Scanning Tunneling Microscope (STM):
Device for studying the surface topography of solid electronic conductors with a lateral resolution better than the atomic size. In STM, a sharp microscope tip is scanned over the specimen surface without touching it, and at the same time, the tunneling current between the tip and the surface atoms, proportional to the distance between them, is recorded. The results obtained are transformed into the images displaying the atomic structure of a clean surface or the adatom
arrangement.
Scanning Tunneling Microscopy And Its Applications (PG:1)
C. BAI
Cottrell Atmosphere:
Segregation of interstitial solutes at edge dislocations accompanied by a decrease of the overall elastic strain energy due to the fact that the lattice distortions associated with the solute atoms are partially compensated by the lattice distortions associated with the dislocations. Cottrell atmosphere is called condensed if the solute atoms form a continuous string along the dislocation line. The solute concentration necessary to produce condensed atmospheres at all the dislocations is∼10^-4 at% at the dislocation density ∼10^10 cm–2.
Materials of Science (PG: 43)
Vladimir Novikov
Annealing Texture:
Preferred orientation evolved in the course of primary recrystallization or grain growth. Recrystallization texture occurs because recrystallization nuclei are of nonrandom orientations and grow into the deformed matrix at different rates. It can be similar to deformation texture or quite different from it. Texture changes during grain growth are connected with different driving forces for growth of variously oriented grains and different mobility of their boundaries (see compromise texture). Grain growth commonly (but not always) results in weakening of the primary recrystallization texture. Annealing texture is usually characterized by an increased scatter and a decreased intensity in comparison to the initial deformation texture, except for a cube texture in some cold-rolled FCC alloys and the Goss texture in ferritic steels.
Recrystallization, Grain, Growth And Textures (PG:448 )
AMERICAN SOCIETY FOR METALS
Photo-Electron Emission Microscope (PEEM):
Device for studying chemistry, grain orientation, and microstructure of flat, massive specimens using electrons emitted from the specimen’s surface under the influence of a focused beam of high-intensity ultraviolet light (penetration depth ∼10 nm). The lateral resolution of PEEM is ∼15 nm. Heating attachment to PEEM makes it suitable for inþsitu observations.
The photoelectron emission microscope (PEEM) is a microscope type that uses photons for illumination; it is a direct or “paralel” imaging technique ant it uses a so-called cathode lens as part of the microscope objective lens.
Photoelectron emission microscope is a high-contrast method that iis now being rediscovered by surface and materials scientists because of its versatility and surface sensitivity. A summary of its progress from 1930 to the present in electron microscope instrument development would usually be given in terms of tthe image resolution that has been achieved with the lastest instrument. The race started with optical microscopy, and the need for electron microscopists to justify their more copmlex instrument with better resolution than the very advanced and sophisticated optical instrument of their day. The much younger field of surface science has advanced through halfway in PEEM.
IN STIU REAL-TIME CHARACTERIZATION OF THIN FILMS (PG:227)
ORLANDO AUCIELLO
ALAN R. KRAUSS
Metastable Phase
Phase not associated with the absolute minimum of free energy of a thermodynamic system. Metastable phase occurs, providedthe atomic mobility is restricted (as, e.g., martensite, cementite) and the thermodynamic barrier necessary for its nucleation is low in comparison to the stable phase (as, e.g., cementite in cast irons; see graphitization), or due to short diffusion paths necessary for its nucleation and growth (as, e.g., in massive transformation). A nontransformed phase below its equilibrium temperature can also be considered metastable if its transformation into more stable phases does not start yet, or if the commencement of the transformation is kinetically constrained.
A textbook of engineering materials and metallurgy (Pg: 120)
Dr. J.T. Winowlin Jappes
A. Alavudeen
N. Venkateshwaran
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