Download or read book Crystalline to Amorphous Transformation in Silicon written by Suryanarayana Murty Cheruvu and published by . This book was released on 1982 with total page 190 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Crystalline amorphous Transformation of Precipitates in Zircaloy Under Electron Irradiation written by Arthur Moses Thompson Motta and published by . This book was released on 1988 with total page 170 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Crystalline to Amorphous Transformation in Silicon written by and published by . This book was released on 1982 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: In the present investigation, an attempt was made to understand the fundamental mechanism of crystalline-to-amorphous transformation in arsenic implanted silicon using high resolution electron microscopy. A comparison of the gradual disappearance of simulated lattice fringes with increasing Frenkel pair concentration with the experimental observation of sharp interfaces between crystalline and amorphous regions was carried out leading to the conclusion that when the defect concentration reaches a critical value, the crystal does relax to an amorphous state. Optical diffraction experiments using atomic models also supported this hypothesis. Both crystalline and amorphous zones were found to co-exist with sharp interfaces at the atomic level. Growth of the amorphous fraction depends on the temperature, dose rate and the mass of the implanted ion. Preliminary results of high energy electron irradiation experiments at 1.2 MeV also suggested that clustering of point defects occurs near room temperature. An observation in a high resolution image of a small amorphous zone centered at the core of a dislocation is presented as evidence that the nucleation of an amorphous phase is heterogeneous in nature involving clustering or segregation of point defects near existing defects.
Download or read book Spontaneous Crystalline to amorphous Phase Transformation of Organic Or Medicinal Compounds in the Presence of Porous Media written by Ken Kangyi Qian and published by . This book was released on 2011 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Phase Transformations in Crystalline and Amorphous Alloys written by Barry L. Mordike and published by I R Publications, Limited. This book was released on 1983 with total page 274 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Crystalline to Amorphous Transformation in Ion Irradiated Al3Ni written by Anthony Joseph Carbone and published by . This book was released on 1996 with total page 298 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Crystalline to amorphous Transformation in Irradiated Quartz written by Marina Rose Pascucci and published by . This book was released on 1980 with total page 190 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Crystalline to amorphous transformation of intermetallic compounds in the zr fe m system induced by irradiation written by A. T. Motta and published by . This book was released on 1995 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Crystal amorphous Transformation Pathway Via Defect Templating in Phase change Materials written by Pavan Nukala and published by . This book was released on 2015 with total page 326 pages. Available in PDF, EPUB and Kindle. Book excerpt: Phase-change materials (PCM) such as GeTe and Ge-Sb-Te alloys are potential candidates for non-volatile memory applications, because they can reversibly and rapidly transform between a crystalline phase and an amorphous phase with medium-range order. Traditionally, crystal-amorphous transformation in these materials has been carried out via melt-quench pathway, where the crystalline phase is heated beyond its melting point by the rising edge of an electric pulse, and the melt phase is quenched by the falling edge into a glassy phase. Formation of an intermediate melt phase in this transformation pathway requires usage of large switching current densities, resulting in energy wastage, and device degradation issues. Furthermore, melt-quench pathway is a brute force strategy of amorphizing PCM, and does not utilize the peculiar structural properties in crystalline phase. It will be beneficial from a device perspective that crystal-amorphous transformation is carried out via subtler solid-state pathways.
Download or read book Amorphous Metallic Alloys written by F. E. Luborsky and published by Butterworth-Heinemann. This book was released on 1983 with total page 556 pages. Available in PDF, EPUB and Kindle. Book excerpt: Index of amorphous alloys
Download or read book Radiation induced Transformation of Amorphous to Crystalline Solids written by Carl Matthew Cox and published by . This book was released on 1967 with total page 448 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Reaction of Hydrogen with Crystalline and Amorphous Alloys written by Xian-Li Yeh and published by . This book was released on 1987 with total page 224 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book A Study of the Amorphous to Crystalline Transformation of Some Metallic Glasses written by Bouhas Benbahi and published by . This book was released on 1988 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Fundamental Mechanisms Driving the Amorphous to Crystalline Phase Transformation written by and published by . This book was released on 2011 with total page 17 pages. Available in PDF, EPUB and Kindle. Book excerpt: Phase transformations are ubiquitous, fundamental phenomena that lie at the heart of many structural, optical and electronic properties in condensed matter physics and materials science. Many transformations, especially those occurring under extreme conditions such as rapid changes in the thermodynamic state, are controlled by poorly understood processes involving the nucleation and quenching of metastable phases. Typically these processes occur on time and length scales invisible to most experimental techniques (?s and faster, nm and smaller), so our understanding of the dynamics tends to be very limited and indirect, often relying on simulations combined with experimental study of the ''time infinity'' end state. Experimental techniques that can directly probe phase transformations on their proper time and length scales are therefore key to providing fundamental insights into the whole area of transformation physics and materials science. LLNL possesses a unique dynamic transmission electron microscope (DTEM) capable of taking images and diffraction patterns of laser-driven material processes with resolution measured in nanometers and nanoseconds. The DTEM has previously used time-resolved diffraction patterns to quantitatively study phase transformations that are orders of magnitude too fast for conventional in situ TEM. More recently the microscope has demonstrated the ability to directly image a reaction front moving at H"3 nm/ns and the nucleation of a new phase behind that front. Certain compound semiconductor phase change materials, such as Ge2Sb2Te5 (GST), Sb2Te and GeSb, exhibit a technologically important series of transformations on scales that fall neatly into the performance specifications of the DTEM. If a small portion of such material is heated above its melting point and then rapidly cooled, it quenches into an amorphous state. Heating again with a less intense pulse leads to recrystallization into a vacancy-stabilized metastable rock salt structure. Each transformation takes H"0-100 ns, and the cycle can be driven repeatedly a very large number of times with a nanosecond laser such as the DTEM's sample drive laser. These materials are widely used in optical storage devices such as rewritable CDs and DVDs, and they are also applied in a novel solid state memory technology - phase change memory (PCM). PCM has the potential to produce nonvolatile memory systems with high speed, extreme density, and very low power requirements. For PCM applications several materials properties are of great importance: the resistivities of both phases, the crystallization temperature, the melting point, the crystallization speed, reversibility (number of phase-transformation cycles without degradation) and stability against crystallization at elevated temperature. For a viable technology, all these properties need to have good scaling behavior, as dimensions of the memory cells will shrink with every generation. In this LDRD project, we used the unique single-shot nanosecond in situ experimentation capabilities of the DTEM to watch these transformations in GST on the time and length scales most relevant for device applications. Interpretation of the results was performed in conjunction with atomistic and finite-element computations. Samples were provided by collaborators at IBM and Stanford University. We observed, and measured the kinetics of, the amorphous-crystalline and melting-solidification transitions in uniform thin-film samples. Above a certain threshold, the crystal nucleation rate was found to be enormously high (with many nuclei appearing per cubic?m even after nanosecond-scale incubation times), in agreement with atomistic simulation and consistent with an extremely low nucleation barrier. We developed data reduction techniques based on principal component analysis (PCA), revealing the complex, multi-dimensional evolution of the material while suppressing noise and irrelevant information. Using a novel specimen geometry, we also achieved repeated switching between the amorphous and crystalline phases enabling in situ study of structural change after phase cycling, which is relevant to device performance. We also observed the coupling between the phase transformations and the evolution of morphology on the nanometer scale, revealing the gradual development of striations in uniform films and preferential melting at sharp edges in laser-heated nanopatterned GST. This nonuniform melting, interpreted through simulation as being a direct result of geometrical laser absorption effects, appears to be responsible for a marked loss in morphological stability even at moderate laser intensities and may be an important factor in the longevity of nanostructured phase change materials in memory applications.
Download or read book Amorphous and Nanocrystalline Materials written by A. Inoue and published by Springer Science & Business Media. This book was released on 2013-04-17 with total page 216 pages. Available in PDF, EPUB and Kindle. Book excerpt: Amorphous and nanocrystalline materials are a class of their own. Their properties are quite different to those of the corresponding crystalline materials. This book gives systematic insight into their physical properties, structure, behaviour, and design for special advanced applications.
Download or read book A NEW TECHNIQUE FOR OBSERVING THE AMORPHOUS TO CRYSTALLINE TRANSFORMATION IN THIN SURFACE LAYERS ON SILICON WAFERS written by and published by . This book was released on 1980 with total page 20 pages. Available in PDF, EPUB and Kindle. Book excerpt: Thin amorphous ([alpha]) films of silicon created by ion-implantation have been studied in-situ while undergoing the amorphous to crystalline transformation in the electron microscope. The specimens were prepared in such a manner that the amorphous/crystalline interface was viewed edge-on and its advance during annealing was easily observed over distances of several microns. Growth rates and activation energies were measured. The active role that defects play during the regrowth process was also studied. An additional advantage of the technique was that in a single specimen different segments of the recrystallization front advanced along several different growth directions simultaneously, hence the effect of regrowth direction on the interface migration rate and defect formation was graphically displayed in a single specimen.
Download or read book The Kinetics of Amorphous crystalline Transformations written by A. Papp and published by . This book was released on 1974 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
