Interface structures in polycrystalline ceramic materials

1986 ◽  
Vol 44 ◽  
pp. 468-471
Author(s):  
K. J. Morrissey
Keyword(s):  
Electron Microscopy ◽  
Analytical Electron Microscopy ◽  
Physical And Mechanical Properties ◽  
High Resolution Electron Microscopy ◽  
Ceramic Materials ◽  
Polycrystalline Materials ◽  
Transmission Electron ◽  
Resolution Electron ◽  
Interface Structures

Grain boundaries and interfaces play an important role in determining both physical and mechanical properties of polycrystalline materials. To understand how the structure of interfaces can be controlled to optimize properties, it is necessary to understand and be able to predict their crystal chemistry. Transmission electron microscopy (TEM), analytical electron microscopy (AEM,), and high resolution electron microscopy (HREM) are essential tools for the characterization of the different types of interfaces which exist in ceramic systems. The purpose of this paper is to illustrate some specific areas in which understanding interface structure is important. Interfaces in sintered bodies, materials produced through phase transformation and electronic packaging are discussed.

Structure, Composition and Stability of Heterophase Boundaries

1997 ◽  
Vol 3 (S2) ◽  
pp. 673-674
Author(s):  
M. Rühle ◽  
T. Wagner ◽  
S. Bernath ◽  
J. Plitzko ◽  
C. Scheu ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Elevated Temperatures ◽  
Analytical Electron Microscopy ◽  
High Resolution Electron Microscopy ◽  
Advanced Materials ◽  
Bulk Crystals ◽  
Transmission Electron ◽  
Resolution Electron ◽  
The Stability

Heterophase boundaries play an important role in advanced materials since those materials often comprise different components. The properties of the materials depend strongly on the properties of the interface between the components. Thus, it is important to investigate the stability of the microstructure with respect to annealing at elevated temperatures. In this paper results will be presented on the structure and composition of the interfaces between Cu and (α -Al2O3. The interfaces were processed either by growing a thin Cu overlayer on α- Al2O3 in a molecular beam epitaxy (MBE) system or by diffusion bonding bulk crystals of the two constituents in an UHV chamber. To improve the adhesion of Cu to α -Al2O3 ultrathin Ti interlayers were deposited between Cu and α - Al2O3.Interfaces were characterized by different transmission electron microscopy (TEM) techniques. Quantitative high-resolution electron microscopy (QHRTEM) allows the determination of the structure (coordinates of atoms) while analytical electron microscopy (AEM) allows the determination of the composition with high spatial resolution.

AlN Nanorods synthesized by a Mechanothermal Process

2011 ◽  
Vol 1288 ◽  
Author(s):  
G. Rosas ◽  
J. Chihuaque ◽  
C. Patiño-Carachure ◽  
R. Esparza ◽  
R. Pérez
Keyword(s):  
Electron Microscopy ◽  
Mechanical Milling ◽  
Annealing Treatment ◽  
High Resolution Electron Microscopy ◽  
Dynamical Theory ◽  
Transmission Electron ◽  
Resolution Electron ◽  
Structural Configurations ◽  
Simulated Images

ABSTRACTWell-crystallized AlN nanorods have been produced by mechanical milling and subsequent annealing treatment of the milling powders (mechanothermal process). High purity AlN powders were used as the starting material. Mechanical milling was carried out in a vibratory SPEX mill for 30 h, using vials and balls of silicon nitride. The annealing treatment was carried out at 1200 ºC for 10 min. The characterization of the samples was performed by X-ray diffractometry and transmission electron microscopy (TEM). TEM observations indicated that the synthesized nanorods consisted of 30 nm in diameter and 100 nm in length. High resolution electron microscopy observations have been used in the structural characterization. AlN nanorods exhibit a well-crystallized structure. The growing direction of the nanorods is close to the [001] direction. The structural configurations have been explored through comparisons between experimental HREM images and theoretically simulated images obtained with the multislice method of the dynamical theory of electron diffraction.

Characterization of interface structures in nanocrystalline germanium by means of high-resolution electron microscopy and molecular dynamics simulations

1996 ◽  
Vol 211 (3) ◽  
Author(s):  
W. Neumann ◽  
H. Hofmeister ◽  
D. Conrad ◽  
K. Scheerschmidt ◽  
S. Ruvimov
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Vapor Deposition ◽  
High Resolution Electron Microscopy ◽  
Amorphous Thin Films ◽  
Resolution Electron ◽  
Nanocrystalline Particles ◽  
Dynamics Simulations ◽  
Interface Structures

AbstractThe atomic structure of nanocrystalline particles formed by vapor deposition and subsequent annealing of amorphous thin films of germanium was studied by high resolution electron microscopy (HREM). The HREM images revealed a strongly varied multiply twinned structure. In some regions of adjacent twins contrast features were detected which were caused by an overlapping of twin lamellae. It will be shown by HREM contrast simulations that these interface types can be described by Σ = 3

Microstructure and Lattice Defects in Polycrystalline Nuclear Ceramics

1968 ◽  
Vol 26 ◽  
pp. 270-271
Author(s):  
J. L. Daniel ◽  
S. J. Mayhan
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Resolution Electron Microscopy ◽  
Ceramic Materials ◽  
Thin Sections ◽  
Small Areas ◽  
Physical Measurements ◽  
Transmission Electron ◽  
Resolution Electron ◽  
Mechanical Thinning

Transmission electron microscopy of several nuclear ceramics has been extended to thin sections of as - fabricated poly-crystalline materials, by use of a thinning technique utilizing only common metallographic practices. The method is based on work by Doherty and Leombruno. However, while mechanical thinning (polishing) produces large, evenly thinned specimens, the surface of ceramic materials retains many shallow scratches and defects introduced by the polishing medium. On the other hand, the chemical thinning methods commonly applied produce only very small areas which are thin enough for examination by transmission electron microscopy, since preferential attack occurs on grain boundaries, inclusions, second phases, etc. By combining the chemical polish with the mechanical thinning procedures, large, relatively clean areas of ceramic materials can be produced. Another significant advantage is that in the course of thinning, the same specimens can be examined frequently and in detail by light microscopy, some physical measurements can be made along the way (e.g., microhardness, spectral transmission, autoradiography), and all observations can be closely correlated finally with the high resolution electron microscopy.

High-Resolution Transmission Electron Microscopy Study of WC-Co Alloy doped with other Metal Carbides; VC, Cr3C2, and ZrC

2007 ◽  
Vol 558-559 ◽  
pp. 993-996 ◽  
Author(s):  
Y. Yamanaka ◽  
T. Taniuchi ◽  
F. Shirase ◽  
T. Tanase ◽  
Yuichi Ikuhara ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
High Resolution Electron Microscopy ◽  
Microscopy Study ◽  
Electron Microscopy Study ◽  
Metal Carbides ◽  
Transmission Electron ◽  
Resolution Electron ◽  
Interface Structures ◽  
Co Alloys

The WC/Co interface structures in WC-Co alloys doped with VC, Cr3C2 or ZrC were examined by high-resolution electron microscopy (HRTEM) and X-ray energy dispersive spectroscopy (EDS) with a special interest in the segregation behavior of respective dopants at the WC/Co interfaces. It was confirmed that the addition of VC or Cr3C2 were effective to reduce WC grain size while that of ZrC was not. In case of VC or Cr3C2-doped alloys, the morphology of WC grains largely changed comparing with undoped and ZrC-doped alloys. The WC/Co interfaces of the two alloys tend to form micro facets with (0001) and {1010} habits. EDS analysis with a sub-nano scale probe revealed that the dopants strongly segregated at the two habits. In contrast, such morphology change, and also dopant segregation, could not be observed in ZrC-doped alloy. In our study, doped ZrC was not found to solute in Co-phase. Doped ZrC distributed in Co-phase to form other grains mainly consisting of ZrC. The interface structures of WC/Co could be considered to be closely related to the inhibition effect to WC grain growth.

Structural Characterization Of Laser Lift-Off GaN

2000 ◽  
Vol 617 ◽  
Author(s):  
Eric A. Stach ◽  
M. Kelsch ◽  
W.S. Wong ◽  
E.C. Nelson ◽  
T. Sands ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Chemical Characterization ◽  
High Resolution Electron Microscopy ◽  
Economic Benefits ◽  
Thin Layers ◽  
Transmission Electron ◽  
Resolution Electron ◽  
Lift Off ◽  
Microscopy Techniques

AbstractLaser lift-off and bonding has been demonstrated as a viable route for the integration of III-nitride opto-electronics with mainstream device technology. A critical remaining question is the structural and chemical quality of the layers following lift-off. In this paper, we present detailed structural and chemical characterization of both the epitaxial layer and the substrate using standard transmission electron microscopy techniques. Conventional diffraction contrast and high resolution electron microscopy indicate that the structural alteration of the material is limited to approximately the first 50 nm. Energy dispersive electron spectroscopy line profiles show that intermixing is also confined to similar thicknesses. These results indicate that laser lift-off of even thin layers is likely to result in materials suitable for device integration. Additionally, because the damage to the sapphire substrate is minimal, it should be possible to polish and re-use these substrates for subsequent heteroepitaxial growths, resulting in significant economic benefits.

Characterization of ErAs/GaAs and GaAs/ErAs/GaAs Structures

1989 ◽  
Vol 160 ◽  
Author(s):  
Jane G. Zhu ◽  
Chris J. Palmstrøm ◽  
Suzanne Mounier ◽  
C. Barry Carter
Keyword(s):  
Electron Microscopy ◽  
High Resolution Electron Microscopy ◽  
Gaas Layer ◽  
Misfit Dislocations ◽  
Weak Beam ◽  
Transmission Electron ◽  
Resolution Electron ◽  
Small Grains ◽  
Major Defect

AbstractA series of ErAs/GaAs and GaAs/ErAs/GaAs epilayers have been grown on (100) GaAs substrates by molecular-beam epitaxy. Misfit dislocations at the ErAs/GaAs interface have been analyzed using the weak-beam technique of transmission electron microscopy. The microstructure of GaAs/ErAs/GaAs layers have been characterized using conventional and high-resolution electron microscopy. Twinning inside the upper GaAs layer is the major defect. Although the desired epitactic (100) GaAs on (100) ErAs does dominate, small grains of GaAs with (111) or {122} orientations have been observed at the GaAs/ErAs heterojunction.

Synthesis and characterization of antimony oxide nanoparticles

2001 ◽  
Vol 16 (3) ◽  
pp. 803-805 ◽  
Author(s):  
Zaoli Zhang ◽  
Lin Guo ◽  
Wendong Wang
Keyword(s):  
Electron Microscopy ◽  
Water Solution ◽  
High Resolution Electron Microscopy ◽  
Antimony Oxide ◽  
Oxide Nanoparticles ◽  
Internal Standards ◽  
Transmission Electron ◽  
Initial Stage ◽  
Resolution Electron

Antimony oxide nanoparticles were synthesized in the presence of the polyvinyl alcohol in water solution through the reaction between SbCl3 and NaOH. The size of the particle ranges from 10 to 80 nm, and the largest one can even reach 200 nm, which may begin to grow in the initial stage of the reflux. Transmission electron microscopy and high-resolution electron microscopy (HREM) were used to characterize the microstructure of these nanoparticles. Using silicon single crystals as internal standards, the polycrystalline diffraction pattern analysis shows only presence of cubic Sb2O3 phase. The bright-field micrograph displays that the particles may have various polyhedral configurations. HREM results show that the particles are crystallographically perfect. Moreover, the formation mechanism of nanoparticles is discussed.

Tem Structure Characterization Of Ti/Al and Ti/Al/Ni/Au Ohmic Contacts For n-GaN

1996 ◽  
Vol 423 ◽  
Author(s):  
S. Ruvimov ◽  
Z. Liliental-Weber ◽  
J. Washburn ◽  
K. J. Duxstad ◽  
E. E. Hailer ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Resolution ◽  
Ohmic Contacts ◽  
High Resolution Electron Microscopy ◽  
Structure Characterization ◽  
Transmission Electron ◽  
Resolution Electron ◽  
Thin Polycrystalline

AbstractTransmission electron microscopy has been applied to characterize the structure of Ti/Al and Ti/Al/Ni/Au ohmic contacts on n-type GaN (˜1017 cm−3 ) epitaxial layers. A thin polycrystalline cubic TiN layer epitaxially matched to the (0001) GaN surface was detected at the interface with the GaN substrate. This layer was studied in detail by electron diffraction and high resolution electron microscopy. The orientation relationship between the cubic TiN and the GaN was found to be: {111}TiN//{00.1}GaN, [110]TiN//[11.0]GaN, [112 ]TiN//[ 10.0]GaN. The formation of this cubic TiN layer results in an excess of N vacancies in the GaN close to the interface which is considered to be the reason for the low resistance of the contact.

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