Microstructure and Kinetics of the Interface Reaction Between Titanium Thin Films and (1<ovl>1</ovl>2) Sapphire Substrates

AbstractWe studied the reactivity of titanium with the R-plane (112) surface of sapphire by transmission electron microscopy (TEM), x-ray diffraction (XRD), and Rutherford backscattering (RBS) techniques. Cross-section TEM specimens were prepared from 200–400 nm thick titanium films deposited on sapphire at 25, 525, 554, 562, 580, 630, and 663°C to observe the interfacial region. In samples deposited at 25°C, without further annealing, no reaction zone could be seen in the TEM. In all other samples titanium reduced the sapphire to form Ti0 6 7[O0 3 3] and Ti3Al[O], Ti and Ti3Al with oxygen in solid solution. An activation energy of 24.7 ± 6 kcal/deg-mole was determined for the growth of the Ti3Al[O] layer. Layer thickness measurements from the TEM and RBS studies were within 10–20% of one another.</jats:p

Determination of interface width using EELS fine structure changes

The concept of interfacial width is often invoked in many materials science phenomena which relate to the structure and properties of internal interfaces. The numerical value of interface width is an important input parameter in diffusion equations, sintering theories as well as in many electronic devices/processes. Most often, however, this value is guessed rather than determined or even estimated. In this paper we present a method of determining the effective structural and electronic- structural width of interphase interfaces using low- and core loss fine structure effects in EELS spectra.The specimens used in the study were directionally solidified eutectics (DSEs) in the system; NiO-ZrO2(CaO), NiO-Y2O3 and MnO-ZrO2(ss). EELS experiments were carried out using a VG HB-501 FE STEM and a Hitachi HF-2000 FE TEM.</jats:p

Plan-View CBED Studies of Nio-Zro₂(CaO) Interfaces

ABSTRACTLow energy lamellar interfaces in the directionally solidified eutectic (DSE) NiO-ZrO2(CaO) have been investigated using transmission electron diffraction and imaging. The symmetry of this bicrystal and an aspect of interfacial relaxations in the form of symmetry lowering in-plane rigid body translation (RBT) have been explored by performing convergent beam electron diffraction (CBED) experiments of plan-view bicrystals. Edge-on interfaces have also been studied by conventional and high resolution transmission electron microscopy (CTEM and HRTEM respectively), and electron diffraction fine structure analysis. Despite certain experimental difficulties due to interfacial defects and strain, plan-view CBED patterns offered valuable information concerning bicrystal symmetry and indicated no symmetry lowering RBT in this bicrystal. The suitability of plan-view CBED is briefly discussed in view of its potential as a technique to determine bicrystal symmetry and RBT.</jats:p

Plan-view TEM of planar interfaces

Transmission electron microscopy (TEM), incorporating imaging, diffraction and spectrometry has contributed significantly to the understanding of the structure of crystalline interfaces. Traditionally, planar interfaces are investigated using cross-sectional views (electron beam parallel to the interface) of the specimen. However, plan-view TEM (PVTEM) has recently emerged as a viable and supplementary technique to cross-sectional TEM (XTEM). PVTEM enjoys certain definite advantages over XTEM. One important consideration is that the interface in a PV specimen is buried (sandwiched between two crystals) and is expected to be free of artefacts induced by specimen preparation procedures. Moreover, many multilayer electronic materials are amenable to PVTEM because they can be easily backthinned to electron transparency with virtually no damage to the internal interfaces. PV specimens clearly contain much larger interface area than XTEM specimens, which may be of great significance when statistics are considered. Apart from these considerations PVTEM studies can also offer specific information about the interface not always possible in XTEM. In this brief communication we report some of our results on imaging, diffraction and spectrometry of interfaces obtained by viewing the interfaces in the PV mode.</jats:p

INTERFACIAL DEFECTS IN NiO-ZrO2 (CaO) EUTECTIC

Des interfaces lamellaires dans l'eutectique obtenu par solidification dirigée (ESD) NiO-ZrO2(CaO) ont été étudiées par des techniques optiques électroniques. Plusieurs défauts caracteristiques à l'interface ont été analysés et interprétés à l'aide de considérations géometriques. Une attention particulière est portée aux défauts topographiques et à leurs caracteristiques structurales et fonctionnelles.Lamellar interfaces in the NiO-ZrO2(CaO) directionally solidified eutectic (DSE) have been investigated using electron optical techniques. Several characteristic interfacial defects have been analyzed and discussed invoking geometric arguments. Special attention is given to the topographical defects and their structural and functional characteristics

Sreels Analysis of Oxygen-Rich Inversion Domain Boundaries in Aluminum Nitride

AbstractSpatially resolved electron energy loss spectroscopy analysis has been conducted on planar inversion domain boundaries in aluminum nitride. The defects were found to contain 1.5 monolayers of oxygen, in agreement with the most recent structural model of Westwood. From variations in near-edge structure, the local atomic environments of both oxygen and aluminum are compared with α-A1203, γ-A1203 and γ-AION standards. Based upon this study the stnrcture of the inversion domain boundary is found to resemble that of the cubic γ-AION spinel, and eliminates from consideration those structural models based upon ai-Al203. Furthermore, quantification of the shape resonances provided Al-O bond-length data from the inversion domain boundary interface. These distances closely agree with the Youngman Model that has recently been further refined by Westwood et al.</jats:p