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Combinatorial Approach to Materials Discovery

Combinatorial Approach to Materials Discovery. Ichiro Takeuchi Dept. of Materials Science and Engineering and Center for Superconductivity Research University of Maryland. Cover of Chemistry & Industry, October 1998. Making New Materials. 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12.

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Combinatorial Approach to Materials Discovery

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  1. Combinatorial Approach to Materials Discovery Ichiro Takeuchi Dept. of Materials Science and Engineering and Center for Superconductivity Research University of Maryland

  2. Cover of Chemistry & Industry, October 1998

  3. Making New Materials 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 IA IIA IIIB IVB VB VIB VIIB VIII VIII VIII IB IIB IIIA IVA VA VIA VIIA 0 H He 1 2 Li Be B C N O F Ne 3 4 5 6 7 8 9 10 Na Mg Al Si P S Cl Ar 11 12 13 14 15 16 17 18 K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I Xe 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 Cs Ba La Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn 55 56 57 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 Fr Ra Ac Unq Unp Unh Uns Uno Une Uun 87 88 89 104 105 106 107 108 109 110 Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu 58 59 60 61 62 63 64 65 66 67 68 69 70 71 Th Pa U Np Pu Am Cm Bk Cf Es Fm Md No Lr Searching for the right combination of elements For example, superconductor HgBa2CaCu2O7 90 91 92 93 94 95 96 97 98 99 100 101 102 103

  4. Parameters that Affect Properties of Materials • 1. Compositions 4. Presence of Defects • identity of components • stoichiometry • 2. Dopants 5. Microstructures • identity • concentration • 3. Processing Conditions • temperatures • pressures

  5. Synthesis of combinatorial libraries and composition spreads Materials diagnostics Rapid characterization and screening of physical properties

  6. Combinatorial Materials Research at the University of Maryland Focus: Electronic Thin Film Materials Fabrication of libraries and spreads Combinatorial PLD systems – metal oxide systems Combinatorial UHV sputtering system – metallic magnetic alloys Rapid characterization tools Scanning SQUID microscopes – magnetic materials Scanning microwave microscopes – ferroelectric/dielectric materials Scanning X-ray microdiffractometer – smart materials, phase mapping Novel device libraries incorporating MEMS, etc.

  7. Quaternary Masks B A C D E

  8. Quaternary Masking

  9. Quaternary Masking: 1st mask, 1st position Ba

  10. Quaternary Masking: 1st mask, 2nd position Ca

  11. Quaternary Masking: 1st mask, 3rd position Sr

  12. Quaternary Masking: 1st mask, 4th position Pb

  13. Quaternary Masking: after 1st mask Ba Ba Pb Sr Ca

  14. Quaternary Masking: 2nd mask, 1st position Zr Zr Ba Ba Pb Zr Zr Sr Ca

  15. Quaternary Masking: 2nd mask, 2nd position Ba Ba Pb Ta Ta Sr Ca Ta Ta

  16. Quaternary Masking: 2nd mask, 3rd position Ba Ba Pb Nb Nb Sr Ca Nb Nb

  17. Quaternary Masking: 2nd mask, 4th position Ti Ti Ba Ba Pb Ti Ti Sr Ca

  18. PbTiO3 PbZrO3 BaTiO3 BaZrO3 PbNb2O6 PbTa2O6 BaNb2O6 BaTa2O6 SrTiO3 SrZrO3 CaTiO3 CaZrO3 SrNb2O6 SrTa2O6 CaNb2O6 CaTa2O6

  19. # depositions: 4 x n # combinations: 4n 5 masks: 4 x 5 = 20 depo’s 45 = 1024 samples B A C D E

  20. Photograph of a 1” x 1”luminescent material library on Si after 20 quaternary depositions

  21. (Left) Luminescent image of the same library after thermally processed under UV excitation. Science 279, 1712 (1998)

  22. Discrete Libraries vs Composition Spreads • Composition spreads • Details of compositional • variation • Mapping of phase diagrams • BaTiO3-SrTiO3 • Magnetic metallic alloys • (Ferromagnetic shape memory • alloys) • Discrete libraries • Discrete (separated) samples • Various device libraries • Semiconductor gas sensor • libraries (electronic noses)

  23. Combinatorial Pulsed Laser Deposition Flange* x-y movable shutters/masks modular and compact 8” flange rotatable heater plate drive chain *US provisional patent filed

  24. Semiconductor Gas Sensors • Semiconductive metal oxides change their resistance in the presence of gases • Advantages: Inexpensive, fast response to gases, etc… • Problems: sensitivity, selectivity • Use combinatorial technique (dopant library) • An electronic nose is an array of many different gas sensors coupled to a multiplexed pattern recognition system

  25. Gas Sensor Library Layout 2 mm 2 mm SnO2 + In2O3+Pt (10%,2.5) In2O3+Pd (10%, 2.8%) ZnO+Pt (10%, 2.5%) ZnO+Pd (10%, 2.8%) Resistance ranges at room temp. 800W – 20MW In2O3 (10%) In2O3+Pd+Pt (10%, 2.5%, 2.5%) ZnO (10%) ZnO+Pd+Pt (10%,2.5%2.5%) Pt (2.5%) Pd (2.8%) WO3+Pt (50%,2.5) WO3+Pd (50%,2.8) Pd +Pt (2.5%, 2.5%) WO3 (50%) WO3+Pd +Pt (50%, 2.5%, 2.5%) 100%

  26. Discrete Gas Sensor Library 23 mm • Au pattern • 16 different elements • 500Å each • Deposition T= 500oC

  27. Response of different sensor elements to exposure to gases formaldehyde benzene formaldehyde chloroform Relative change in resistance 300 C 100 ppm in air Time (second)

  28. Fabrication of in-situ deposited composition spreads BaTiO3 BaTiO3 or SrTiO3 target Shutter Substrate Laser beam Moving shutter SrTiO3 Substrate (LaAlO3) at 800 C

  29. HRTEM Micrograph of a Single Composition Ba0.3Sr0.7TiO3 L. A. Bendersky, NIST

  30. minimum beam Spot 50mm x-y-z motorized stage Scanning x-ray microdiffractometer(Bruker) area detector (2q and c)

  31. Scanning x-ray microdiffraction Z 50 mm spot Substrate SrTiO3 Y BaTiO3 350 550 2 q angles

  32. 2q angle Scanning Diffraction Data ZnO (0002) of hexagonal Zn0.4Mg0.6O (0006) of Al2O3 (111) of cubic (200) (cubic) ZnO (0001) Al2O3 30 Zn0.4Mg0.6O 35 Composition change 40 45 2q c (0002) of (hexagonal) (200) of (cubic) 2q/c scan of Zn0.8Mg0.2O

  33. L l Coaxial ¼ resonator f0 Q Scanning Microwave Microscope Network analyzer Coupling loop For (Ba,Sr)TiO3 spread Tip Sample Motion x - y - z stage controller Rev. Sci. Inst., C. Gao et al., 69, 3846 (1998) Appl. Phys. Lett., I. Takeuchi et al., 71, 2026 (1997) Computer

  34. Scanning Microwave Microscope

  35. Dielectric const. vs. composition BaTiO3 x in Ba1-xSrxTiO3 SrTiO3

  36. Dielectric constant vs composition: temperature dependence 1000 room temp. 800 130 C 0.95 GHz 600 Dielectric constant 900 400 Dielectric const. 700 200 500 130 80 30 Temperature (0C) 0 0.0 0.2 0.4 0.6 0.8 1.0 BaTiO3 SrTiO3 x in Ba1-xSrxTiO3 Ba0.65Sr0.35TiO3 Appl. Phys. Lett. 79, 4411 (2001)

  37. Frequency dispersion (e1GHz-e5GHz)/e1GHz SrTiO3 BaTiO3 x in Ba1-xSrxTiO3

  38. Phonon soft mode and dielectric dispersion in (Ba,Sr)TiO3 films • Dielectric dispersion is caused by softening/hardening of the phonon soft mode. • The soft mode moves to the lower frequency range near Tc andresults in increased dispersion. • Compositions near Tc display largest dispersion.

  39. Magnetic Metallic Alloys • Permanent magnets, eg. FexNdyBz • Half metals with high spin polarization for spintronics devices • Ferromagnetic shape memory alloys • e.g. Ni2MnGa, Cu2MnGa • Scanning SQUID microscope is used to map • magnetic properties.

  40. Composition Spread of Metallic Alloys • UHV chamber -need to avoid oxygen and water • Magnetron co-sputtering Natural Composition Spread using UHV non-confocal co-sputtering

  41. x Combinatorial UHV Co-sputtering (Pbase1x10-9 Torr) Non-confocal (parallel) co-sputtering for creating natural ternary composition spreads. guns x distance between guns & substrate spread profile

  42. B A C Compositional Mapping B A-B-C composition spread A C A-B-C ternary phase diagram

  43. Mapping of Ni-Mn-Ga Ternary Phase Diagram Mn UHV co-sputtering of 3 targets From WDS analysis Mn Ni Ni2Ga3 i Ni-Mn-Ga composition spread Ni Ga

  44. Shape Memory Alloys Ferromagnetic Ferromagnetic ShapeMemory Alloys The material must • Be ferromagnetic • Be a shape memory alloy Rapid characterization • Scanning SQUID • Cantilever libraries • Scanning x-ray diffract. Example Ni2MnGa exhibits 6% strain in 1 kOe in bulk

  45. FMSMA 10 Co-ferrite 1 0.1 Magnetic field induced strain (%) Ni 0.01 Terfenol 0.001 1920 1940 1960 1980 2000 Year of Discovery History of Discovery: Magnetostrictive Materials Typical required field ~ kOe

  46. Mn Ni Ni2Ga3 Composition SpreadDeposition • Three targets: Ni, Mn, Ni2Ga3 • Substrate: Si • Thickness:  2500 Å • Insitu deposition w/physical mask • Lift off & annealed • Deposition or annealing temp 500 oC

  47. Scanning SQUID Microscope

  48. Image from a SQUID Scan 35 30 25 y position (mm) 20 15 10 5 40 30 20 10 x position (mm) -1100 -680 -260 160 580 1000 B field in nT

  49. 30-40 emu/cc 50-70 emu/cc 100-150 emu/cc 10-20 emu/cc Scanning SQUID image of a Ni-Ni2Ga3-Mn spread wafer Mn rich Ni2Ga3 rich Ni rich

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