Overview

Materials Science is a broad field that encompasses both fundamental research to improve our understanding of traditional materials (bulk metals, ceramics, and polymers), as well as an exploration of ways to design new materials with unique nanoscale structure and properties. More and more, computational modeling and simulation methods are being utilized to uncover new scientific knowledge of very small scale processes within materials, and how to manipulate these processes to form new material structures at the nano- and micro-length scales.

In our group, we utilize a variety of computational methods to study both hard materials (metals and ceramics) and soft matter (colloids, polymers, gels) for applications ranging from thin membranes for chemical separations, energy production, and biomedical devices.

University of Arkansas

The University of Arkansas (Fayetteville, AR) is a rapidly-growing public R1 research university, located within the Ozark Mountains.

Biography

Contact

Dr. Paul Christopher Millett

Assistant Professor

Dept. of Mechanical Engineering

University of Arkansas

pmillett@uark.edu

479.575.2473 (office)

Mail:

863 W. Dickson St.

205 Mechanical Engineering Bldg.

Fayetteville AR 72701

Research Interests

Computational design of advanced membrane nanostructures
Nanoparticle self-assembly in multi-phase liquids
Low-density, nanoporous materials and membranes.
Computational materials science and design

Teaching Interests

Introduction to Materials
Computer Methods
Computational Materials Science

Education

B.E., Civil Engineering, Vanderbilt University
M.S., Civil Engineering, University of Arkansas
Ph.D., Civil Engineering, University of Arkansas

Other information

Research

Financial support for our group has been provided by generous grants from the National Science Foundation, the Department of Energy, and the University of Arkansas. Thank you !!

Nanoparticle Self-Assembly in Phase-Separating Liquid Media

The mutual interactions between phase-separating liquids (such as oil-in-water or polymer blend melts) and dispersed nanoparticles are scientifically challenging to understand. However, they are also very important, as such systems can self-assemble into technologically desirable microstructures. Our group studies nanoparticle-polymer mixtures that evolve to form phase-separated liquid domains with nanoparticle-coated interfaces. Such assemblies can be used to fabricate microporous materials with nanoparticle-coated internal surfaces by freezing the structure and then chemically removing one of the phase domains. Our group is interested in computationally simulating the time evolution of these mixtures from a homogeneous state to the metastable state.

Directed Self-assembly of Block Copolymers for Nanoscale Surface Patterning

The phase separation of block copolymers into ordered, nanoscale domains is a highly promising approach to fabricate nanoscale surface patterns in a scalable and cost-effective manner. One distinct challenge that exists in this field concerns the fact that the self-assembly process typically results in a lack of truly long-range order due to the creation of defects such as grain boundaries and dislocations. A second challenge concerns the fact that for many applications, a regular array of square patterns is preferable to close-packed hexagonal patterns (the latter being the stable phase of the commonly-studied diblock copolymer). This is particularly true for the semiconductor industry.

Our group studies strategies to direct the self-assembly of diblock and triblock copolymers into ordered nanoscale domains with hexagonal or square symmetry. Such structures are important for future microprocessor designs as well as bit-patterned media storage exceeding 5 terabits per square inch.

Microstructure Evolution in Nuclear Materials

Irradiation can drive non-equilibrium microstructural changes in solid-state materials including the formation of gas-filled bubbles, unexpected alloy segregation and precipitation, and prismatic dislocation loop formation. Dr. Millett has studied irradiation effects in nuclear fuel and structural alloys with particular focus on the resultant changes in thermo-mechanical properties. A particular emphasis has been on gas bubble nucleation, growth, and coarsening in uranium dioxide fuels, and the effects on thermal transport.

Group Members

Graduate Students

Undergraduate Students

Joseph Carmack

PhD student

BS: Physics (BYU-Idaho)

Rosario Cervellere

Junior, Mechanical Engineering

Joseph Hill

PhD student

BS: Physics (BYU-Idaho)

Bruce Berry

MS student

BS: Nuclear Engineering (Georgia Tech)

Ian Vance

MS student

BS: Mechanical Engineering (Univ. of Arkansas – Fort Smith)

Publications

2016 (and in progress…)
[72]	Vance IW, Millett PC. Phase-field simulations of pore migration and morphology change in thermal gradients. Under review.	[DOI]
[71]	Millett PC. Mesoscopic Simulations of Coarsening Kinetics within Block-Copolymer/Homopolymer Thin Films. Computational Materials Science 125 (2016) 20-27.	[DOI]
	2015
[70]	Sarollahi M, Mishler J, Bauman SJ, Barraza-Lopez S, Millett PC, Herzog JB. The significance of the number of periods and period size in 2D photonic crystal waveguides. SPIE Proceedings 9556 (2015) 95561B.	[DOI]
[69]	Carmack JM, Millett PC. Numerical Simulations of Bijel Morphology in Thin Films with Complete Surface Wetting. The Journal of Chemical Physics 143 (2015) 154701.	[DOI]
[68]	Millett PC. A time-dependent Ginzburg-Landau model for non-frustrated linear ABC triblock terpolymers. Physical Review E 92 (2015) 022602.	[DOI]
[67]	Zhang Y, Millett PC, Tonks MR, Bai X, Biner SB. Preferential Cu segregation at extended defects in bcc Fe: An atomistic study. Computational Materials Science 101 (2015) 181-188.	[DOI]
	2014
[67]	Millett PC. Electric-field induced alignment of nanoparticle-coated channels in thin-film polymer membranes. The Journal of Chemical Physics 140 (2014) 144903.	[DOI]
[65]	Xu WZ, Zhang YF, Cheng GM, Jian WW, Millett PC, Koch CC, Mathaudhu SN, Zhu YT. Dynamic Void Growth and Shrinkage in Mg under electron irradiation. Materials Research Letters 2 (2014) 176-183.	[DOI]
[64]	Andersson AD, Garcia P, Liu X-Y, Pastore G, Tonks MR, Millett PC, Dorado B, Gaston DR, Andrs D, Williamson RL, Martineau RC, Uberuaga BP, Stanek CR. Atomistic modeling of intrinsic and radiation-enhanced fission gas (Xe) diffusion in UO2±x: Implications for nuclear fuel performance modeling. Journal of Nuclear Materials 451 (2014) 225-242.	[DOI]
[63]	Tonks MR, Zhang Y, Bai X, Millett PC. Investigation of the impact of temperature gradients on grain growth using a phase field model. Materials Research Letters 2 (2014) 23-28.	[DOI]
[62]	Zhang Y, Millett PC, Tonks MR, Bai XM, Biner SB. Molecular dynamics simulations of intergranular fracture in UO2 with nine empirical interatomic potentials. Journal of Nuclear Materials 452 (2014) 296-303.	[DOI]
	2013
[61]	Xu W, Zhang Y, Cheng G, Jian W, Millett PC, Koch CC, Mathaudhu SN, Zhu YT. In-situ atomic-scale observation of irradiation-induced void formation. Nature Communications 4 (2013) 2288.	[DOI]
[60]	Millett PC, Zhang Y, Tonks MR, Biner SB. Consideration of grain size distribution in the diffusion of fission gas to grain boundaries. Journal of Nuclear Materials 440 (2013) 435-439.	[DOI]
[59]	Cheng GM, Yuan H, Jian WW, Xu WZ, Millett PC, Zhu YT. Deformation-induced _ phase in nanocrystalline Mo. Scripta Materialia 68 (2013) 130-133.	[DOI]
[58]	Tonks MR, Millett PC, Nerikar P, Andersson D, Stanek C, Gaston D, Andrs D, Williamson R. 2013. Multiscale development of a fission gas thermal conductivity model: Coupling atomic, meso and continuum level simulations. Journal of Nuclear Materials 440 (2013) 193-200.	[DOI]
[57]	Zhang L, Tonks MR, Gaston D, Peterson J, Andrs D, Millett PC, Biner SB. A quantitative comparison between C0 and C1 elements in solving Cahn-Hilliard equation. Journal of Computational Physics 236 (2013) 74-80.	[DOI]
[56]	Millett PC, Tonks MR, Chockalingam K, Zhang Y, Biner SB. Three dimensional calculations of the effective Kapitza resistance of UO2 grain boundaries containing intergranular bubbles. Journal of Nuclear Materials 439 (2013) 117-122.	[DOI]
[55]	Tonks MR, Zhang Y, Biner SB, Millett PC, Bai X. Guidance to design grain boundary mobility experiments with quantitative phase-field modeling. Acta Materialia 61 (2013) 1373-1382.	[DOI]
[54]	Cheng GM, Jian WW, Xu WZ, Zhang YF, Millett PC, Wolf D, Zhu YT. Dislocations with edge components in nanocrystalline body-centered-cubic Mo. Journal of Materials Research 28 (2013) 1820-1826.	[DOI]
[53]	Cheng GM, Jian WW, Xu WZ, Yuan H, Millett PC, Zhu YT. Grain size effect on deformation mechanisms of nanocrystalline BCC metal. Materials Research Letters 1 (2013) 1-6.	[DOI]
	2012
[52]	Chockalingam K, Tonks MR, Gaston DR, Hales JD, Millett PC, Zhang L. Crystal plasticity with Jacobian-free Newton Krylov. Computational Mechanics 51 (2012) 617-627.	[DOI]
[51]	Millett PC, Zhang Y, Andersson DA, Tonks MR, Biner SB. Random-walk Monte Carlo simulation of intergranular gas bubble nucleation in UO2 fuel. Journal of Nuclear Materials 430 (2012) 44-49.	[DOI]
[50]	Zhang Y, Millett PC, Tonks MR, Biner SB. Deformation twinning in nanocrystalline body-centered-cubic Mo by molecular dynamics simulation. Acta Materialia 60 (2012) 6421-6428.	[DOI]
[49]	Zhang Y, Millett PC, Tonks MR, Zhang L, Biner SB. Molecular dynamics simulations of He bubble nucleation at grain boundaries. Journal of Physics: Condensed Matter 24 (2012) 305005.	[DOI]
[48]	Chockalingam K, Millett PC, Tonks MR. Effects of Intergranular gas bubbles on thermal conductivity. Journal of Nuclear Materials 430 (2012) 166-170	[DOI]
[47]	Millett PC, Tonks MR, Biner SB. Grain Boundary Percolation Modeling of Fission Gas Release in Oxide Fuels. Journal of Nuclear Materials 424 (2012) 176-182.	[DOI]
[46]	Zhang L, Tonks MR, Millett PC, Zhang Y, Chockalingam K, Biner SB. Phase-field modeling of temperature gradient driven pore migration. Computational Materials Science 56 (2012) 161-165.	[DOI]
[45]	Zhang Y, Liu XY, Millett PC, Tonks MR, Andersson DA, Biner SB. Crack tip plasticity in single crystal UO2: Atomistic simulations. Journal of Nuclear Materials 430 (2012) 96-105.	[DOI]
[44]	Millett PC, Tonks MR, Biner SB. Mesoscale modeling of intergranular bubble percolation in nuclear fuels. Journal of Applied Physics 111 (2012) 083511.	[DOI]
[43]	Millett PC. Percolation on grain boundary networks: Application to fission gas release in nuclear fuels. Computational Materials Science 53 (2012) 31-36.	[DOI]
[42]	Zhang Y, Millett PC, Tonks MR, Biner SB. Deformation-twin-induced grain boundary failure. Scripta Materialia 66 (2012) 117-120.	[DOI]
[41]	Tonks MR, Gaston D, Millett PC, Andrs D, Talbot P. An object-oriented finite element framework for multiphysics phase field simulation. Computational Materials Science 51 (2012) 20-29.	[DOI]
[40]	Millett PC, Tonks MR, Biner SB, Zhang L, Chockalingam K, Zhang Y. Phase-field simulation of intergranular bubble growth and percolation in bicrystals. Journal of Nuclear Materials 425 (2012) 130-135.	[DOI]
[39]	Zhang Y, Huang H, Millett PC, Tonks MR, Wolf D, Phillpot D. Atomistic study of grain boundary sink strength under prolonged electron irradiation. Journal of Nuclear Materials 422 (2012) 69-76.	[DOI]
	2011
[38]	Zhang Y, Millett PC, Tonks MR. Energetics and diffusional properties of He in BCC Mo: An empirical potential for molecular dynamics simulations. Computational Materials Science 50 (2011) 3224-3229.	[DOI]
[37]	Tonks MR, Millett PC. Phase field simulations of elastic deformation-driven grain growth in 2-D copper polycrystals. Materials Science and Engineering A 528 (2011) 4086-4091.	[DOI]
[36]	Millett PC, Tonks MR. Application of phase-field modeling to irradiation effects in materials. Current Opinion in Solid State and Materials Science 15 (2011) 125-133.	[DOI]
[35]	Millett PC, Tonks MR. Mesoscale modeling of the influence of intergranular gas bubbles on effective thermal conductivity. Journal of Nuclear Materials 412 (2011) 281-286.	[DOI]
[34]	Millett PC, Wang YU. Diffuse-interface field approach to modeling arbitrarily-shaped particles at fluid-fluid interfaces. Journal of Colloid and Interface Science 353 (2011) 46-51.	[DOI]
[33]	Millett PC, Tonks MR. Phase-field simulations of gas density within bubbles under irradiation. Computational Materials Science 50 (2011) 2044-2050.	[DOI]
[32]	Millett PC, El-Azab A, Wolf D. Phase field simulation of irradiated metals: Part II: Gas bubble kinetics. Computational Materials Science 50 (2011) 960-970.	[DOI]
[31]	Millett PC, El-Azab A, Rokkam S, Tonks M, Wolf D. Phase field simulation of irradiated metals: Part I: Void kinetics. Computational Materials Science 50 (2011) 949-959.	[DOI]
	2010
[30]	Tonks M, Millett PC, Cai W, Wolf D. Analysis of the elastic strain energy driving force for grain boundary migration using phase field simulation. Scripta Materialia 63 (2010) 1049-1052.	[DOI]
[29]	Tonks M, Gaston D, Permann C, Millett PC, Hansen G, Wolf D. A coupling methodology for mesoscale-informed nuclear fuel performance codes. Nuclear Engineering and Design 240 (2010) 2877-2883.	[DOI]
[28]	Desai T, Millett PC, Tonks M, Wolf D. Atomistic simulations of void migration under thermal gradient in UO2. Acta Materialia 58 (2010) 330-339.	[DOI]
	2009
[27]	Millett PC, Rokkam S, El-Azab A, Wolf D. Void nucleation and growth in polycrystalline metals: A phase-field model. Modelling and Simulation in Materials Science and Engineering 17 (2009) 064003.	[DOI]
[26]	Aidhy DP, Millett PC, Desai T, Wolf D, Phillpot S. Kinetically-evolving irradiation-induced point defect clusters in UO2. Physical Review B 80 (2009) 104107.	[DOI]
[25]	Millett PC, Wang YU. Diffuse-interface field approach to modeling and simulation of self-assembly of charged colloidal particles with various shapes and sizes. Acta Materialia 57 (2009) 3101-3109.	[DOI]
[24]	Rokkam SK, El-Azab A, Millett PC, Wolf D. Phase field simulation of void nucleation and growth in irradiated metals. Modelling and Simulation in Materials Science and Engineering 17 (2009) 064002.	[DOI]
[23]	Millett PC, Aidhy DP, Desai T, Phillpot SR, Wolf D. Grain-boundary source/sink behavior for point defects: An atomistic simulation study. International Journal of Materials Research 100 (2009) 550-555.	[DOI]
[22]	Aidhy DP, Millett PC, Wolf D, Phillpot SR, Huang H. Kinetically driven point-defect clustering in irradiated MgO by molecular-dynamics simulation. Scripta Materialia 60 (2009) 691-694.	[DOI]
	2008
[21]	Millett PC, Desai T, Yamakov V, Wolf D. Time scale for point-defect equilibration in nanostructures. Applied Physics Letters 93 (2008) 161902.	[DOI]
[20]	Millett PC, Desai T, Wolf D, Rokkam S, El-Azab A. Phase-field simulation of thermal conductivity in porous polycrystalline microstructures. Journal of Applied Physics 104 (2008) 033512.	[DOI]
[19]	Millett PC, Desai T, Yamakov V, Wolf D. Atomistic simulations of diffusional creep in a nanocrystalline bcc material. Acta Materialia 56 (2008) 3688-3698.	[DOI]
[18]	Desai T, Millett PC, Wolf D. Molecular dynamics study of diffusional creep in nanocrystalline UO2. Acta Materialia 56 (2008) 4489-4497.	[DOI]
[17]	Desai T, Millett PC, Wolf D. Is diffusion creep the cause for the inverse Hall-Petch effect in nanocrystalline materials? Materials Science and Engineering A 493 (2008) 41-47.	[DOI]
	2007 (and earlier…)
[16]	Millett PC, Selvam RP, Saxena A. Stabilizing nanocrystalline materials with dopants. Acta Materialia 55 (2007) 2329-2336.	[DOI]
[15]	Millett PC, Selvam RP, Saxena A. Improving grain boundary sliding resistance with segregated dopants. Materials Science and Engineering A 431 (2006) 92-97.	[DOI]
[14]	Millett PC, Selvam RP, Saxena A. Molecular dynamics simulations of grain size stabilization in nanocrystalline materials by addition of dopants. Acta Materialia 54 (2006) 297-303.	[DOI]
[13]	Millett PC, Selvam RP, Bansal S, Saxena A. Atomistic simulation of grain boundary energetics – effects of dopants. Acta Materialia 53 (2005) 3671-3678.	[DOI]
[12]	Selvam RP and PC Millett. Large eddy simulation of the tornado-structure interaction to determine structural loadings. Wind and Structures: An International Journal 8 (2005) 49-60.	[DOI]
[11]	Selvam RP and PC Millett. Computer modeling of tornado forces on buildings. Wind and Structures: An International Journal 6 (2003) 209-220.	[DOI]
[10]	Selvam RP and PC Millett. Computer Modeling of Tornado Forces on a Cubic Building Using Large Eddy Simulation. Journal of the Arkansas Academy of Sciences 57 (2003) 140-146.	[DOI]

Conference Proceedings

[9]	Rokkam SK, Millett PC, Wolf D, El-Azab A. 2008. Phase-field simulation of void growth in irradiated materials. Multiscale Materials Modeling (MMM) Proceedings, p. 405-408.
[8]	Millett PC, Selvam RP. 2005. Molecular dynamics study of the effect of dopant atoms on grain boundary sliding. Materials Research Society Proceedings vol 903E:Z5.42 Nov. 28 – Dec 2, Boston, MA.
[7]	Saxena A, Millett PC, Selvam RP, Bansal S. 2005. Application of molecular dynamics in designing stable nanostructures. International Conf. on Advanced Materials Design and Development. Gao, India. December 14-16.
[6]	Millett PC, Riordan J, Selvam RP. 2005. Computation of moment coefficients on a cubic building due to tornado. 10th Americas Conference on Wind Engineering. May 31-June 4, Baton Rouge, LA.
[5]	Millett PC, Selvam RP, Saxena A. 2004. Molecular dynamics study of the prevention of grain growth in nanocrystalline materials by use of doping. Materials Research Society Proceedings vol 854E:U6.10 Nov. 29 – Dec. 3, Boston, MA.
[4]	Millett PC, Selvam RP, Bansal S, Saxena A. 2004. Atomistic simulation of the effects of doping in the vicinity of a copper bicrystal grain boundary. Meeting of the Arkansas Academy of Sciences.
[3]	Selvam RP and PC Millett. 2003. Computer Modeling of the Tornado-Structure Interaction on a Cubic Building. 11th International Conference on Wind Engineering. Texas Tech University, June 2-5. p. 837-844.
[2]	Selvam RP and PC Millett. 2003. Computer Modeling of Tornado Forces on a Cubic Building Using Large Eddy Simulation. Meeting of the Arkansas Academy of Sciences.
[1]	Selvam RP and PC Millett. 2002. Computer Modeling of the Tornado-Structure Interaction: Investigation of Structural Loading of Cubic Building. Second International Conference on Fluid Mechanics and Fluid Power. Indian Institute of Technology-Roorkee, India. December 12-14.

Teaching

MEEG 2303 – INTRODUCTION TO MATERIALS

This course introduces students to the internal structure and basic properties of engineering materials, including metals, ceramics, and polymers. Connections between material microstructure at difference length scales and mechanical strength, ductility, and fracture resistance are emphasized.

Text: Essentials of the Science and Engineering of Materials, 3rd Ed. (Askeland and Wright), 2013

Previous Semesters

Fall 2015 :: Syllabus :: Average evaluation: 4.7/5.0
Fall 2014 :: Syllabus :: Average evaluation: 4.6/5.0
Spr 2014 :: Syllabus :: Average evaluation: 4.7/5.0
Fall 2013 :: Syllabus :: Average evaluation: 4.8/5.0

MEEG 2703 – COMPUTER METHODS IN MECHANICAL ENGINEERING

This course introduces students to numerical methods formulated to solve engineering problems. Topics include solving non-linear equations, matrix methods, optimization, curve-fitting, integration and differential equations. Emphasis is placed on specific algorithms and MATLAB/EXCEL programming.

Text: Numerical Methods for Engineers, 7th Ed. (Chapra and Canale), 2015

Previous Semesters

Spr 2015 :: Syllabus :: Average evaluation: 4.5/5.0

News

Announcements

2016

03/16: Joseph Hill gives first international conference presentation at APS! Congratulations!

2015

12/15: Joseph Carmack presents paper at MRS Fall Meeting in Boston! Great job!

09/15: Joseph Carmack’s paper accepted in Journal of Chemical Physics!

08/15: Dr. Millett’s paper on triblock terpolymer model accepted in Physical Review E.

07/15: Dr. Millett awarded NSF grant to study self-assembled membranes, collaboration with Miko Cakmak (Univ. of Akron).

05/15: Dr. Millett named Most Outstanding Researcher in MEEG (2015).

03/15: Nice Newswire feature on Joe Carmack [Link]

02/15: Ian Vance joins the Millett research group. Welcome to the UofA!

01/15: Bruce Berry joins the Millett research group. Welcome to the UofA!

2014

08/14: Dr. Millett awarded NEUP grant from DOE in collaboration with Chaitanya Deo (Georgia Tech), Sean McDeavitt (Texas A&M), and Bob Mariani (INL).

08/14: New compute nodes purchased by Millett are online at AHPCC! A total of 512 processors!

08/14: Joe Hill begins PhD program. Welcome, Joe!

05/14: FIRST ACADEMIC YEAR IS IN THE BOOKS! It’s been a great year, and I’m so glad to be at the Univ. of Arkansas. Great students, great colleagues.

03/14: Joe Hill is offered Distinguished Doctoral Fellowship by the UA. Very Exciting! Joe will join Millett Group in August 2014.

03/14: Dr. Millett presents research at UA Sigma Xi meeting.

03/14: Dr. Millett’s paper on nanoparticle-polymer membranes accepted in Journal of Chemical Physics.

02/14: Dr. Millett & Joe Carmack attend TMS conference; Joe gives first international research presentation of his career!

2013

09/13: Dr. Millett presents research at UA Physics Dept. graduate colloquium.

08/13: Joseph Carmack awarded Doctoral Academy Fellowship by UA (congratulations!).

08/13: Joseph Carmack joins Millett research group.

Arkansas Newswire and Press

04/07/16: U of A Honors 15 Faculty and Staff Grant Recipients

08/21/15: NSF Grant Supports Development of Nanoparticle Porous Membranes

08/04/15: University of Arkansas to Lead New Center With Industrial Solutions Focus

03/17/15: Doctoral Fellow Working to Develop Next Generation of Materials

10/28/14: U.S. Department of Energy Grant Will Further Study of Safer, More Efficient Nuclear Reactors

09/08/14: University of Arka nsas Students Honored at SPIE Conference

09/23/13: New Mechanical Engineering Professor Models Nanomat erials