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Publications

Search Publications by Jonathan E. Guyer

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Displaying 1 - 25 of 38

Phase Field Benchmark Problems Targeting Fluid Flow and Electrochemistry

January 28, 2020
Author(s)
Andrea Jokisaari, Wenkun Wu, P W. Voorhees, Jonathan E. Guyer, James A. Warren, Olle G. Heinonen
In this work, a third set of benchmark problems for phase field models are presented. These problems are being jointly developed by the Center for Hierarchical Materials Design (CHi- MaD) and the National Institute of Standards and Technology (NIST) along

PFHub: The Phase-Field Community Hub

April 17, 2019
Author(s)
Daniel Wheeler, Trevor Keller, Jonathan E. Guyer, James A. Warren, Stephen DeWitt, Andrea Jokisaari, Daniel Schwen, Larry Aagesen, Olle Heinonen, Michael Tonks, Peter Voorhees
An online portal provides a valuable space for scientific communities to summarize a shared challenge, collect attempts at a solution, and present a quantitative comparison of past attempts in a compelling way. An exemplar of such a portal is μMAG. The

Phase Field Benchmark Problems for Dendritic Growth and Linear Elasticity

June 15, 2018
Author(s)
Andrea Jokisaari, P W. Voorhees, Jonathan E. Guyer, James A. Warren, O. G. Heinonen
We present the second set of benchmark problems for phase field models that are being jointly developed by the Center for Hierarchical Design (CHiMaD) and the National Insti- tute of Standards and Technology (NIST) along with input from other members in

Formation of Nb-rich droplets in laser deposited Ni-matrix microstructures

March 15, 2018
Author(s)
Supriyo Ghosh, Mark R. Stoudt, Lyle E. Levine, Jonathan E. Guyer
Ni-rich $\gamma$ cells/dendrites and Nb-rich eutectic droplets that form during laser power bed fusion (LPBF) solidification of Ni-Nb alloys are studied in the present work using numerical simulations. Finite element simulations estimate the local cooling

Single Track Melt Pool Measurements and Microstructures in Inconel 625

February 20, 2018
Author(s)
Supriyo Ghosh, Li Ma, Lyle E. Levine, Richard E. Ricker, Mark R. Stoudt, Jarred C. Heigel, Jonathan E. Guyer
We use single track laser melting experiments and simulations on Inconel 625 to estimate the dimensions and microstructures of the resulting melt pools. Our work is based on a design-of- experiments approach which uses multiple laser power and scan speed

Application of Finite Element, Phase-field, and CALPHAD-based Methods to Additive Manufacturing of Ni-based Superalloys

September 21, 2017
Author(s)
Trevor Keller, Greta Lindwall, Supriyo Ghosh, Li Ma, Brandon M. Lane, Fan Zhang, Ursula R. Kattner, Eric Lass, Yaakov S. Idell, Maureen E. Williams, Andrew J. Allen, Jonathan E. Guyer, Lyle E. Levine
Numerical simulations are used in this work to investigate aspects of microstructure and microsegregation during rapid solidification of a Ni-based superalloy in a laser powder bed fusion additive manufacturing process. Thermal modeling by finite element

Benchmark Problems for Phase Field Modeling

January 2, 2017
Author(s)
Andrea Jokisaari, P W. Voorhees, Jonathan E. Guyer, James A. Warren, O. G. Heinonen
We present the first set of benchmark problems for phase field models that are being devel- oped by the Center for Heirarchical Materials Design (CHiMaD) and the National Institute of Standards and Technology (NIST). While many scientific research areas

Windowless CdSe/CdTe Solar Cells with Differentiated Back Contacts: J-V, EQE and Photocurrent Mapping

August 26, 2016
Author(s)
Daniel Josell, Ratan K. Debnath, Jong Yoon Ha, Jonathan E. Guyer, Nhan V. Nguyen, M. A. Sahiner, C Reehil, W. A. Manners
This paper presents a study of windowless CdSe/CdTe thin film photovoltaic devices with in-plane patterning at a submicrometer length scale. The photovoltaic cells are fabricated upon two interdigitated comb electrodes pre-patterned at micrometer length

A multicomponent phase-field model for extremely large partition coefficients

January 31, 2014
Author(s)
Michael J. Welland, Dieter Wolf, Jonathan E. Guyer
We develop a multi-component phase-field model specially formulated to robustly simulate concentration variations from molar to atomic magnitudes across an interface, i.e.: partition coefficients in excess of 10 (superscript 10plus23) such as may be the

Backcontact CdSe/CdTE Windowless Solar Cells

February 1, 2013
Author(s)
Donguk Kim, Carlos M. Hangarter, Ratan K. Debnath, Jong Y. Ha, Carlos R. Beauchamp, Matthew D. Widstrom, Jonathan E. Guyer, Nhan Van Nguyen, B. Y. Yoo, Daniel Josell
This paper details the fabrication and properties of CdSe/CdTe thin film photovoltaic devices with a dual back contact geometry. Device fabrication involves cadmium selenide electrodeposition on one of two interdigitated electrodes on a pre-patterned

The Effect of Substrate Material on Silver Nanoparticle Antimicrobial Efficacy

December 1, 2010
Author(s)
Benita Dair, Dave M. Saylor, T. E. Cargal, Grace R. French, Kristen M. Kennedy, Rachel S. Casas, Jonathan E. Guyer, James A. Warren, Steven K. Pollack
With the advent of Nanotechnology, silver nanoparticles increasingly are being used in coatings, especially in medical device applications, to capitalize on their antimicrobial properties. The increased antimicrobial efficacy of nanoparticulate silver

Predicting Microstructure Development During Casting of Drug Eluting Coatings

September 19, 2010
Author(s)
David M. Saylor, Jonathan E. Guyer, Daniel Wheeler, James A. Warren
We have devised a novel diffuse interface formulation to model the development of chem- ical and physical inhomogeneities, i.e. microstructure, during the process of casting drug eluting coatings. These inhomogeneities, which depend on the coating

Three-Dimensionally Structured Thin Film Heterojunction Photovoltaics on Interdigitated Back-Contacts

February 1, 2010
Author(s)
Daniel Josell, Carlos R. Beauchamp, Behrang H. Hamadani, Suyong S. Jung, Jonathan E. Guyer, Abhishek Motayed, Carlos M. Hangarter, Nadine E. Gergel-Hackett, Hua Xu, Nikolai B. Zhitenev
Fabrication and properties of three-dimensionally structured back-contact heterojunction solar cells are described. A variety of devices are explored, all of which were fabricated by electrochemical deposition of a semiconducting material on one of two

Diffusion Under Temperature Gradient: A Phase-field Model Study

August 11, 2009
Author(s)
Rashmi R. Mohanty, Jonathan E. Guyer, Yong Ho Sohn
A diffuse interface model was devised and employed to investigate the effect of thermotransport (a.k.a., thermomigration) process in single-phase and multi-phase alloys of a binary system. Simulation results show that an applied temperature gradient can

FiPy: PDEs in Python

February 23, 2009
Author(s)
Jonathan E. Guyer, Daniel Wheeler, James A. Warren
Partial differential equations (PDEs) are ubiquitous to the mathematical description of physical phenomena. They describe the relationships between functions of more than one independent variable and partial derivatives with respect to those variables

Kinetics Governing Phase Separation of Nanostructured Sn(x)Ge(1a 'x) Alloys.

June 5, 2006
Author(s)
Regina Regan, Harry A. Atwater, Jonathan E. Guyer, Erik Meserole, Mark S. Gorrsky
We have studied the dynamic phenomenon of SnxGe1a 'x/Ge phase separation during deposition by molecular beam epitaxy on Ge(001) substrates.Phase-separation leads to the formation of direct bandgap semiconductor nanowire arrays embedded in Ge oriented along

FiPy: A Finite Volume PDE Solver Using Python

September 1, 2005
Author(s)
Daniel Wheeler, Jonathan E. Guyer, James A. Warren
The solution of coupled sets of partial differential equations (PDEs) is ubiquitous in continuum models for phase transformations, such as in phase field or level et simulations. We are developing an object-oriented PDE solver, written in the Python

Phase-Field Modeling for Eutectic Solidification

April 1, 2004
Author(s)
Jonathan E. Guyer, William J. Boettinger, James A. Warren, Geoffrey B. McFadden
A diffuse interface (phase field) model for a simple electrochemical system is developed. We describe the minimal set of components needed to model an electrochemical interface and present a Lagrangian derivation of te governing equations. With a simple

Phase Field Modeling of Electrochemistry. II. Kinetics

February 1, 2004
Author(s)
Jonathan E. Guyer, William J. Boettinger, James A. Warren, Geoffrey B. McFadden
The kinetic behavior of the phase field model described in (J.E. Guyer, W.J. Boettinger, J.A. Warren and G. B. McFadden, Phase field modeling of electrochemistry: Equilibrium, unpublished) is explored for advancing (plating) and receding (corroding)

Phase Field Modeling of Electrochemistry. I. Equilibrium

February 1, 2004
Author(s)
Jonathan E. Guyer, William J. Boettinger, James A. Warren, Geoffrey B. McFadden
A diffuse interface (phase field) model for an electrochemical system is developed. We describe the minimal set of components needed to model an electrochemical interface and present a variational derivation of the governing equations. With a simple set of