Measuring and improving mechanical behavior of ceramics and other materials, modelling the processing of ceramics, developing new ceramic materials with interesting properties.

Gerberich Research Group

Professor of Materials Science and Engineering    

  • Research
  • Professional Activities
  • Students
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Our graduate student research group currently emphasizes mechanical behavior of small volumes such as nanospheres and failure at bi-material interfaces. This ranges from strained-layer epitaxy of microelectronic materials to polystyrene/silicon interfaces. Materials of interest have included nanospheres of silicon, SiC and Ti; Si, NiAl and Fe-3wt%Si single crystals; and InGaAs/GaAs, Co/Si, PS/PMMA, DLC/MgO, and Cu/Si thin films. Micromechanical modeling and single crystal studies are primarily aimed at understanding the underlying mechanisms for fatigue, fracture, toughness, and strength. The principal goal is life prediction for all types of microstructurally influenced interface structures. We have recently started four initiatives with which to better understand the integrity of materials. One is real-time imaging of nanomechanical and micromechanical processes with AFM, TEM, and FEG-SEM (field emission gun scanning electron microscopy). An example of this is in situ fracture of silicon nanospheres. Such a nanoindentation instrument is currently being installed in our newest TEM (Tecnai). A second example is nanoindentation induced dislocation emission in ceramic and metallic single crystals, thin films, and nanospheres. Surfaces undergoing nanoindentation can be imaged by atomic force microscopy directly before and after revealing nanometer scale cavities. A third is the removal of copper thin films processed by microlithography to represent test structures for adhesion analysis by nanoindentation.

With the failure of any of these microelectronic or structural interfaces, analysis ranges from the nanoscopic to the macroscopic. All of these studies use powerful experimental tools--such as selected area channeling and thin-film electron microscopy, nanoindentation and atomic force microscopy--in conjunction with analysis techniques provided by continuum and atomistic theory.

Professional Activities

Summary of significant professional activities for William W. Gerberich for the 2009-2010 academic year (April 1, 2010 – March 31, 2011).


Fall 2010: MatS 4221 – Materials Design and Performance (Lecture/Lab)
Spring 2011: MatS 2001 – Intro to Science of Engineering Materials
Graduate Advising: 3 PhD students (2 are co-advised), 3 MS Students.

University/Department Service

P.I. on four interdisciplinary programs: [ T. Dumitrica (1); Jeff Derby, A. Mkhoyan (1)] NSF DMR 0946337 Award with C. Leighton 12/15/09 (1); INL/DOE #000109759 Awarded January 2011, with A. Mkhoyan.

Professional Service:

  • Editorial Committee, Japan Institute of Metals, Materials Transactions
  • Associate Editor, J. Strength, Fracture and Complexity
  • Editorial Board of Review, Metals and Materials Transactions
  • Advisory Board, Key Engineering Materials
  • National Academy of Science Review Panel of NIST, Materials Science and Engineering Laboratories @ Boulder and Gaithersburg, Feb.-March 2010
  • Thomson-Reuters Highly –Cited Publication List for Materials Science, 9/15/09
  • Lead Intro. To Encyclopedic Vol. : Damage Mechanisms, Historical in Gaseous Hydrogen Embrittlement of High Performance Metals, Woodhead Publishing, UK, Cambridge (in press).

International Cooperative Ventures:

  • ADMIRE: IRG 4.1 (Seed) Processing Improved Microstructures
  • Abu Dhabi for the Energy Industry, J.J. Derby, W.W. Gerberich, A. Mkhoyan, initiated January 2009.
  • AFOSR: An AOARD Grant to facilitate cooperation with Professor Yuichi Ikuhara, University of Tokyo, “Size scale and defect engineered nanostructures for optimal strength and toughness.” September 2008 – October 2010. An undergraduate student, Hiroto Kimura, from Tokyo Institute of Technology was hosted for three months, Fall 2009.
  • EMPA, Thun, Switzerland: An interaction with Dr. Johann Micheler’s group featuring in situ nanoindentation deformation inside both TEMs (Minnesota) and SEMs (EMPA), initiated in 2008 has resulted in two papers, in 2009, 2010.
  • Helsinki University of Technology: A joint program with Professor R. Nowak’s group facilitating experiments and molecular dynamics simulation of silicon and sapphire nanostructures has resulted in one accepted paper submitted 2011.

Invited Talks and Seminars:

  • Aerospace and Engineering Mechanics Seminar, “Experimental Input to Multiscale Modeling, University of Minnesota, 4/6/10.
  • Center for Advance Vehicular Systems, CAVS 10 Workshop, “Experimental Input to Multiscsale Modeling, Mississippi State University, June 23, 2010.
  • Dislocation Nucleation and Dynamics in Silicon Nanopillars Cambridge University, September 19, 2010.
  • Dislocation Nucleation and Dynamics in Silicon Nanopillars, Queen Mary (Physics), University of London, September 23, 2010.
  • A Size-Scale Brittleness Transition for Silicon, The Materials Society (TMS), San Diego, CA, March 1.
  • Dislocation Hardening in Silicon Single Crystals, The Materials Society (TMS), San Diego, CA, March 2.
  • CAN, Center for Nanostructural Applications Series, “In Situ Nanomechanics for Advanced Structures, University of Minnesota, March 21, 2011.

List of Refereed Publications:

  • J. D. Nowak, A.R. Beaber, O. Ugurlu, S.L. Girshick and W.W. Gerberich, “Small size strength dependence on dislocation nucleation, Scripta Materialia, 62 (2010) 819-822.
  • A. Beaber and W. Gerberich, “Strength from modeling,” Nature Matrials, 9, (2010) 698-699.
  • D.D. Stauffer, R.C. Major, D. Vodnick, J.H. Thomas III, J. Parker, M. Manno, C. Leighton and W.W. Gerberich “Plastic response of the native oxide on Cr and Al thin films from in situ conductive nanoindentation, “ Acta Materialia, submitted (2010).
  • D. Chrobak, N. Tymiak, A. Beaber, O. Ugurlu, W.W. Gerberich and R. Nowak, “From bulk to nanoparticles: Deconfining nanovolume signals a shift in material properties,” Nature Nanotechnology, submitted (2011).
  • A. Beaber and W. Gerberich, “Strength from Modelling,” Nature Materials, 9,(2010) 698-699.
  • L. M. Hale, X. Zhou, J.A. Zimmerman, N.R. Moody, R., Ballarini and W.W. Gerberich, “Phase transformations, dislocations and hardening in uniaxially compressed silicon nanospheres,” Computational Materials Science, 50 (2011) 1651-1660.
  • L. Hale, D.-B. Zhang, X. Zhou, J. A. Zimmerman, N.R. Moody, T. Dumitrica, R. Ballarini and W.W. Gerberich, “Dislocation morphology and nucleation within compressed Si nanospheres: A molecular dynamics study,” submitted , Computational Materials Science, 2011.
  • An Energy-Balance Criterion for Nanoindentation-Induced Single and Multiple Dislocation Events, (with W. M. Mook, W. A. Curtin, R. Mukherjee and S. L. Girshick), J. Appl. Mech. 73, pp. 327-334, (2006)
  • A new Picture of Plasticity, (with William Mook), Nature Materials, pp. 577-578 (August 2005)
  • In situ deformation of silicon nanospheres, (with Julia Deneen, William M. Mook, Andew Minor and C. Barry Carter), J. Mater. Sci. 41, pp. 4477-4483, (2006)
  • Plasticity responses in ultra-small confined cubes and films, (with M. J. Cordill, M. D. Chambers, M. S. Lund, D. M. Hallman, C. R. Perry, C. B. Carter, A. Bupat, U. Kortshagen), Acta Materialia, 54, pp. 4515-4523 (2006).
  • Indentation Fracture Toughness and Acoustic Energy Release in Tetrahedral Amorphous Carbon Diamond-like Films, (with J. M. Jungk, B. L. Boyce, T. E. Buchheit, T. A. Friedmann, D. Yang), Acta Materialia, 54 ( pp. 4043-4052 (2006)
  • Length Scales for the Fracture of Nanostructures (with J. Jungk and A.A. Volinsky), Intern. J. of Fracture (in press 2003).
  • An Approach to Dry Friction and Wear for Small Volumes (with N.I. Tymiak, D.E. Kramer, A. Daugela, J. Jungk and M. Li), Phil. Mag A 82(17/18), 3349 (2002).
  • Interfacial Toughness Measurements of Thin Metal Films (with A.A. Volinsky and N.R. Moody), Acta Mater. 50, 441 (2002).
  • Superhard Silicon Nanospheres (with W.M. Mook, C.R. Perrey, C.B. Carter, M.I. Baskes, R. Mukherjee, A. Gidwani, J. Heberlein, P.H. McMurry, and S.S. Girshick), J. Mech. Phys. Solids 51, 979 (2003).
  • Intepretation of Indentation Size Effects (with N.I. Tymiak, J.C. Grunlan, M.F. Horstemeyer and M.I. Baskes), J. Appl. Mech. 69, 433 (2002).


Daniel Sorensen

Eric Hintsala

Natalia Tymiak

Douglas Stauffer

Doug's picture Douglas is a fourth year graduate student in the Materials Science program. His research is concentrated on the mechanical properties of nanoscale materials, with a current focus on the electro-mechanical properties of metallic films and bulk Iridium single crystals. This is accomplished via in situ electrical contact measurement during nanoindentation. This is a collaboration with Hysitron, Inc which is also located here in the Twin Cities. He is also interested in tribology and wear of nanoscale materials as well as surface forces at small length scales.

Former recipient of the William Warren Gerberich Fellowship in the Solid Mechanics of Plasticity and Fracture

  1. W.W. Gerberich, J. Michler, W.M. Mook, R. Ghisleni, F. Ostlund, D.D. Stauffer, R. Ballarini, "Scale effects for strength, ductility, and toughness in “brittle” materials" Journal of Materials Research 24, (2009).
  2. A Coexistent View of Hydrogen Effects on Mechanical Behavior of Crystals: HELP and HEDE Effects of Hydrogen on Materials, Proc. of the 2008 International Hydrogen Conference pp 38-45. edited by B. Somerday, P. Sofronis, R. Jones, ASM International, Materials Park, OH (2009).
  3. C. Leighton, D.D. Stauffer, Q. Huang, Y. Ren, S. El-Khatib, M.A. Torija, J. Wu, J.W. Lynn, L. Wang, N.A. Frey, H. Srikanth, J.E. Davies, Kai Liu, J.F. Mitchell, "Coupled structural/magnetocrystalline anisotropy transitions in the doped perovskite cobaltite Pr1-xSrxCoO3" Physical Review B 79, 214420(1-7) (2009).
  4. W.W. Gerberich, D.D. Stauffer, A.R. Beaber, W.M. Mook, "Connectivity between plasticity and brittle fracture: an overview from nanoindentation studies," Proceedings of the Institution of Mechanical Engineers, Part N: Journal of Nanoengineering and Nanosystems 222, 1-18 (2009).
  5. D.D. Stauffer, C. Leighton, "Magnetic phase behavior of the ferrimagnetic doped cobaltite Nd1-xSrxCoO3" Physical Review B 70, 214414(1-7) (2004).

Aaron Beaber

Aaron's Picture Current research focuses on issues of nanocrystalline and nanocomposite deformation, particularly on the role of plasticity, phase transformations, and fracture events during the deformation of Si at small length scales. This includes the deposition of SiC-Si composites in a hybrid process combining chemical vapor deposition and nanoparticle impaction. Both SEM and TEM in situ nanoindentation are used to study the deformation process. Overall, the goal of my research is to synthesize materials with both high stiffness and fracture toughness for high wear applications and in doing so, develop a fundamental understanding of the nanocrystalline deformation.


  1. J.D. Nowak, A.R. Beaber, O. Ugurlu, W.W. Gerberich, O.L. Warren, "In-Situ Fracture of Silicon Nanoparticles," Microscopy and Microanalysis 15, 722-723 (2009).
  2. W.W. Gerberich, D.D. Stauffer, A.R. Beaber, W.M. Mook, "Connectivity between plasticity and brittle fracture: an overview from nanoindentation studies," Proceedings of the Institution of Mechanical Engineers, Part N: Journal of Nanoengineering and Nanosystems 222, 1-18 (2009).
  3. A.R. Beaber, J. Hafiz, J.V.R. Heberlein, W.W. Gerberich and S.L. Girshick, "Wear Behavior in SiC-TiX Multilayered Nanocomposite Coatings," Surface and Coatings Technology 203, 771-775, 2008.
  4. A. Beaber, L. Qi, J. Hafiz, W.W. Gerberich, S.L. Girshick, J.V.R. Heberlein and P.H. McMurry, "Nanostructured SiC by Chemical Vapor Deposition and Nanoparticle Impaction," Surface and Coatings Technology 202, 871-875 (2007).

Jeremy Dworshak

Lucas Hale

(co-advised with Prof. R. Ballarini)

Lucas's picture Lucas is studying the mechanical behavior of nanoscale structures using molecular dynamics with an interest in the yielding and hardening behavior in silicon nanoparticles, such as spheres, crystallites and cylinders, when subjected to a compressive loading. These simulations investigate how the observed behavior depends on particle size, orientation, temperature and atomic potential used. By comparing the simulations with experimental results on similar structures, a better understanding of the mechanical properties of these nanostructures should be established, along with insight on how to model them.


  1. L.M. Hale, X.W. Zhou, J.A. Zimmerman, N.R. Moody, R. Ballarini, W.W. Gerberich, "Molecular dynamics simulation of delamination of a stiff, body-centered-cubic crystalline film from a compliant Si substrate," Journal of Applied Physics 106, 083503(1-7) (2009).
  2. F. Ostlund, K. Rzepiejewska-Malyska, K. Leifer, L.M. Hale, Y. Tang, R. Ballarini, W.W. Gerberich, J. Michler, "Brittle-to-Ductile Transition in Uniaxial Compression of Silicon Pilars at Room Temperature," Advanced Functional Materials 19, 2439-2444 (2009).
  3. L. Hale, K.A. Gschneidner Jr., V.K. Pecharsky, Y. Mudryk, "Low temperature properties of some RIn3 compounds," Journal of Alloys and Compounds 472, 24-29 (2009).
  4. L. Hale Low temperature properties of some RIn3 compounds. Masters Thesis. Iowa State University, Ames IA (2007).
  5. K.A. Gschneidner Jr., A.O. Pecharsky, L. Hale, V.K. Pecharsky, "New 5K Magnetic Rare Earth Regenerator Intermetallic Compounds," Advances in Cryogenic Engineering. AIP Conference Proceedings ed. U. Balachandran 824, 19-26 (2006).
  6. K.A. Gschneidner Jr., A.O. Tsokel, L. Hale, V.K. Pecharsky, "Low Temperature Properties of Some Er-Rich Intermetallic Compounds," Advances in Cryogenic Engineering: Transactions of the International Cryogenic Materials Conference - ICMC. AIP Conference proceedings ed. U. Balachandran 711, 34-40 (2004).

Jenny Hwang

Jeremy Nichols

Dong-Bo Zhang

Other News

Professor Gerberich was listed as one of the top cited researchers in Materials Science on ISI Web of Knowledge's Highly Cited website.

A new article was published in the August 10, 2009 Advanced Functional Materials.

Brittle-to-Ductile Transition in Uniaxial Compression of Silicon Pillars at Room Temperature

Robust nanostructures for future devices will depend increasingly on their reliability. While great strides have been achieved for precisely evaluating electronic, magnetic, photonic, elasticity and strength properties, the same levels for fracture resistance have been lacking. Additionally, one of the self-limiting features of materials by computational design is the knowledge that the atomistic potential is an appropriate one. A key property in establishing both of these goals is an experimentally-determined effective surface energy or the work per unit fracture area. The difficulty with this property, which depends on extended defects such as dislocations, is measuring it accurately at the sub-micrometer scale. In this Full Paper the discovery of an interesting size effect in compression tests on silicon pillars with sub-micrometer diameters is presented: in uniaxial compression tests, pillars having a diameter exceeding a critical value develop cracks, whereas smaller pillars show ductility comparable to that of metals. The critical diameter is between 310 and 400 nm. To explain this transition a model based on dislocation shielding is proposed. For the first time, a quantitative method for evaluating the fracture toughness of such nanostructures is developed. This leads to the ability to propose plausible mechanisms for dislocation-mediated fracture behavior in such small volumes.
Fredrik Ostlund, Karolina Rzepiejewska-Malyska, Klaus Leifer, Lucas M. Hale, Yuye Tang, Roberto Ballarini, William W. Gerberich, Johann Michler, Ad. Func. Mater. 19 (2009) p2439.


Below: single crystal silicon sphere: TEM

Below: single crystal silicon nanosphere fractured in situ, TEM

Below: silicon pillar in TEM showing dark field images of dislocations