Post on 13-Apr-2017
No impurity Ti (3 Å) Ti (6 Å) Ti (9 Å) Cu (3 Å) Cu (6Å) Cu (9 Å)
5 Å
10 Å
15 Å
20 Å
25 Å
35Å
45 Å
55 Å
ti(Å)
t s(Å)
Permanent magnet library
Ferroelectric library
Superconductor library
Ichiro TakeuchiUniversity of Maryland
Combinatorial Approach to Materials Discovery
• Introduction to the combinatorial approach:brief history, tools and strategies
• Integrated materials discovery engine
• Recent examples: combinatorial search of rare-earth-free permanent magnets; superconductors
Outline
University of MarylandTieren GaoSean FacklerKui JinR. Greene
SLACA. Mehta
US DOE, ONR, AFOSR
Support
Acknowledgement
Duke UniversityS. Curtarolo
Ames LabM. J. Kramer
NISTA. G. KusneM. Green
Chemical &EngineeringNews, August 2001
Combinatorial Libraries of Inorganic Materials
Luminescent materials libraries,Science 279, 1712 (1998)
Semiconductor gas sensor library, “electronic nose”,Appl. Phys. Lett. 83, 1255 (2003)
Magnetic shape memory alloy library,Nature Materials 2, 180 (2003)
Fabrication of libraries and spreadsCombinatorial PLD systems – metal oxides Combinatorial UHV sputtering system – metallic alloysCombinatorial multigun e-beam evaporator system – metal Combinatorial laser MBE – metal oxides
Rapid characterization toolsScanning SQUID microscopes – magnetic propertiesScanning microwave microscopes – resistive, magnetic, dielectricScanning X-ray microdiffractometerMagneto-optical Kerr effect (MOKE) system – magnetic propertiesScanning 4-point probe station – transportNovel device libraries incorporating MEMS, etc.
Major Facilities for CombinatorialMaterials Research at Maryland
Focus: Functional Thin Film Materials
Correlation between materials complexityand physical properties
HgNb3Ge
La2CuO4
YBa2Cu3O7
HgBa2CaCu3O7
Crit
ical
Tem
p. (K
)
306090
120150180210240
1Number of Elements2 3 4 5 6 7
1IA 2IIA 3IIIB 4IVB 5VB 6VIB 7VIIB 8VIII 9VIII 10VIII 11IB 12IIB 13IIIA 14IVA 15VA 16VIA 17VIIA 180H1 He2Li3
Be4
B5
C6
N7
O8
F9
Ne10
Na11
Mg12
Al13
Si14
P15
S16
Cl17
Ar18
K19
Ca20
Sc21
Ti22
V23
Cr24
Mn25
Fe26
Co27
Ni28
Cu29
Zn30
Ga31
Ge32
As33
Se34
Br35
Kr36
Rb37
Sr38
Y39
Zr40
Nb41
Mo42
Tc43
Ru44
Rh45
Pd46
Ag47
Cd48
In49
Sn50
Sb51
Te52
I53
Xe54
Cs55
Ba56
La57
Hf72
Ta73
W74
Re75
Os76
Ir77
Pt78
Au79
Hg80
Tl81
Pb82
Bi83
Po84
At85
Rn86
Fr87
Ra88
Ac89
Unq104
Unp105
Unh106
Uns107
Uno108
Une109
Uun110
Ce58
Pr59
Nd60
Pm61
Sm62
Eu63
Gd64
Tb65
Dy66
Ho67
Er68
Tm69
Yb70
Lu71
Th90
Pa91
U92
Np93
Pu94
Am95
Cm96
Bk97
Cf98
Es99
Fm100
Md101
No102
Lr103
Binary compounds have the form AB. (e. g., MgF, SiC, ZnO,…..)60 x 59 x different combinations: most are known.
Ternary compounds have the form ABC. (BaTiO, NiMnGa, HgCdTe,…)60 x 59 x 58 x different combinations: ~3 % of all possible known
Quaternary compounds have the form ABCD. (YBaCuO, AlNiCOFe,…)60 x 59 x 58 x 57 x different combinations: 0.01% of all possible known
Beyond??
How many different compounds are there?
Take 60 “useful” elements.
There are about~100,000 known inorganic compounds.
Quaternary Masks
A B
C ED
Quaternary Masking
Ba
Quaternary Masking: 1st mask, 1st position
Ca
Quaternary Masking: 1st mask, 2nd position
Sr
Quaternary Masking: 1st mask, 3rd position
Pb
Quaternary Masking: 1st mask, 4th position
BaPb
Sr Ca
Ba
Quaternary Masking: after 1st mask
BaPb
Sr Ca
BaZr
Zr
Zr
Zr
Quaternary Masking: 2nd mask, 1st position
BaPb
Sr Ca
BaTa
Ta
Ta
Ta
Quaternary Masking: 2nd mask, 2nd position
BaPb
Sr Ca
Ba
Nb
Nb Nb
Nb
Quaternary Masking: 2nd mask, 3rd position
BaPb
Sr Ca
BaTi
Ti Ti
Ti
Quaternary Masking: 2nd mask, 4th position
BaZrO3
CaNb2O6
CaTiO3
BaNb2O6
BaTiO3
CaTa2O6
CaZrO3
BaTa2O6PbTa2O6
PbZrO3PbTiO3
PbNb2O6
SrTiO3
SrNb2O6 SrTa2O6
SrZrO3
A B
C ED
# depositions: 4 x n# combinations: 4n
5 masks: 4 x 5 = 20 depo’s45 = 1024 samples
(Right) Luminescent image of the same library after thermally processed under UV excitation.
Science 279, 1712 (1998)
Library of luminescent materials made w/ quaternary masking
Various combinatorial experimental designs:
discrete libraries vs composition spreadsComposition A B
B
A
C
• Composition spreads allow continuous mapping of physical properties and phase boundaries
• Run to run variation in ordinary experiments is removed
Library synthesis under epitaxial growth conditions
F. Tsui (UNC)H. Koinuma, M. Lippmaa, T. Chikyow (COMET)
Materials are of the same quality as single composition depositions
Fabrication of epitaxial composition spread of oxides via laser MBE
Takeuchi et al., Applied Physics Letters 79, 4411 (2001)
Scanning Microwave Microscope:a rapid characterization tool
Originally developed for rapid screening of libraries of superconductors, dielectric materials, etc.
SampleTip
Coaxial ¼ resonator
x-y-z stage Motioncontroller
Computer
f0
Q
Microwave source
Review Article: Gao, et al., Measurement Science and Technology 16, 248 (2005)
-250
-200
-150
-100
-50
0
50
100
150
200
880 890 900 910 920 930 940 950 960 970
Magnetic field (Oe)
FMR
sign
al (a
rb. u
nit)
2.45 GHz
SrTiO3
BaTiO3
CaTiO3
500400
100
300
0
200
r
Different physical properties can be mapped using an existing microwave microscope
Dielectric constant mappingof a (Ba,Sr,Ca)TiO3 pseudo-ternary library at 1 GHz
Appl. Phys. Lett. 74, 1165 (1999)
Ferromagnetic resonance (FMR)signal taken at a spot
Dielectric property
Magnetic property(spin resonance)
composition plot
Mode/materials[reference]
Physical parameter/phenomenon
Spatialresolution
Dielectric [12-14] Complex dielectric constant
100 nm
Metal [13] Impedance/resistivity 100 nm
Non-lineardielectric [15,18]
Non-linear dielectric constant
1 nm
FMR Ferromagneticresonance
100 nm*
STM-ESR Electronspin resonance
Atomicresolution
Capabilities of Multiscale Microwave Microscope
Mapping of various physical properties can be obtained at macroscopic scale (~ 1 cm) down to the listed spatial resolution
Atomic resolution microwave microscope/STM
Tunneling current resonant f
HOPG
Au(111)Atomic resolution images obtained with STM disabled –
surface approachedusing microwave feedback
DC FieldMagnet
STM Tip Built‐In
Microwave Resonator(2.5 GHz)
(Lee et al., APL 97, 183111 (2010))
Composition Spreads of Ternary Metallic Alloy Systems
Co-sputtering scheme Ni
Mn
Al
3” spread wafer
Ni Al
Mn
Phase diagram
Composition is mapped using an electron probe (WDS)
RT Scanning SQUID microscope(Magma, Neocera)
SQUID assembly inside vacuum
leveling probe and scanning stage
Room temperature samples are measured
z-SQUID is used tomeasure Bz distribution
Tip-sample distance is typically 100~200 microns
15 20 25 30 35 40 45 50
60
50
40
30
20
col
ro
w
-2.50e+007 0.00e+000 2.50e+007
rho1_25_x
100-150 emu/cc
50-70 emu/cc30-40 emu/cc
10-20 emu/cc
Scanning SQUID image of a Ni-Mn-Ga spread wafer (room temperature)
0 13 25 38 50 63 75
80
60
40
20
0
col
ro
w
-2.50e+007 0.00e+000 2.50e+007
rho1_25
Mn rich
Ni rich Ni2Ga3 rich
Combinatorial Search of Ferromagnetic Materials
GaNi 0 1 2 3 4 5 6 7 8 9 10
Mn
50 100 150 200 250
M (emu/cc)
Ni2Ga3
Nature Materials 2, 180 (2003)
Rapid detection of shape memory alloy compositions by visual inspection
Composition spread deposited onmicromachined cantilever array
Film thickness ~0.5 m
Detection of martensitic phase transformation
Functional phase diagram of Ni-Mn-Ga
20 40 80
20
40
60
80
60
80
20
Mn
40
20 40 80
20
40
60
80
Ni
60
80
20
40
Ni2Ga3 Ga
Increasing transitiontemperature
Ferromagnetic regions
Most strongly magnetic
Martensites
Nature Materials 2, 180 (2003)
Integration of theory and high-throughput experiments
Step 2 Step 3Step 1
Integrated materials discovery engine
ExperimentalTrack
TheoreticalTrack
Step 2 Step 3Step 1
ExperimentalTrack
TheoreticalTrack
Advantages of this approach:
Predictions are sometimes “off” by stoichiometric variations.
Integration of theory and high-throughput experiments
Step 2 Step 3Step 1
ExperimentalTrack
TheoreticalTrack
Advantages of this approach:
Predictions are sometimes “off” by stoichiometric variations.
Large number of data points in combinatorial experiments suitable for building models.
Integration of theory and high-throughput experiments
Consortium of QM calculations
41api
http://aflowlib.org/Curtarolo,et al (Duke)
Step 2 Step 3Step 1
ExperimentalTrack
TheoreticalTrack
Example:Rare‐earth‐free permanent magnetsAPL 102, 022419 (2013);Scientific Reports 4, 6367 (2014)
Integration of theory and high-throughput experiments
Rare-earth (Nd, Dy, Sm, etc.)-free magnets are needed due to their fluctuating prices
Search for new permanent magnet materialsw/o rare-earth elements
The prices of many rare‐earth metals have increased by more than 10 fold in the past few years
Permanent magnets for: direct drive wind turbines
Current magnets: Nd‐Fe‐B, Sm‐Co
Advanced electric drive motors
History of development of permanent magnets
Best magnets contain rare-earth elements: Nd, Dy, Sm
Nd-Fe-B
Sm-Co
Year
How to design new permanent magnets• Need high energy product (BH)max
• Need high magnetization M ‐ need Fe and/or Co• Need high uniaxial anisotropy K – coercive field Hc
‐ e.g. NdFeB: 5 x 106 J/m3; SmCo5 2 x 107 J/m3
Paths to intrinsic anisotropy (without rare‐earth):• Modify FeCo: cubic to tetragonal, electronic structure• MnBi/MnAlX• Atomically ordered phase of FeNi
Modify/distort FeCo: add 3rd element X (d elements):spin‐orbit coupling; high anisotropy high coercive field‐> Make Fe‐Co‐X composition spreads
1852 C
2150 C 3412 C
2617 C
Melting points Melting points
1536 C 1495 C
Identification of composition with enhanced coercive field: Fe‐Co‐Mo Scientific Reports 4, 6367 (2014)
Composition with enhanced coercive field was identified
Magnetic hysteresis loop mapping of Fe‐Co‐Mo spread
Hc ~ 1.2 KOe(K ~ 30 eV/atom)
Hc mapping
Grouping of structures based on synchrotron diffraction
FeMo
Co
Calculated structures
Hc ~ 1.2 KOe(K ~ 30 eV/atom)
Hc mapping
Grouping of structures based on synchrotron diffraction
FeMo
Co
Identification of composition with enhanced coercive field: Fe‐Co‐MoIdentification of composition with enhanced coercive field: Fe‐Co‐Mo Scientific Reports 4, 6367 (2014)
Identified Fe8CoMo has a tetragonal structure; genetic algorithm and DFT give K values in agreement with experiment
Search for rare‐earth free permanent magnets
• High energy product (BH)max
‐ High magnetization M (Fe and/or Co)‐ High uniaxial anisotropy K – coercive field Hc
(NdFeB: 5 x 106 J/m3; SmCo5 2 x 107 J/m3)
Paths to intrinsic anisotropy (without rare‐earth):• Modify FeCo: cubic to tetragonal, electronic structure• MnBi/FeCo• Atomically ordered phase of FeNi
Optimizing MnBi/CoFe exchange coupled bilayers: soft layer thickness gradient on MnBi
BiMn annealing
MnBiCo
MnBiDeposition
of Co
Soft layer gradient 10 ‐ 0 nmglass or Si sub
MnBi thickness20 nm
(BH)max doubles from 12 to 25 MGOe by adding 3 nm of Co
(MG
Oe) 25 MGOe
Optimizing MnBi/CoFe exchange coupled bilayers: soft layer thickness gradient on MnBi
History of development of permanent magnets
Nd-Fe-B
Sm-Co
YearThis work: MnBi thin film/multilayers
Step 2 Step 3Step 1
ExperimentalTrack
TheoreticalTrack
Examples: Combinatrorial search of superconductivity in Fe‐BAPL Materials 1, 042101 (2013)
Integration of theory and high-throughput experiments
Targeting superconductors predicted by theory
Prediction:FeB4 is a superconductor with Tc ~ 15‐20 K
Fe-B phase diagram (1994)
FeB2FeB4
Not much is known in this region
Exploration of new superconductors: Fe-B composition spread
3” wafer
Fe rich B rich
16 spot 4‐terminal pogo pin arrays:
Cut wafers into 1 cm2 pieces and measure 16 spots at once
Color change tracks:composition change, crystallinity change, and metal to insulator transition
Fe-B composition spread: Fe-rich side, 16 spots on one 1 cm2 chip
Ch 113” wafer
more Bmore Fe
temperature
resistance
4.2 K 300 K
All metallic
Semiconducting to insulating
more Bmore Fe
temperature
resistance
4.2 K 300 K
Fe-B composition spread: B-rich side, 16 spots on one 1 cm2 chip
Ch 11Ch 3
Ch 13
Middle region:FeB2 – FeB4
more Bmore Fe
temperature
resistance
4.2 K 300 K
Fe-B composition spread: FeBx(x =2-4), 16 spots on one 1 cm2 chip
FeBx: we have found the superconductor
Susceptibilityshows diamagnetism
Bc2(T)= Bc2(0)[1-(T/Tc)2]/ [1+(T/Tc)2]
gives Bc2(0) = 2 T
-> Type II BCS superconductor
Partial R drop
~ 10 K?
Superconducting phase was detected in 2 spread wafers
Combinatorial Time Lapse:a day in the life of
a combinatorial materials scientist
Sean Fackler
Summary
Combinatorial experiments can be used to carry out effective mapping of large compositional phase spaces previously unexplored
This strategy has been incorporated into many technological areas; We have used this strategy to discover many new functional materials
Combinatorial strategy is the natural counterpart to the concerted theoretical efforts taking place within the Materials Genome Initiative
Review article: Green, et al.J. Appl. Phys. 113, 231101 (2013)