献
27.
《Ceramics International》2016,42(15):16758-16765
The study focuses on investigation of the combustion kinetics and mechanisms, as well as the phase- and structure formation processes, during elemental synthesis of ceramics based on zirconium diboride and silicide doped with aluminum. The effect of the degree of dilution with an inert component and initial temperature T0 on the combustion kinetics of the Zr–Si–Al–B mixture is studied. An increase in T0 in the range of 298–700 K causes a directly proportional rise in the combustion temperature Tc and rate Uc, which demonstrates that staging of the reactions of formation of zirconium boride and silicide remains invariant. The effective activation energy Eeff of the combustion process is 225 kJ/mol, suggesting that the liquid-phase processes have a decisive effect on the reaction kinetics. The interaction of zirconium with boron and silicon runs through the Zr–Si–Al–B melt that is formed in the combustion zone. Staging of chemical transformations during phase and structure formation of SHS products is studied. The primary ZrB2 grains crystallize from the melt in the combustion zone; the ZrSi silicide phase is formed with a delay of no longer than 0.5 s. Compact ceramics with composition ZrB2–ZrSi–ZrSi2–ZrSiAl2 synthesized by forced SHS- pressing showing a great potential for high-temperature applications both as a construction material and as a precursor for ion-plasma deposition of coatings. 相似文献
28.
Hongjun FengJungang Hou Yuanfang Qu Dan ShanGuohua Yao 《Journal of Alloys and Compounds》2012,512(1):12-16
Rare-earth doped barium zirconium titanate (BZT) ceramics, Ba(Zr0.25Ti0.75)O3 + xCeO2, (x = 0-1.5 at%) were obtained by a solid state reaction route. Perovskite-like single-phase compounds were confirmed from X-ray diffraction data and the lattice parameters were refined by the Rietveld method. It is found that, integrating with the lattice parameters and the distortion of crystal lattice, there is an alternation of substitution preference of cerium ions for the host cations in perovskite lattice. Morphological analysis on sintered samples by scanning electron microscopy shows that the addition of rare-earth ions affects the growth of the grain and remarkably changes the grain morphology. The effect of rare-earth addition to BZT on dielectric and electrical properties is analyzed. High values of dielectric tunability are obtained for cerium doped BZT. Especially, the experimental results on the effect of the contents of rare-earth addition on the resistivity of BZT ceramics were investigated, demonstrating that the samples with x = 0.4 and x = 0.6 could be semiconducting in air atmosphere. 相似文献
29.
Junying Liu Rui Zhang Itaru Osaka Sarada Mishra Anna E. Javier Detlef‐M. Smilgies Tomasz Kowalewski Richard D. McCullough 《Advanced functional materials》2009,19(21):3427-3434
New solution processable 4‐(2‐hexyldecan)‐4H‐bisthieno[2,3‐d:3′,2′‐b]pyrrole and 4,4′‐dialkyl‐2,2′‐bithiazole‐based copolymers (PBTzDTPs) are synthesized with excellent FET performance. These novel copolymers have considerable potential in printable electronics as they have high charge carrier mobilities, excellent air stability, good solution processibility, and no requirement for post‐deposition thermal annealing, all requirements for this field of application. The thin film transistors fabricated from PBTzDTPs achieve field effect mobilities as high as 0.14 cm2 V?1 s?1 with current on/off ratios up to 106 without thermal annealing. In addition, the devices exhibit stable performance in air, showing no significant degradation over 60 days. Moreover, the polymers described here provide an excellent example of the systems in which higher mobility performance does not require higher crystalline, long‐range ordered structures. Such a system appears to be particularly promising for rapid fabrication techniques, where kinetic conditions usually prevent the development of long‐range order. 相似文献
30.
《Ceramics International》2020,46(4):4595-4601
The effects of the vacancies on the structural stability, elastic constants, elastic moduli, brittle-to-ductile transition and electronic properties of Tantalum Silicide (TaSi2) are investigated in detail by first-principles calculations. The values of vacancy formation energy confirm that the perfect TaSi2 and TaSi2 with different atomic vacancies can exhibit the structural stability at ground state. It is found that Ta atom vacancies are more stable than Si atom vacancies in TaSi2 with vacancies. The elastic constants and elastic moduli describe the mechanical behavior for TaSi2 and TaSi2 with vacancies. The different atomic vacancies weaken the elastic stiffness for TaSi2. But the values of B/G confirm that the brittle-to-ductile transition occurs with different atomic vacancies for TaSi2. Although these vacancies make the shear and volume deformation resistance of TaSi2 weaker, they obviously improve the brittle behavior of TaSi2. The difference charge density and electronic structures are calculated to discuss and analyze the structural stability and mechanical properties for the perfect TaSi2 and TaSi2 with vacancies. 相似文献