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Showing 1 to 20 of 33 for “"amorphous solids"”.
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Low-temperature thermal expansion of amorphous solids
"For most amorphous materials at temperatures below ~ 1 K, the magnitudes and temperature dependences of specific heat, thermal conductivity and ultrasonic dispersion are qualitatively similar, independent of chemical composition. It has been suggested that thermal expansion also exhibits this …
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Modelling of defect states in covalent amorphous solids
… the bulk and defect structures, in hydrogenated amorphous silicon. Emphasis is given to the systematic analysis of the changes in the network structures, which occur due to the incorporation of hydrogen, at different levels of concentration. The atomic-level stress in the simulated structures is …
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Universal sound attenuation in amorphous solids at low-temperatures
"Disordered solids are known to exhibit quantitative universalities at low temperatures, the most striking of which is the ultrasonic attenuation coefficient 1/Q(ω). The established theory of tunneling two state systems (TTLS) in its original form (i.e. without extra fitting functions and …
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The structure and excitations of amorphous solids and surfaces
Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Physics, 1979.
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THE YIELDING TRANSITION IN SOFT AMORPHOUS SOLIDS UNDER OSCILLATORY SHEAR: FROM MICROSCOPIC REARRANGEMENTS TO MACROSCOPIC FAILURE
… a wide class of soft materials that respond like solids to small stresses but exhibit fluid-like behavior when the applied stress exceeds a certain threshold value (the yield stress). Beyond its major relevance in various applications from the cosmetic to the food industry, the yielding transition …
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Electronic Structure of Three Center Two Electron Bonds in Boron Rich Materials: A Study of Molecules, Crystals, and Amorphous Solids using the ab initio Orthogonalized Linear Combination of Atomic Orbitals Method
… bonding structures with their neighbors in solids, and/or for molecular boron the icosahedra tends to incorporate substitutional carbon atoms. The resultant bonding structures are often of a 3 center 2 electron nature. The visualization of these 3 center 2 electron bonds varies in the …
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Connecting Small-Angle Diffraction With Real-Space Images by Quantitative TEM of Amorphous Thin Films
"Amorphous solids are a technologically important class of materials whose structure is not yet well-described. High resolution structural probes such as neutron or x-ray scattering give limited information, restricted mainly to near-neighbor bond lengths and bond angles, but these probes become …
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Connecting small-angle diffraction with real-space images by quantitative TEM of amorphous thin-films
"Amorphous solids are a technologically important class of materials whose structure is not yet well-described. High resolution structural probes such as neutron or x-ray scattering give limited information, restricted mainly to near-neighbor bond lengths and bond angles, but these probes become …
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Temporal properties of avalanche dynamics
Slip avalanches occur in both crystalline and amorphous solids. Slip avalanches and avalanches in other systems are thought to be critical phenomena linked to a nonequilibrium phase transition. In this thesis we explore some temporal properties of experimental slip avalanche dynamics. These …
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Universal properties of low-temperature glass
Amorphous solids (glasses) present universal properties strikingly different from that of crystalline counterparts at low temperatures, regardless of their microscopic nature. Tunneling-two-level-system model (TTLS model) successfully explained several universalities below 1K, but it cannot explain …
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Transport Characteristics of Amorphous Semiconductors in the Dilute Carrier Regime: A Variable Range Hopping Treatment
… which are used to find the conductivity of amorphous solids as a function of temperature, specifically the work done by N. F. Mott and Apsley et al. and we point out the problems with deriving such a relationship. We then develop a self consistent numerical system for calculating the charge …
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Study of tunneling impurities in alkali halides at low temperatures
… (with r ~ +1) is similar to that of many amorphous solids.
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Dynamical perspective of stability in glasses
… routes govern the energy landscape of amorphous solids.
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Design, Synthesis, Characterization, and Evaluation of Boronate Ester-Linked Porous Materials: Covalent Organic Frameworks and Polymers of Intrinsic Microporosity
… <p>The newest materials produced are porous yet amorphous and are the first family of boronate ester-linked polymers of intrinsic microporosity (PIMs). This family utilized the kink in a spirobisindane bis-diol monomer along with linear and trigonal boronic acids to produce amorphous solids which …
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A Quantitative Study of Drug Recrystallization in Drug-In-Adhesive Transdermal Patches Using Vibrational Spectroscopy
… frequently present in metastable forms, such as amorphous solids or supercooled liquids. These drug states are thermodynamically unstable and tend to undergo recrystallization. Recrystallization of the active pharmaceutical ingredient can adversely affect the efficacy of transdermal products. …
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Structure of valinomycin-K+ complex and cryptate-k+ complex in solution by extended x-ray absorption fine structure
… atoms. Since EXAFS can be used for crystals, amorphous solids, solutions and gases it has a strong advantage over x-ray crystallography in many cases for determining local structural information. I used EXAFS to determine what structural changes occur between the known crystalline states and …
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Constitutive equations and failure criteria for amorphous polymeric solids
… for the elastic-viscoplastic deformation of amorphous solids. Their theory is motivated by and builds on the work of Parks, Argon, Boyce, Arruda, and their co-workers (e.g. Boyce et al., 1988; Arruda & Boyce, 1993) on modeling the plastic deformation of amorphous polymers. The theory of Anand …
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(e,2e) spectroscopic investigations of the spectral momentum densities of thin carbon films
… the electronic structure of both crystalline and amorphous solids. The three fundamental quantities, the band structure, electron density of states, and electron momentum distribution can be simultaneously derived from the measured (e,2e) cross section. A review of single electron and (e,2e) …
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Adapting a Cryogen-Free Measurement System for Geological Materials: Method Development for Thermal Conductivity Measurements Below 300 K with Applications to Planetary Science
… temperature, consistent with the behaviour of amorphous solids. Meteorites exhibit more complex behaviour. Despite being composed mainly of crystalline materials, phonon transport is suppressed by porosity and grain boundaries, resulting in thermal conductivity trends similar to disordered …
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Non-affine lattice dynamics of disordered solids
… and vibrational properties of disordered and amorphous solids. Resorting to the theoretical framework of non-affine lattice dynamics the attention is focused on the analysis of disordered networks and lattices which serve as tractable model systems for real materials. Firstly, we discuss the …
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