Adama Tandia

Adama Tandia
Corning Incorporated | Corning · Modeling & Simulation

Ph.D

About

37
Publications
6,338
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833
Citations
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November 2000 - present
Corning Incorporated
Description
  • Materials Design; Process Optimization; Machine Learning; Data Mining

Publications

Publications (37)
Article
Thermal poling is a process by which network modifiers are depleted from the surfaces of oxide glasses through the application of an electric field at moderate temperatures. Several kinetic and thermodynamic questions regarding the glass structure within the depleted layers as well as the process by which they are created remain unanswered. In this...
Article
Brittle oxide glasses can easily break into fragments because of crack branching during fracture. The fundamental mechanism underlying this common phenomenon remains controversial. In this study, using atomic-scale simulations with three independent force fields, we directly observe crack branching in silica glass. The critical speed at which the c...
Article
We conduct systematic studies to investigate the impact of pressure on structure and properties of Na2O‐Al2O3‐SiO2 glass system using molecular dynamics simulations. Glass compositions range from peralkaline, to charge‐balancing, to peraluminous. Hot‐compression operation is applied to as‐prepared glasses with pressure up to 4 GPa. Several key lear...
Article
The theoretically-derived Makishima-Mackenzie (MM) model expresses the Young's modulus of glass in terms of two determining factors, namely, the inter-atomic bonding strength (dissociation energy) and the ways in which atoms are packed (atomic packing fraction). This simple model offers a clear physical picture to understand the compositional depen...
Article
Silicate glasses have no long range order and a short range order similar to their crystalline counter-parts. Therefore, their key structurally distinct information lies in the medium range. The statistics of rings, describing the 3D connection of tetrahedral units, is a crucial indicator of the medium range structure. However, no experimental tech...
Article
Data‐driven science and technology have helped achieve meaningful technological advancements in areas such as materials/drug discovery and health care, but efforts to apply high‐end data science algorithms to the areas of glass and ceramics are still limited. Many glass and ceramic researchers are interested in enhancing their work by using more da...
Article
Full-text available
This work presents a method to 1) statistically characterize the complex geometry of porous material microstructures, 2) parameterize these random microstructures into statistically condense, feature rich metrics, and 3) relate these metrics to material properties such as permeability. This method is applied to porous synthetic cordierite and alumi...
Article
It is challenging to realize both a fully conjugated rigid polymer backbone and high molecular weight at the same time. Previously, we reported a DPP-FT4 polymer with molecular weight up to 30 kDa. A new design and synthesis was required to overcome this limitation. Here, we report the successful synthesis of a conjugated semiconducting polymer wit...
Article
In this work, thermal poling of ternary oxide glasses, including borosilicates and aluminosilicates, is studied using molecular dynamics. For the glass compositions simulated, results show that thermal poling lowers the Young's modulus of those ternary oxide glasses. Additionally, comparisons between the structures of as-melted and poled glasses, a...
Article
Due to its ability to permanently alter key properties of glasses after melting, thermal poling is considered a promising candidate for post-melt processing of glasses. However, in order to take full advantage of this technique, a deeper understanding of the processes involved in the compositional and structural changes observed after poling is nec...
Article
Full-text available
Chemical strengthening via ion exchange, thermal tempering, and lamination are proven techniques for the strengthening of oxide glasses. For each of these techniques, the strengthening mechanism is conventionally ascribed to the linear superposition of the compressive stress (CS) profile on the glass surface. However, in this work, we use molecular...
Article
We evaluate the fracture mechanism in the binary aluminosilicate glasses using molecular dynamics simulations. The simulations using two independent force fields reveal that increasing the alumina content promotes shear and suppresses fracture, thereby increasing the intrinsic ductility, in agreement with experimental observations. In indentation s...
Article
Functional glasses play a critical role in current and developing technologies. These materials have traditionally been designed empirically through trial-and-error experimentation. However, here we report recent advancements in the design of new glass compositions starting at the atomic level, which have become possible through an unprecedented le...
Article
Full-text available
Front Cover: The glass transition behaviors and mechanical properties of the π-conjugated polymers, polyacetylene (PA) and poly(para-phenylene vinylene) (PPV), are predicted using atomistic simulations and compared with experimental measurements. The cover shows a molecular dynamics simulation box consisting of PPV molecules. The box, each side of...
Article
Full-text available
Molecular dynamics (MD) simulations are used to directly observe nucleation of median cracks in oxide glasses under indentation. Indenters with sharp angles can nucleate median cracks in samples with no pre-existing flaws, while indenters with larger indenter angles cannot. Increasing the tip radius increases the critical load for nucleation of the...
Article
Full-text available
Thermophysical and mechanical properties of two conjugated polymers, poly(p-phenylene vinylene) (PPV) and polyacetylene (PA), are predicted using molecular dynamics simulations and compared with results obtained from differential scanning calorimetry, nanoindentation, and dynamic mechanical analysis experiments. Glass transition temperature (Tg) is...
Article
Chemically strengthened glass is one of the key enablers of the modern consumer electronics industry. Molecular dynamics simulations offer an opportunity to build enhanced fundamental understanding of the ion exchange process used for chemical strengthening. In this work, we apply molecular modeling techniques to investigate several aspects of ion-...
Patent
Compounds having a core comprised of an aromatic ring and at least two annulated beta-substituted fused thiophene ring systems of the general formula: -(β-R2—FT2ArFT2-β-R2)—, and polymers or copolymers thereof, of the general formulas: -{-(β-R2—FT2ArFT2-β-R2)-G1-}n-, or -{-G1-(β-R2—FT2ArFT2-β-R2)-G1-G2-}n-, where β-R2—FT2ArFT2-β-R2, -G1-, -G2...
Patent
The disclosure relates to methods for determining mixedness of batch material for making ceramic ware, and methods for obtaining substantially consistent mixedness of batch material for making ceramic ware.
Article
The synthesis and characterization of a fused thiophene-diketopyrrolopyrrole based semiconducting polymer PTDPPTFT4 is presented. A number of synthetic challenges have been overcome in the development of a practical scalable synthesis. Characterization by Gel Permeation Chromatography (GPC) over a range of temperatures has revealed the tendency of...
Article
The chemical strengthening of glass involves the stuffing of large ions into network sites previously occupied by smaller ions. Typically this involves an exchange of Li+ or Na+ ions in the glass for larger K+ ions from a molten salt bath. This swapping of ions creates compressive stress in the surface of the glass, significantly increasing the str...
Article
Chemically strengthened glasses are of increasing technological importance for personal electronic devices, tablet computers, and a variety of other applications. However, there are many unexplained phenomena associated with the physics of the ion exchange process used for strengthening. One of the most puzzling of these is the anomalous behavior o...
Article
Self-diffusion in calcium aluminosilicate glasses was investigated at the atomistic level using molecular dynamics simulations. A study was made of nine glass compositions having a fixed ratio, CaO]/[Al2O3 = 1, where the concentration of SiO2 was varied from 11.8 to 76.5mol%. The diffusion coefficient was calculated for each composition at 300 to 6...
Article
Full-text available
We investigate the heterogeneous dynamics of calcium aluminosilicate liquids across both the peraluminous and peralkaline regimes. Using the isoconfigurational ensemble method we find a clear correlation between dynamical heterogeneities and concentration fluctuations. Regions of high dynamic propensity have higher concentrations of both calcium an...
Article
We investigated the relationship between molecular structure and field-effect hole mobility in a family of fused-ring polythiophene copolymers that we designed recently. The results suggest that a repeat unit that possesses a C(2) axis perpendicular to the conjugation plane is important to achieve a high-mobility. Our finding is supported by a revi...
Article
We present a semi-empirical technique for computation of glass density based on the enthalpy landscape approach. The technique incorporates thermal history and entropy effects into a scaling factor, which is determined using a computed enthalpy versus volume curve and a single experimental density value. We demonstrate the technique on a series of...
Article
With the increasing importance of density in thin films technology, mainly for microelectronic applications, the study of grain growth competition is now one of the most important issues. We use a 2D Level Set method to investigate the influence of temperature and rougthness on the TiN grain growth. Our model includes the physical known effects of...
Article
We investigate the influence of the vacancy densities on the oxide ultrathin films, a cristobalite structure, for the need of the mechanical stress minimization. By means of many body potential energy function, we analyze a structure composed of Si (two unit lattices in each direction), (001) oriented, on which the a cristobalite is grown. The simu...
Article
Using the many body potential and the Metropolis test for energy minimization, we deposit oxygen atoms, one by one, on (001) oriented crystalline silicon 2 × 2 × 3. For temperatures ranging from 295 to 310 K. we allow the structure to relax. In the equilibrium state we investigate the SiO, OO bond length distribution in the oxide. Our simulation...
Article
Over the last two decades, very important research has been made on the Si/SiO2 interface both because of its practical importance in the MOS technology and because of its fundamental interest. The non-crystalline character of the SiO2 overlayer and the inability of the usual experimental tools to investigate the atomic structure at the interface w...
Article
Over the last two decades, very important research has been made on the Si/SiO2 interface both because of its practical importance in the MOS technology and because of its fundamental interest. The non-crystalline character of the SiO2 overlayer and the inability of the usual experimental tools to investigate the atomic structure at the interface w...
Article
By means of molecularsimulation, the analysis of different parameters that influence the nativeoxide crystalline structure is shown. Each of six different oxide clusters is deposited on a silicon unit lattice, [001] oriented, with temperature ranging from 300 K to 320 K. The stress and final energy per atom in the oxide are predominant factors in t...