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Displaying 1276 - 1300 of 2363

Entropy-Driven Structural Transition and Kinetic Trapping in Formamidinium Lead Iodide Perovskite

October 21, 2016

Author(s)

Tianran Chen, Benjamin J. Foley, Changwon Park, Craig Brown, Leland Harriger, Jooseop Lee, Jacob Ruff, Mina Yoon, Joshua J. Choi, Seugn-Hun Lee

A challenge for hybrid perovskite solar cells is device instability, which calls for understanding of the perovskite structural stability and phase transitions. Here, using neutron diffraction and ab-initio calculations on HC(NH 2) 2PbI 3, we show that the

Prediction of entropy stabilized incommensurate phases at X = 0.46, in the system (1-X)-MoS(Sub2)-(X)-MoTe(Sub2)

October 21, 2016

Author(s)

Benjamin P. Burton, Arunima Singh

A first principles phase diagram calculation, that included van der Waals interactions, was performed for the system (1-X)MoS2-(X)MoTe2. Surprisingly, the predicted phase diagram has at least two ordered solid-solution phases, at X = 0.46, even though all

Influence of Pressure on Glass Formation in a Simulated Polymer Melt

October 18, 2016

Author(s)

Jack F. Douglas, Wensheng Xu, Karl Freed

We investigate the thermodynamic and dynamic properties of a model unentangled glass-forming polymer melt over a wide range of pressures (P) and temperatures (T) using molecular dynamics simulation. We show that the T dependence of the reduced thermal

Role of Cohesive Energy in the Thermodynamics and Dynamics of Glass-Forming Polymer Melts

October 18, 2016

Author(s)

Jack F. Douglas, Karl Freed, Wen-Sheng Wu

Monomer molecular and chemical structures represent the most important characteristics of polymers that directly determine the basic molecular parameters (such as cohesive energy) influencing the physical properties of polymer materials. However, a

Supramolecular Self-assembly of a Novel Hydrogelator: Characterization of Fiber Morphology and Formation and Thermal-Reversible Gelation

October 8, 2016

Author(s)

Jack F. Douglas, Yuan Gao Yuan Gao, Ryan C. Nieuwendaal, Emilios Dimitriadis, Boualem Hammouda, Bing Xu, Ferenc Horkay

Hydrogels are of intense recent interest in connection with biomedical applications ranging from 3-D cell cultures and stem cell differentiation to regenerative medicine, controlled drug delivery and tissue engineering. This prototypical form of soft

(Magic Dopant) Amphoteric Behavior of a Redox-Active Transition Metal Ion in a Perovskite Lattice: New Insights on the Lattice Site Occupation of Manganese in SrTiO3

October 5, 2016

Author(s)

Russell A. Maier, Matthew P. Donohue

It is definitively shown for the first time that a transition metal, redox-active ion can exhibit amphoteric substitution in the SrTiO3 perovskite lattice. The manganese dopant is preferably accommodated as Mn2+ on the strontium site and as Mn4+ on the

Correlation Between Morphology and Device Performance of pBTTT:PC 71 BM Solar Cells

October 1, 2016

Author(s)

Wenluan Zhang, Hao Shen, Brett W. Guralnick, Brian Kirby, Ngoc A. Nguyen, Roddel Remy, Charles Majkrzak, Michael E. Mackay

Phenyl-C 71-butyric acid methyl ester (PC 71BM) could intercalate between the side-chains of poly(2,5-bis(3-tetradecylthiophen-2-yl)thieno[3,2-b]thiophene (pBTTT) creating a stable co-crystal structure, so optimal solar cell performance was obtained at

Mechanical/Structural Properties of the Key Thin Film Materials Ag, Cu & Ni for Electronics Applications

September 23, 2016

Author(s)

Daniel Josell, Yousuf Mohammed, Helmut Baumgart, Abdelmageed Elmustafa

Metallic films of Ag, Cu, and Ni each of 150, 300, 600 and 1000 nm thick were deposited on Si using an electron-beam evaporation (e-beam) deposition system. A shutter was used to successively cover increments of 1" (2.54 cm) of the wafer at a time

Superconformal Bottom-Up Cobalt Deposition in High Aspect Ratio Through Silicon Vias

September 23, 2016

Author(s)

Daniel Josell, Manoj R. Silva, Thomas P. Moffat

This work demonstrates void-free cobalt filling of 56 um tall, annual Through Silicon Vias (TSVs) using a mechanism that couples suppression breakdown and surface topography to achieve controlled bottom-up deposition. The chemistry, a Watts electrolyte

Superconformal Bottom-Up Nickel Deposition in High Aspect Ratio Through Silicon Vias

September 23, 2016

Author(s)

Daniel Josell, Thomas P. Moffat

Abstract: This work demonstrates void-free nickel filling of 56 μm tall, annular Through Silicon Vias (TSVs) using a mechanism that couples suppression breakdown and surface topography to achieve controlled superconformal, void-free deposition. The

The Suppression Breakdown induced S-NDR Mechanism for Defect-Free Filling of High Aspect Ratio Features

September 23, 2016

Author(s)

Daniel Josell, Thomas P. Moffat

Superconformal electrodeposition in Through Silicon Vias for multiple metal systems is summarized and shown to be explained by models based on suppressor-induced, S-shaped negative differential resistance (S-NDR). Just published results for superconformal

Atomically Engineered Ferroic Layers Yield a Room-Temperature Magnetoelectric Multiferroic

September 21, 2016

Author(s)

Julia A. Mundy, Charles M. Brooks, Megan E. Holtz, Jarrett A. Moyer, Hena Das, Alejandro F. Rebola, John T. Heron, James D. Clarkson, Steven M.T. Disseler, Zhiqi Liu, Alan Farhan, Rainer Held, Robert Hovden, Elliot Padgett, Qingyun Mao, Hanjong Paik, Rajiv Misra, Lena F. Kourkoutis, Elke Arenholz, Andreas Scholl, Julie Borchers, William D. Ratcliff, Ramamoorthy Ramesh, Craig J. Fennie, Peter Schiffer, David A. Muller, Darrell G. Schlom

The defining feature of ferroics is the ability of an external stimulus - electric field, magnetic field, or stress-to move domain walls. These topological defects and their motion enables many useful attributes, e.g., memories that can be reversibly

The Glass Transition of a Single Macromolecule

September 21, 2016

Author(s)

Jack F. Douglas, David Simmons, Weston L. Merling, Jack Mileski

The glass transition of a single macromolecule in isolation is relevant to the dynamics of systems including dilute solutions of synthetic polymers and biological macromolecules such as proteins. Here we employ molecular dynamics simulation to show that a

An Improved 2-Port Transmission Line Permittivity and Permeability Determination Method with Shorted Sample

September 20, 2016

Author(s)

Derek A. Houtz, Dazhen Gu, Dave K. Walker

A modified measurement technique and nonlinear least-squares solution method is introduced for determining complex permittivity and permeability in transmission lines. In addition to a 2-port S-parameter measurement, a 1-port measurement of the shorted

A Q-band free-space characterization of carbon nanotube composites

September 19, 2016

Author(s)

Ahmed M. Hassan, Jan Obrzut, Edward Garboczi

We present a free-space measurement technique for non-destructive non-contact electrical and dielectric characterization of nano-carbon composites in the Q-band frequency range of 30 GHz to 50 GHz. The experimental system and error correction model

The Center for Research on Extreme Batteries

September 19, 2016

Author(s)

Eric Wachsman, Cynthia Lundgren, Esther S. Takeuchi, Kang Xu, Chunsheng Wang, Joseph Dura, David L. Jacobson, Kahlil Amine, William Acker

How much would you spend on a battery if your life depended on it? Rarely is that question asked as the vast majority of battery development is focused on bringing down battery cost for wide spread consumer acceptance. However, for many industries

Towards Building Simulation Tools for Next Generation Soft Body Armour Testing Standards

September 18, 2016

Author(s)

Steven P. Mates, Amanda L. Forster, Michael A. Riley, Kirk D. Rice, Juliana Ivancik

Accurate simulation tools for soft body armour testing would vastly improve test designer's ability to optimize and refine standards by supplying quantitative information about the influence of test variables on test outcomes. Such tools would also

Nanomanufacturing Concerns about Measurements Made in the SEM Part V. Dealing with Noise

September 17, 2016

Author(s)

Michael T. Postek, Andras Vladar

Scanning electron microscopes (SEM) are used extensively in research and advanced manufacturing for materials characterization, metrology and process control. Unfortunately, noise can limit the specimen-specific detail and information that can be acquired

Film morphology evolution during solvent vapor annealing of highly efficient small molecule donor/acceptor blends

September 15, 2016

Author(s)

Sebastian Engmann, Hyun W. Ro, Andrew Herzing, Chad R. Snyder, Lee J. Richter, Paul Geraghty, David Jones

Solution-processable small molecule photovoltaics based on the novel molecular donor, benzodithiophene terthiophene rhodamine (BTR), recently have shown maximum power conversion efficiencies above 8% for active layer thicknesses up to 400 nm, using post

Thermodynamics of Cottrell atmospheres tested by atomistic simulations

September 15, 2016

Author(s)

Yuri Mishin, John W. Cahn

Solute atoms can segregate to elastically deformed lattice regions around a dislocation and form an equilibrium distribution called the Cottrell atmosphere. We compare two approaches to describe Cottrell atmospheres. In the Eshelby theory, the solid

Three-Dimensional Protonic Conductivity in Porous Organic Cage Solids

September 13, 2016

Author(s)

Ming Liu, Linjiang Chen, Scott Lewis, Samantha Y. Chong, Marc A. Little, Tom Hasell, Iain M. Aldous, Craig Brown, Martin W. Smith, Carole A. Morrison, Laurence J. Hardwick, Andrew I. Cooper

Proton conduction is a fundamental process in biology and in devices such as proton exchange membrane fuel cells. To maximize proton conduction, 3-D conduction pathways are preferred over 1-D pathways, which prevent proton conduction in two-dimensions

Conformational Nature of DNAGrafted Chains on Spherical Gold Nanoparticles

September 10, 2016

Author(s)

Jack F. Douglas, Fernando Vargas-Lara

We investigate the conformational state of a simple, coarsegrained molecular model for singlestranded DNA chains (ss-DNA) grafted onto spherical symmetric gold nanoparticles (NPs) and of the grafted layer as a whole by molecular dynamic simulations. In

Stabilizing Electrodeposited Nanoparticle Electrocatalysts on Si MIS Photocathodes

September 9, 2016

Author(s)

Thomas P. Moffat

Electrodepositing low loadings of metallic nanoparticle catalysts onto the surface of semiconducting photoelectrodes is a highly attractive approach for decreasing catalyst costs and minimizing optical losses. However, securely anchoring nanoparticles to

Structural and Dynamical Trends in Alkali-Metal Silanides Characterized by Neutron-Scattering Methods

September 2, 2016

Author(s)

Wan Si NMN Tang, Mirjana NMN Dimitrievska, Jean-Noel Chotard, Wei Zhou, Raphael Janot, Alexander V. Skripov, Terrence J. Udovic

Structural, vibrational, and dynamical properties of the mono- and mixed-alkali silanides (MSiH 3, where M=K, Rb, Cs, K 0.5Rb 0.5Cs 0.5, and Rb 0.5Cs 0.5) were investigated by various neutron experiments, including neutron powder diffraction (NPD), neutron

Characterization of dielectric properties and moisture uptake of cellulose nanocrystals using non-contact microwave cavity

September 1, 2016

Author(s)

Jan Obrzut, Caglar Dogu Emiroglu, Beatriz A. Pazmino, Jack F. Douglas, Jeffrey W. Gilman

Dielectric permittivity of cellulose nanocrystals (CNCs) films was determined using a non-contact resonant cavity perturbation method at 7.3 GHz in quantitative correlation with moisture content. The resonant microwave cavity measurement is sensitive to