Tamas Varga

Tamas Varga
Staff Member Title: 
Senior Research Scientist
Phone: 
(509) 371-6042
Contact Email: 
Tamas.Varga@pnnl.gov
Overview: 

Tamas Varga supports the x-ray diffraction (XRD) and x-ray computed tomography (XCT) user program at EMSL, maintains the XRD and XCT facilities in part, and develops his own research program utilizing EMSL's capabilities and possibilities for collaborative research. He performs XRD characterization of various types of samples (powder, thin film, etc.), XCT imaging of a range of materials (biological, geological, etc. samples), and conducts collaborative work in different projects including thin-film growth and characterization of new multiferroic materials, the energetic stability of various oxides and minerals, characterization of catalyst materials, plant and soil microtomography as well as x-ray capability development.

Details: 

Tamas Varga's past work experience includes graduate research on the synthesis and characterization of low and negative thermal expansion materials (GA Tech, Ph.D. Thesis, 2000-2005), thermochemistry of negative thermal expansion (NTE) materials and polymer-derived ceramics (PDCs), (UC Davis, postdoc, 2005-2007), high-pressure synthesis and characterization of complex magnetic oxides, superconductors, and multiferroics (Argonne National Lab, postdoc, 2007-2009), and more recently the synthesis and characterization if novel multiferroic thin films (PNNL, 2010-2015). Characterization work involved the extensive use of x-rays, neutrons, thermal analysis, electron microscopy, and physical property (conductivity, magnetism) characterization tools. He is a contributing editor to Phase Equilibria Diagrams by the American Ceramic Society. Tamas Varga was awarded two grants by petrochemical company TVK to support his undergraduate and, later, his postgraduate studies in Hungary.

Education: 
  • Ph.D. in Chemistry (Georgia Institute of Technology)
  • M.S. in Chemistry (University of Debrecen, Hungary)
  • M.S. in Economics (University of Miskolc, Hungary)
Awards & Honors: 

Awarded two PNNL grants (EMSL Intramural and PNNL LDRD) to study multiferroic oxide thin films.

Member of the American Chemical Society and the American Physical Society.

Research Interests: 

Tamas Varga's general research interests are structure-property relationships in solid oxides and the application of x-rays to crystal structure characterization as well as microstructural imaging. Tamas Varga is a solid state chemist, who has been conducting research on different complex solid oxides (negative thermal expansion (NTE) materials, multiferroics, magnetic materials), and polymer-derived ceramics (PDCs). During his research he has extensively used x-ray and neutron radiation to study the structure of matter. His work involved extreme environments, such as heat (solid state synthesis, high-temperature calorimetry, etc.), and pressure (high-pressure synthesis) for materials synthesis and characterization. His most important accomplishments are (i) his contribution to the understanding of phase transformations in NTE materials, (ii) his findings about the energetics of NTE and PDC materials, as well as (iii) his work on titanates with potential multiferroic properties. He also did pioneering work involving the simultaneous application of in situ synchrotron x-ray diffraction and x-ray absorption spectroscopy for materials studies.

Capabilities: 
Spectroscopy and Diffraction
Key Research Areas: 
x-ray diffraction (XRD)
thin-film growth and characterization of new multiferroic materials
thermodynamics of various oxides and minerals
characterization of catalyst materials
x-ray capability development
Instrument(s): 
Epitaxial Thin Film XRD
Microbeam XRD
X-ray Computed Tomography

Publications

2016

  • L Zhang, W Jiang, AC Dissanayake, T Varga, J Zhang, Z Zhu, D Hu, H Wang, CH Henager, T Wang. 2016. "Grain growth of nanocrystalline 3C-SiC under Au ion irradiation at elevated temperatures." Journal of Physics D. Applied Physics 49(3)035304. 10.1088/0022-3727/49/3/035304
  • S Prodinger, VRSes Vemuri, T Varga, BPeter McGrail, RK Motkuri, MA Derewinski. 2016. "Impact of chabazite SSZ-13 textural properties and chemical composition on CO2 adsorption applications." New Journal of Chemistry 40(5)4375-4385. 10.1039/C5NJ03205A
  • DI Kaplan, RK Kukkadapu, JC Seaman, BW Arey, A Dohnalkova, S Buttner, D Li, T Varga, KG Scheckel, PR Jaffe. 2016. "Iron Mineralogy and Uranium-Binding Environment in the Rhizosphere of a Wetland Soil." Science of Total Environment 569-57053-64. 10.1016/j.scitotenv.2016.06.120
  • S Kabilan, HB Jung, AP Kuprat, ANR Beck, T Varga, CA Fernandez, W Um. 2016. "Numerical Simulation of Permeability Change in Wellbore Cement Fractures after Geomechanical Stress and Geochemical Reactions Using X-ray Computed Tomography Imaging.." Environmental Science & Technology 50(12)6180–6188. 10.1021/acs.est.6b00159
  • TG Levitskaia, S Chatterjee, N Pence, J Romero, T Varga, MH Engelhard, Y Du, L Kovarik, BW Arey, ME Bowden, ED Walter. 2016. "Inorganic Tin Aluminophosphate Nanocomposite for Reductive Separation of Pertechnetate." Environmental Science: Nano 3(2)1003-1013. 10.1039/C6EN00130K
  • Y Choi, X Jiang, W Bi, P Lapa, RK Chouhan, D Paudyal, T Varga, D Popov, J Cui, D Haskel, JS Jiang. 2016. "Element-resolved magnetism across the temperature- and pressure-induced spin reorientation in MnBi." Physical Review B 94(18)184433. 10.1103/PhysRevB.94.184433
  • CA Fernandez, H Shao, A Bonneville, T Varga, L Zhong. 2016. "On the Versatility of Rheoreversible, Stimuli-responsive Hydraulic-Fracturing Fluids for Enhanced Geothermal Systems: Effect of Reservoir pH."
  • N Suresh, SA Stephens, L Adams, ANR Beck, AL McKinney, T Varga. 2016. "Extracting Metrics For Three-dimensional Root Systems: Volume And Surface Analysis From In-soil X-ray Computed Tomography Data." Journal of Visualized Experiments 110Article No. e53788. 10.3791/53788

2015

  • ES Ilton, TC Droubay, AM Chaka, L Kovarik, T Varga, BW Arey, SN Kerisit. 2015. "Epitaxial single-crystal thin films of MnxTi1-xO2-δ grown on (rutile)TiO2 substrates with pulsed laser deposition: Experiment and theory." Surface Science 632185-194. 10.1016/j.susc.2014.10.013
  • T Varga, TC Droubay, ME Bowden, SA Stephens, S Manandhar, V Shutthanandan, RJ Colby, D Hu, WA Shelton, SA Chambers. 2015. "Strain-dependence Of The Structure And Ferroic Properties Of Epitaxial Ni-1 (-) Ti-x(1) (-) O-y(3) Thin Films Grown On Sapphire Substrates." Thin Solid Films 578113-123. 10.1016/j.tsf.2015.02.016
  • BT Flynn, H Zhang, V Shutthanandan, T Varga, RJ Colby, RP Oleksak, S Manandhar, MH Engelhard, SA Chambers, MA Henderson, GS Herman, S Thevuthasan. 2015. "Growth and Surface Modification of LaFeO3 Thin Films Induced By Reductive Annealing." Applied Surface Science 330309-315. 10.1016/j.apsusc.2015.01.028
  • GR Kulkarni, MI Nandasiri, A Zelenyuk, J Beranek, N Madaan, A Devaraj, V Shutthanandan, S Thevuthasan, T Varga. 2015. "Effects Of Crystallographic Properties On The Ice Nucleation Properties Of Volcanic Ash Particles." Geophysical Research Letters 42(8)3048-3055. 10.1002/2015GL063270
  • HB Jung, KC Carroll, S Kabilan, DJ Heldebrant, DW Hoyt, L Zhong, T Varga, SA Stephens, L Adams, A Bonneville, AP Kuprat, CA Fernandez. 2015. "Stimuli-Responsive/Rheoreversible Hydraulic Fracturing Fluids as a Greener Alternative to Support Geothermal and Fossil Energy Production." Green Chemistry 17(5)2799-2812. 10.1039/c4gc01917b
  • W Jiang, CH Henager, T Varga, HJ Jung, NR Overman, C Zhang, J Gou. 2015. "Diffusion of Ag, Au and Cs implants in MAX phase Ti3SiC2." Journal of Nuclear Materials 462310-320. 10.1016/j.jnucmat.2015.04.002
  • T Varga, TC Droubay, ME Bowden, L Kovarik, D Hu, SA Chambers. 2015. "Strain-dependence Of The Structure And Ferroic Properties Of Epitaxial NiTiO3 Thin Films Grown On Different Substrates." Advances in Condensed Matter Physics 2015Art. No. 493045. 10.1155/2015/493045
  • G Li, T Varga, P Yan, Z Wang, CM Wang, SA Chambers, Y Du. 2015. "Crystallographic Dependence of Photocatalytic Activity of WO3 Thin Films Prepared by Molecular Beam Epitaxy." Physical Chemistry Chemical Physics. PCCP 17(23)15119-15123. 10.1039/c5cp01344e
  • Y Liu, C Liu, RK Kukkadapu, JP McKinley, JM Zachara, AE Plymale, MD Miller, T Varga, CT Resch. 2015. "99Tc(VII) Retardation, Reduction, and Redox Rate Scaling in Naturally Reduced Sediments." Environmental Science & Technology 49(22)13403-13412. 10.1021/acs.est.5b03273
  • H Shao, S Kabilan, SA Stephens, N Suresh, ANR Beck, T Varga, PF Martin, AP Kuprat, HB Jung, W Um, A Bonneville, DJ Heldebrant, KC Carroll, J Moore, CA Fernandez. 2015. "Environmentally Friendly, Rheoreversible, Hydraulic-fracturing Fluids for Enhanced Geothermal Systems." Geothermics 5822-31. 10.1016/j.geothermics.2015.07.010

2014

  • HB Jung, S Kabilan, JP Carson, AP Kuprat, W Um, PF Martin, ME Dahl, TA Kafentzis, T Varga, SA Stephens, BW Arey, KC Carroll, A Bonneville, CA Fernandez. 2014. "Wellbore cement fracture evolution at the cement–basalt caprock interface during geologic carbon sequestration." Applied Geochemistry 471-16. 10.1016/j.apgeochem.2014.04.010
  • W Jiang, JA Sundararajan, T Varga, ME Bowden, Y Qiang, JS McCloy, CH Henager, RO Montgomery. 2014. "In-situ Study of Nanostructure and Electrical Resistance of Nanocluster Films Irradiated with Ion Beams." Advanced Functional Materials 24(39)6210-6218. 10.1002/adfm.201400553
  • W Jiang, L Kovarik, Z Zhu, T Varga, MH Engelhard, ME Bowden, TM Nenoff, T Garino. 2014. "Microstructure and Cs Behavior of Ba-Doped Aluminosilicate Pollucite Irradiated with F+ Ions." Journal of Physical Chemistry C 118(31)18160-18169. 10.1021/jp5045223
  • Y Du, M Gu, T Varga, CM Wang, ME Bowden, SA Chambers. 2014. "Strain Accommodation By Facile WO6 Octahedral Distortion and Tilting During WO3 Heteroepitaxy on SrTiO3(001)." ACS Applied Materials & Interfaces 6(16)14253-14258. 10.1021/am5035686
  • GM Bowers, DW Hoyt, SD Burton, BO Ferguson, T Varga, RJ Kirkpatrick. 2014. "In Situ 13C and 23Na Magic Angle Spinning NMR Investigation of Supercritical CO2 Incorporation in Smectite-Natural Organic Matter Composites." Journal of Physical Chemistry C 118(7)3564-3573. 10.1021/jp410535d
  • Y Du, H Zhang, T Varga, SA Chambers. 2014. "Reflection High-Energy Electron Diffraction Beam-Induced Structural and Property Changes on WO3 Thin Films." Applied Physics Letters 105(5)051606. 10.1063/1.4892810
  • JH Kwak, T Varga, CHF Peden, F Gao, JC Hanson, J Szanyi. 2014. "Following the movement of Cu ions in a SSZ-13 zeolite during dehydration, reduction and adsorption: a combined in situ TP-XRD, XANES/DRIFTS study." Journal of Catalysis 314(1)83-93. 10.1016/j.jcat.2014.03.003
  • AG Perez-Bergquist, Y Zhang, T Varga, S Moll, F Namavar, WJ Weber. 2014. "Temperature-dependent Void Formation and Growth At Ion-irradiated Nanocrystalline CeO2–Si Interfaces." Nuclear Instruments and Methods in Physics Research. Section B, Beam Interactions with Materials and Atoms 32566-72. 10.1016/j.nimb.2014.02.012
  • Y Zhang, T Varga, M Ishimaru, PD Edmondson, H Xue, P Liu, S Moll, F Namavar, CM Hardiman, S Shannon, WJ Weber. 2014. "Competing Effects Of Electronic And Nuclear Energy Loss On Microstructural Evolution In Ionic-covalent Materials." Nuclear Instruments and Methods in Physics Research. Section B, Beam Interactions with Materials and Atoms 32733-43. 10.1016/j.nimb.2013.10.095
  • Y Zhang, DS Aidhy, T Varga, S Moll, PD Edmondson, F Namavar, K Jin, CN Ostrouchov, WJ Weber. 2014. "The Effect of Eectronic Energy Loss on Irradiation-Induced Grain Growth in Nanocrystalline Oxides." Physical Chemistry Chemical Physics. PCCP 16(17)8051-8059. 10.1039/c4cp00392f
  • Y Zhang, DS Aidhy, T Varga, S Moll, PD Edmondson, F Namavar, K Jin, CN Ostrouchov, WJ Weber. 2014. "The Effect Of Electronic Energy Loss On Irradiation-induced Grain Growth In Nanocrystalline Oxides." Physical Chemistry Chemical Physics. PCCP 16(17)8051-8059. 10.1039/c4cp00392f
  • P Munusamy, SP Sanghavi, T Varga, S Thevuthasan. 2014. "Silica Supported Ceria Nanoparticles: A Hybrid Nanostructure To Increase Stability And Surface Reactivity Of Nano-crystalline Ceria." RSC Advances 4(17)8421-8430. 10.1039/c3ra44345k
  • A Bonneville, HB Jung, H Shao, S Kabilan, W Um, KC Carroll, T Varga, N Suresh, SA Stephens, CA Fernandez. 2014. "Stimuli Responsive/Rheoreversible Hydraulic Fracturing Fluids for Enhanced Geothermal Energy Production (Part II)."

2013

  • T Varga, TC Droubay, ME Bowden, RJ Colby, S Manandhar, V Shutthanandan, D Hu, BC Kabius, E Apra, WA Shelton, SA Chambers. 2013. "Coexistence of Weak Ferromagnetism and Polar Lattice Distortion in Epitaxial NiTiO3 thin films of the LiNbO3-Type Structure." Journal of Vacuum Science and Technology B--Microelectronics and Nanometer Structures 31(3)Article No. 030603. 10.1116/1.4801664
  • P Sushko, L Qiao, ME Bowden, T Varga, GJ Exarhos, FK Urban, III, D Barton, SA Chambers. 2013. "Multiband Optical Absorption Controlled by Lattice Strain in Thin-Film LaCrO3." Physical Review Letters 110(7)077401. 10.1103/PhysRevLett.110.077401
  • L Qiao, H Zhang, ME Bowden, T Varga, V Shutthanandan, RJ Colby, Y Du, BC Kabius, PV Sushko, MD Biegalski, SA Chambers. 2013. "The Impacts of Cation Stoichiometry and Substrate Surface Quality on Nucleation, Structure, Defect Formation, and Intermixing in Complex Oxide Heteroepitaxy–LaCrO3 on SrTiO3(001)." Advanced Functional Materials 23(23)2953–2963. 10.1002/adfm.201202655
  • L Qiao, HY Xiao, SM Heald, ME Bowden, T Varga, GJ Exarhos, MD Biegalski, IN Ivanov, WJ Weber, TC Droubay, SA Chambers. 2013. "The impact of crystal symmetry on the electronic structure and functional properties of complex lanthanum chromium oxides." Journal of Materials Chemistry C 1(30)4527-4535. 10.1039/C3TC30883A
  • W Jiang, Z Zhu, T Varga, ME Bowden, S Manandhar, TJ Roosendaal, SY Hu, CH Henager, RJ Kurtz, Y Wang. 2013. "PROPERTIES OF DEFECTS AND IMPLANTS IN Mg+ IMPLANTED SILICON CARBIDE ."
  • T Portet, PN Holmes, ME Bowden, SA Stephens, T Varga, SL Keller. 2013. "Petal Thicknesses and Shape Transformations in Blooming Lilies." Biophysical Journal 104(2 Supplement 1)493A-493A. 10.1016/j.bpj.2012.11.2717
  • S Vilayur Ganapathy, A Devaraj, RJ Colby, A Pandey, T Varga, V Shutthanandan, S Manandhar, PZ El-Khoury, AN Kayani, WP Hess, S Thevuthasan. 2013. "Subsurface Synthesis and Characterization of Ag Nanoparticles Embedded in MgO." Nanotechnology 24(9)Article No. 095707. 10.1088/0957-4484/24/9/095707
  • JE Jaffe, TC Kaspar, TC Droubay, T Varga. 2013. "Band offsets for mismatched interfaces: The special case of ZnO on CdTe (001)." Journal of Vacuum Science and Technology A--Vacuum, Surfaces and Films 31(6)061102. 10.1116/1.4816951
  • JS McCloy, W Jiang, TC Droubay, T Varga, L Kovarik, JA Sundararajan, M Kaur, Y Qiang, E Burks, K Liu. 2013. "Ion irradiation of Fe-Fe oxide core-shell nanocluster films: Effect of interface on stability of magnetic properties." Journal of Applied Physics 114(8)083903:1-9. 10.1063/1.4818309
  • KO Albrecht, VAlexandra Glezakou, RJ Rousseau, MH Engelhard, T Varga, RJ Colby, JE Jaffe, XS Li, D Mei, CF Windisch, SM Kathmann, TL Lemmon, MJ Gray, TR Hart, BL Thompson, MA Gerber. 2013. "Rh-Based Mixed Alcohol Synthesis Catalysts: Characterization and Computational Report."
  • W Jiang, R Devanathan, CJ Sundgren, M Ishimaru, K Sato, T Varga, S Manandhar, A Benyagoub. 2013. "Ion Tracks and Microstructures in Barium Titanate Irradiated with Swift Heavy Ions: A Combined Experimental and Computational Study." Acta Materialia 61(20)7904-7916. 10.1016/j.actamat.2013.09.029
  • S Vilayur Ganapathy, MI Nandasiri, AG Joly, PZ El-Khoury, T Varga, GW Coffey, B Schwenzer, A Pandey, AN Kayani, WP Hess, S Thevuthasan. 2013. "Silver nanorod arrays for photocathode applications." Applied Physics Letters 103(16)Article No. 161112. 10.1063/1.4825262

2012

  • TC Kaspar, ME Bowden, T Varga, CM Wang, V Shutthanandan, AG Joly, BD Wirth, RJ Kurtz. 2012. "Structural characterization of epitaxial CrxMo1−x alloy thin films." Journal of Physics. Condensed Matter 24(9)095001. 10.1088/0953-8984/24/9/095001
  • T Varga, TC Droubay, ME Bowden, P Nachimuthu, V Shutthanandan, TB Bolin, WA Shelton, SA Chambers. 2012. "Epitaxial growth of NiTiO3 with a distorted ilmenite structure." Thin Solid Films 520(17)5534-5541. 10.1016/j.tsf.2012.04.060
  • N Joy, MI Nandasiri, PH Rogers, W Jiang, T Varga, SVN T Kuchibhatla, S Thevuthasan, MA Carpenter. 2012. "Selective Plasmonic Gas Sensing: H2, NO2, and CO Spectral Discrimination by a Single Au-CeO2 Nanocomposite Film." Analytical Chemistry 84(11)5025-5034. 10.1021/ac3006846
  • MS Rajachidambaram, T Varga, L Kovarik, RP Sanghavi, V Shutthanandan, S Thevuthasan, S Han, C Chang, GS Herman. 2012. "Formation of zinc oxide films using submicron zinc particle dispersions." Journal of Vacuum Science and Technology B--Microelectronics and Nanometer Structures 30(4)Article No. 041805. 10.1116/1.4731255
  • JS Rajachidambaram, SP Sanghavi, P Nachimuthu, V Shutthanandan, T Varga, BT Flynn, S Thevuthasan, GS Herman. 2012. "Characterization of Amorphous Zinc Tin Oxide Semiconductors." Journal of Materials Research 27(17)2309-2317. 10.1557/jmr.2012.170
  • PD Edmondson, Y Zhang, SJ Moll, T Varga, F Namavar, WJ Weber. 2012. "Anomalous grain growth in the surface region of a nanocrystalline CeO2 film under low-temperature heavy ion irradiation." Physical Review. B, Condensed Matter and Materials Physics 85(21)Article No. 214113. 10.1103/PhysRevB.85.214113
  • Y Zhang, M Ishimaru, T Varga, T Oda, CM Hardiman, H Xue, Y Katoh, S Shannon, WJ Weber. 2012. "Nanoscale Engineering Of Radiation Tolerant Silicon Carbide." Physical Chemistry Chemical Physics. PCCP 14(38)13429-13436. 10.1039/C2CP42342A

2011

  • L Qiao, TC Droubay, T Varga, ME Bowden, V Shutthanandan, Z Zhu, TC Kaspar, SA Chambers. 2011. "Epitaxial growth, structure and intermixing at the LaAlO3/SrTiO3 interface as the film stoichiometry is varied." Physical Review. B, Condensed Matter and Materials Physics 83(8)085408. 10.1103/PhysRevB.83.085408
  • Y Du, DJ Kim, T Varga, Z Wang, J Szanyi, I Lyubinetsky. 2011. "Formation of single-phase BaO nanoclusters." Thin Solid Films 519(16)5335-5338. 10.1016/j.tsf.2011.02.032
  • RP Sanghavi, MI Nandasiri, SVN T Kuchibhatla, W Jiang, T Varga, P Nachimuthu, MH Engelhard, V Shutthanandan, S Thevuthasan, AN Kayani, S Prasad. 2011. "Thickness Dependency of Thin Film Samaria Doped Ceria for Oxygen Sensing ." IEEE Sensors Journal 11(1)217-224. 10.1109/JSEN.2010.2050766
  • MI Nandasiri, P Nachimuthu, T Varga, V Shutthanandan, W Jiang, SVN T Kuchibhatla, S Thevuthasan, S Seal, AN Kayani. 2011. "Influence of growth rate on the epitaxial orientation and crystalline quality of CeO2 thin films grown on Al2O3(0001)." Journal of Applied Physics 109(1)013525:1-7. 10.1063/1.3525558
  • DP Jaisi, RK Kukkadapu, LM Stout, T Varga, RE Blake. 2011. "Biotic and abiotic pathways of phosphorus cycling in minerals and sediments: insights from oxygen isotopes in phosphate." Environmental Science & Technology 45(15)6254-6261. 10.1021/es200456e
  • Y Zhang, PD Edmondson, T Varga, SJ Moll, F Namavar, C Lan, WJ Weber. 2011. "Structural Modification of Nanocrystalline Ceria by Ion Beams." Physical Chemistry Chemical Physics. PCCP 13(25)11946-11950. 10.1039/c1cp21335k

2010

  • JE Jaffe, TC Kaspar, TC Droubay, T Varga, ME Bowden, GJ Exarhos. 2010. "Electronic and defect structure of CuSCN." Journal of Physical Chemistry C 114(19)9111-9117. 10.1021/jp101586q
  • T Varga, J Mitchell, J Wang, L Arnold, BH Toby, C Malliakas. 2010. "High-pressure Synthesis, Crystal and Electronic Structures of a New Scandium Tungstate, Sc₀․₆₇WO₄." Journal of Solid State Chemistry 183(7)1567-1573. 10.1016/j.jssc.2010.04.039

2009

  • T Varga, A Wilkinson. 2009. "Zirconium coordination change upon the pressure-induced amorphization of cubic ZrW2O8 and ZrMo2O8." Physical Review. B, Condensed Matter 79(22)Article No. 224119. 10.1103/PhysRevB.79.224119