Structural characterization and thermal stability of W/Si multilayers

1993 ◽  
Vol 8 (10) ◽  
pp. 2600-2607 ◽  
Author(s):  
M. Brunel ◽  
S. Enzo ◽  
M. Jergel ◽  
S. Luby ◽  
E. Majkova ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Layer Thickness ◽  
Thickness Ratio ◽  
X Ray Diffraction ◽  
Cross Sectional ◽  
X Ray ◽  
Layer Thickness Ratio ◽  
Transmission Electron ◽  
Thermal Stability Of ◽  
Beam Deposition

Tungsten/silicon multilayers with tungsten layers of a thickness of 1–2 nm were prepared by means of electron beam deposition. Their structure and thermal stability under rapid thermal annealing were investigated by a combination of x-ray diffraction techniques and cross-sectional transmission electron microscopy. The crystallization behavior was found to depend on the interdiffusion and mixing at the tungsten/silicon interfaces during deposition as well as during annealing. The as-deposited tungsten/silicon multilayers were amorphous and remained stable after annealing at 250 °C/40 s. Interdiffusion and crystallization occurred after annealing all samples from 500 °C/40 s up to 1000 °C/20 s. By performing the same heat treatment in the tungsten/silicon multilayers, the formation of body-centered cubic W was observed with a layer thickness ratio δW/δsi = 1, whereas tetragonal WSi2 was detected in tungsten/silicon multilayers with a layer thickness ratio of δw/δsi ∼0.25. This dependence of the crystallization products on the layer thickness ratio δw/δsi originates from the different phenomena of interdiffusion and mixing at the tungsten/silicon interfaces. The possible formation of bcc tungsten as a first stage of crystallization of tungsten-silicon amorphous phase, rich in tungsten, is discussed.

Thermal Stability of Strained Si on Relaxed Si1−xGex Buffer Layers

2001 ◽  
Vol 686 ◽  
Author(s):  
P.M. Mooney ◽  
S.J. Koester ◽  
J.A. Ott ◽  
J.L. Jordan-Sweet ◽  
J.O. Chu ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Layer Thickness ◽  
Buffer Layers ◽  
Misfit Dislocations ◽  
X Ray Diffraction ◽  
Strained Si ◽  
X Ray ◽  
Dislocation Glide ◽  
Transmission Electron ◽  
Thermal Stability Of

AbstractThe thermal stability of strained Si on relaxed Si1−xGex structures annealed at 1000 °C was investigated using high-resolution x-ray diffraction, Raman spectroscopy and transmission electron microscopy. Interdiffusion at the Si/Si1−xGex interface is negligible for annealing times <30 sec and is independent of the initial Si layer thickness and the composition of the Si1−xGex layer. In all cases the Si layers remained nearly fully strained, but a significant density of misfit dislocations was seen in layers that exceeded the critical thickness for dislocation glide. The Si layer thickness could be measured for layers as thin as 7 nm.

Formation and Thermal Stability of Nd0.32Y0.68Si1.7 Layers Formed by Channeled Ion Beam Synthesis

1998 ◽  
Vol 514 ◽  
Author(s):  
M. F. Wu ◽  
A. Vantomne ◽  
S. Hogg ◽  
H. Pattyn ◽  
G. Langouche ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Ion Beam ◽  
Hexagonal Structure ◽  
Orthorhombic Structure ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Good Crystalline Quality ◽  
Ion Beam Synthesis ◽  
Thermal Stability Of

ABSTRACTThe Nd-disilicide, which exists only in a tetragonal or an orthorhombic structure, cannot be grown epitaxially on a Si(111) substrate. However, by adding Y and using channeled ion beam synthesis, hexagonal Nd0.32Y0.68Si1.7 epilayers with lattice constant of aepi = 0.3915 nm and cepi = 0.4152 nm and with good crystalline quality (χmin of Nd and Y is 3.5% and 4.3 % respectively) are formed in a Si(111) substrate. This shows that the addition of Y to the Nd-Si system forces the latter into a hexagonal structure. The epilayer is stable up to 950 °C; annealing at 1000 °C results in partial transformation into other phases. The formation, the structure and the thermal stability of this ternary silicide have been studied using Rutherford backscattering/channeling, x-ray diffraction and transmission electron microscopy.

Immobilization of hemoglobin on stable mesoporous multilamellar silica vesicles and their activity and stability

2005 ◽  
Vol 20 (10) ◽  
pp. 2682-2690 ◽  
Author(s):  
Yufang Zhu ◽  
Weihua Shen ◽  
Xiaoping Dong ◽  
Jianlin Shi
Keyword(s):  
Thermal Stability ◽  
Pore Size ◽  
X Ray Diffraction ◽  
X Ray ◽  
Practical Applications ◽  
Silica Material ◽  
Transmission Electron ◽  
Mesoporous Support ◽  
Adsorption Desorption ◽  
Thermal Stability Of

A stable mesoporous multilamellar silica vesicle (MSV) was developed with a gallery pore size of about 14.0 nm. A simulative enzyme, hemoglobin (Hb), was immobilized on this newly developed MSV and a conventional mesoporous silica material SBA-15. The structures and the immobilization of Hb on the mesoporous supports were characterized with x-ray diffraction, transmission electron microscopy, N2 adsorption-desorption isotherms, Fourier transform infrared, ultraviolet-visible spectroscopy, and so forth. MSV is a promising support for immobilizing Hb due to its large pore size and high Hb immobilization capacity (up to 522 mg/g) compared to SBA-15 (236 mg/g). Less than 5% Hb was leached from Hb/MSV at pH 6.0. The activity study indicated that the immobilized Hb retained most peroxidase activity compared to free Hb. Thermal stability of the immobilized Hb was improved by the proctetive environment of MSV and SBA-15. Such an Hb-mesoporous support with high Hb immobilization capacity, high activity, and enhanced thermal stability will be attractive for practical applications.

Investigation of Hydrogen Storage Using Combinatorial Thin Films and IR Imaging

2007 ◽  
Vol 1042 ◽  
Author(s):  
Hiroyuki Oguchi ◽  
Ichiro Takeuchi ◽  
Daniel Josell ◽  
Edwin J Heilweil ◽  
Leonid A Bendersky
Keyword(s):  
Thin Films ◽  
Hydrogen Absorption ◽  
Compositional Variation ◽  
X Ray Diffraction ◽  
Cross Sectional ◽  
Ir Camera ◽  
Deposition Chamber ◽  
X Ray ◽  
Transmission Electron ◽  
Beam Deposition

AbstractThree 100 nm-thick Mgx(TM)1-x (TM = Ni and Ti) composition spread thin films having compositional variation 0.4<x<0.95 and capped with a 5 nm-thick Pd layer were deposited in combinatorial electron-beam (e-beam) deposition chamber. Crystallinity of the films was characterized by scanning x-ray diffraction (XRD) and cross-sectional transmission electron microscopy (TEM). Hydrogen absorption and desorption of the films were monitored with an infrared (IR) camera that could image a full area of the films. The observed changes in IR intensity due to hydrogen absorption/desorption demonstrated sensitivity of the method to the differences in compostion, microstructure and type of TM.

Strontium Hydroxyapatite Synthesis, Characterization and Cell Cytotoxicity

2010 ◽  
Vol 160-162 ◽  
pp. 117-122 ◽  
Author(s):  
Zhi Hong Li ◽  
Ji Min Wu ◽  
Shu Jie Huang ◽  
J. Guan ◽  
Xi Zheng Zhang
Keyword(s):  
Thermal Stability ◽  
Hydrothermal Method ◽  
Bone Repair ◽  
X Ray Diffraction ◽  
X Ray ◽  
Strontium Hydroxyapatite ◽  
Transmission Electron ◽  
20 Nm ◽  
Thermal Stability Of ◽  
Phase Chemical

Strontium hydroxyapatite powders was prepared by the hydrothermal method using Sr(NO3)2 and (NH4)2HPO4 as reagents. Fourier transform infrared spectroscopy, X-ray diffraction, Transmission electron microscope, Energy dispersive X-ray, and Thermogravimetric-differential thermal analysis were employed to investigate the crystalline phase, chemical composition, morphology, and thermal stability of the Strontium hydroxyapatite. And the cytotoxicity of Strontium hydroxyapatite was analyzed through MTT assay. Results showed that Strontium hydroxyapatite prepared by hydrothermal Method has excellent crystal structure, good dispersion, high purity, and rod-like morphology with dimensions 200-500 nm in length and 20 nm in diameter. Meanwhile, the apatite has poor thermal stability. However, the apatite is cytocompatible and may have better biocompatibility, which can serve as strontium source incorporation into calcium phosphate cement and for bone repair.

Synthesis, Characterization and Thermal Analysis of Rod-Shaped Polyaniline-Barium Ferrites Nanocomposites

2010 ◽  
Vol 150-151 ◽  
pp. 386-390
Author(s):  
Yuan Xun Li ◽  
Ying Li Liu ◽  
Huai Wu Zhang ◽  
Wei Wei Ling
Keyword(s):  
Electron Microscopy ◽  
Thermal Stability ◽  
Barium Ferrite ◽  
In Situ Polymerization ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Barium Ferrites ◽  
Thermal Stability Of

The rod-shaped polyaniline (PANI)-barium ferrite nanocomposites were synthesized by in situ polymerization of aniline in the presence of BaFe12O19 nanoparticles with diameters of 60-80 nm. The composites obtained were characterized by infrared spectra (IR), X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The thermal stability and the composition of the composites were investigated by TG-DTG analysis. The results indicate that the thermal stability of the composites is higher than that of the pure PANI which can be attributed to the interactions existed between PANI chains and ferrite particles.

scholarly journals Preparation of Triple-Functionalized Montmorillonite Layers Promoting Thermal Stability of Polystyrene

Nanomaterials ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 2170
Author(s):  
Chengcheng Yu ◽  
Xu Hu ◽  
Shichao Lu ◽  
Yangchuan Ke ◽  
Jianbin Luo
Keyword(s):  
Thermal Stability ◽  
Thermal Characteristics ◽  
Nitrogen Adsorption ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Chemical Grafting ◽  
Adsorption Desorption ◽  
Maximum Mass Loss ◽  
Thermal Stability Of

The objective of this study was to investigate the effect of three different treatments on the morphology, microstructure, and the thermal characteristics of a montmorillonite (Mt) sample, by using hydrochloric acid (HCl), tributyl tetradecyl phosphonium chloride (TTPC) surfactant, and γ-methacryloxypropyltrimethoxysilane (γ-MPS). The resultant nanofillers were characterized by Fourier transform infrared (FTIR), X-ray diffraction (XRD), transmission electron microscopy (TEM), nitrogen adsorption–desorption analysis, X-ray fluorescence spectrometry (XRF), and thermogravimetric analysis (TGA). The results showed that the amount of chemical grafting of the γ-MPS was increased after the acid treatment, whereas the amount of intercalation of the TTPC surfactant was decreased. The preintercalation of TTPC or silylation of γ-MPS, for the Mt sample, had a certain hindrance effect on its subsequent silylation or intercalation treatments. Furthermore, the effect of four different nanofillers on the thermal stability properties of the polystyrene (PS) matrix were also investigated. The results showed an increase in thermal stability for the triple-functionalized Mt, compared with the double-functionalized samples. The onset decomposition temperatures and the maximum mass loss temperatures of the PS nanocomposites were increased by 27 °C and 32 °C, respectively, by the incorporation of triple-modified Mt, as a result of the good exfoliation and dispersion of the nanolayers, more favorable polymer–nanofiller interaction, as well as the formation of a more remarkable tortuous pathway in the continuous matrix.

Microstructure and Thermal Stability of Ultra Fine Grained Mg and Mg-Gd Alloys Prepared by High-Pressure Torsion

2005 ◽  
Vol 482 ◽  
pp. 183-186 ◽  
Author(s):  
Jakub Čížek ◽  
Ivan Procházka ◽  
Bohumil Smola ◽  
Ivana Stulíková ◽  
Radomír Kužel ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Thermal Stability ◽  
High Pressure ◽  
Positron Lifetime ◽  
High Pressure Torsion ◽  
X Ray Diffraction ◽  
X Ray ◽  
Fine Grained ◽  
Transmission Electron ◽  
Thermal Stability Of

Bulk samples of pure Mg and Mg-Gd alloys were prepared by high-pressure torsion (HPT). The HPT made samples exhibit ultra fine grained (UFG) structure with grain size around 100 nm. Results of microstructure investigations of the UFG samples obtained by positron lifetime (PL) spectroscopy, transmission electron microscopy (TEM) and X-ray diffraction (XRD) are presented. In particular, lattice defects introduced by HPT were characterized. The data obtained at atomistic level are compared with macroscopic properties given by microhardness measurements.

Laminated Si3N4/SiC Composites with Self-Sealed Structure

2007 ◽  
Vol 280-283 ◽  
pp. 1873-1876 ◽  
Author(s):  
Zhengbo Yu ◽  
Zoran Krstić ◽  
Vladimir D. Krstić
Keyword(s):  
Layer Thickness ◽  
Fracture Behavior ◽  
Thickness Ratio ◽  
X Ray Diffraction ◽  
Relative Thickness ◽  
X Ray ◽  
Layer Thickness Ratio ◽  
Sic Composites ◽  
Physical And Chemical ◽  
Work Of Fracture

Self-sealed laminar Si3N4/SiC composites, with different cross-section shapes and various thickness ratios of Si3N4 to SiC, have been fabricated. The laminates consist alternately of thicker Si3N4 layers ranging from 100 to 500µm and thinner SiC layers ranging from 6 to 15µm after sintering. Preliminary results indicate that SiC thin layer forms during sintering according to the reaction Si3N4 + 3C ® 3SiC + 2N2, which is confirmed by X-ray diffraction. An excellent physical and chemical compatibility between Si3N4 and SiC layers was observed. The self-sealed Si3N4/SiC composites not only demonstrate a superb resistance to delamination, usually associated with the plate-form ones, but also show a high damage-tolerance behavior. The laminated Si3N4/ SiC composite with a layer thickness ratio of Si3N4 to SiC of approximately 40 gives the highest value of work of fracture (WOF) of approximately 406 kJ/m3, whereas the highest toughness of 21 MPam1/2 was achieved at the layer thickness ratio of 50. The effects of the relative thickness of Si3N4 and SiC layers on the densification of the laminates are examined and fracture behavior and microstructure of the Si3N4/SiC laminates discussed.

scholarly journals Structural Transition in Cu/Fe Multilayered Thin Films

1996 ◽  
Vol 441 ◽  
Author(s):  
Tai D. Nguyen ◽  
Alison Chaiken ◽  
Troy W. Barbee
Keyword(s):  
Layer Thickness ◽  
Ion Beam ◽  
Microstructural Development ◽  
Ion Beam Sputtering ◽  
X Ray Diffraction ◽  
Cross Sectional ◽  
X Ray ◽  
Transmission Electron ◽  
Beam Sputtering ◽  
Bcc Structure

AbstractMicrostructural development of Fe and Cu in Cu/Fe multilayers of layer thickness 1.5–10 nm prepared on Si, Ge, and MgO substrates by ion beam sputtering has been studied using x-ray diffraction and cross-sectional transmission electron microscopy (TEM). High-angle x-ray results show an fcc Cu structure and a distorted bcc structure in the Fe layers at 5 nm-layer-thickness and smaller, and bcc Fe (110) and fcc Cu (111) peaks in the 10 nm-layer-thickness samples. Lowangle x-ray diffraction indicates that the layers in the samples grown on MgO substrates have a more uniform and smooth layered structure than the multilayers grown on Si and Ge substrates, which results from larger grains in the MgO substrate samples for the same layer thickness. Relationships among growth, microstructure, and interfaces with layer thickness are discussed.

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