High performance Zintl phase TE materials with embedded ... · 24 A. Shakouri 1/4/2011....
Transcript of High performance Zintl phase TE materials with embedded ... · 24 A. Shakouri 1/4/2011....
Acknowledgement:NSF-DOE,
ONR, DARPA DSO
DOE Thermoelectric Applications Workshop, San Diego; 4 January 2011
Ali Shakouri and Zhixi BianEE, Univ. of California Santa CruzSusan KauzlarichChemistry, Univ. of California DavisIn collaboration withSabah Bux, Jean-Pierre Fleurial; JPLLon Bell; BSST, Amerigon
High performance Zintl phase TE materials with embedded nanoparticles
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Thermoelectric figure of merit, ZT
TSZTκσ2
=S: Seebeck coefficient
σ: Electrical conductivityκ: Thermal conductivity (e + phonon)
Power factor
Example: Si-doped (InGaAs)0.8(InAlAs)0.2
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Seebeck-conductivity trade-offEnergy
Density of States
Ef High doping
Doped Bulk Semiconductor
=> Potential to reach ZT~4-5 (with klattice~1W/mK)
Ef Low doping
Deg. Semiconductor/Metal + Energy Filter (Thermionic emission)
Ebarrier
Distance
Deg
. Sem
icon
duct
or/ M
etal
Barr
ier
Energy
Density of States
Ef
D. Vashaee and A. Shakouri, Phys. Rev. Lett. 92, 106103/1 (2004)
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ErAs Semi-metal Nanoparticles embedded in InGa(Al)As Semiconductor Matrix
Erbium is co-deposited at a growth rate which is a fixed fraction of the InGaAlAs growth rate (MBE growth)
Solubility limit is exceeded → islands are formed (2-3nm ErAs)
Josh Zide, Art Gossard and Chris Palmstrøm (UCSB and Delaware)
ErSb in In0.5Ga0.5Sb
TbAs in GaAs
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Electrical conductivity and Seebeck (theory/experiment)
M. Zebarjadi, et al., Appl. Phys. Lett. 2009J.-H. Bahk et al., Phys. Rev. B 2010 (Si-doped)J. Zide et al., J. Appl. Phys. 2010
Si-doped InGaAlAs
0.6% ErAs:InGaAlAs Si-doped InGaAlAs
0.6% ErAs:InGaAlAs
Electrical Conductivity Seebeck
The nanoparticle material is not optimized.
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0.08% ErAs
0.6%
Theory
Electron mobility in embedded nanoparticle material
Je-Hyeong Bahk et al. 2010
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Si-doped InGaAlAs
0.6% ErAs:InGaAlAs
UCSB, UCSC, UC Berkeley
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Largest measured ZT~1.33 at 800K
J. Zide et al. Journal of Applied Physics (Dec. 2010)
0
0.2
0.4
0.6
0.8
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1.2
1.4
1.6
300 400 500 600 700 800
ZT
T (K)
ErAs:InGaAlAs
n-InGaAlAs (control)
The majority of ZT enhancement is from thermal conductivity reduction.5% power factor enhancement at 800K.
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ErAs:InGa(Al)As thick growth approach
63 µm
SEM
Hong Lu, Art Gossard, UCSB
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Nanoparticle scattering optimizationPower factor, n-type InGaAs at 600K
~ 40% enhanced
Optimal: Q=1e, a=1.5 nmBulk alloy
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A. Shakouri 1/4/2011Silicide nanoparticles in SiGe
300K 3.4% nanoparticles
Silicon
Si0.5Ge0.5
GeNiSi2
ZT (300K) ~0.5
ZT (900K) ~1.8
Natalio Mingo et al. Nano Letters 2009
Predictions:
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1THz 10THz
Frequency contributions to thermal conductivity in presence of Iron silicide nanoparticles at 300K
Alloy1nm
3nm
10nm
30nm100nm
300nm
1µm30µm
300µm
Natalio Mingo 2009 (unpublished)
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A. Shakouri 1/4/2011Nanoparticles in Mg2SixSn1-x
Wang and Mingo Applied Physics Letter 2009
Synthesis and Characterization of Mg2Si/Si
Susan Kauzlarich’s GroupTanghong Yi
UC DavisAnd
Jean-Pierre Fleurial’s GroupSabah Bux
JPLPart of this work was performed at the Jet Propulsion Laboratory, California Institute
of Technology under contract with the National Aeronautics and Space Administration.
S. Kauzlarich 1/4/2011
Synthesis Goals
Develop non-toxic Zintl phase magnesium silicide alloys with embedded nanoparticles
Optimizing the matrix alloy composition and the nanoparticles for maximum thermoelectric figure-of-merit in 500K ~ 800K range
S. Kauzlarich 1/4/2011
Synthesis2MgH2 + (1+x)nano Si(Bi) Mg2Si/xSi(Bi)
(x = 0%, 1.25%, 2.5%, 5%)
Crystallite~ 50 nmParticle size ~200 nm
S. Kauzlarich 1/4/2011
Powder X-ray Diffraction
2.5 mol% Si5 mol% Si
S. Kauzlarich 1/4/2011
Transport properties
TY79: MgH2 + bulk Si = 2.25:1TY81: MgH2 + nano Si = 2.2:1TY95: MgH2 + nano Si = 2:1
TY101: MgH2 + nano Si = 1.95:1
S. Kauzlarich 1/4/2011
Sabah Bux and Jean-Pierre Fleurial (JPL)
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20
40
60
80
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250 450 650 850 1050
Ther
mal
Con
duct
ivity
(mW
/cm
K)
Temperature (K)
Undoped KidoTY79TY81TY95TY1012% Bi Kido
Tani and Kido, Physica B, 2005, 364, 218-224.
Transport propertiesS. Kauzlarich 1/4/2011
Sabah Bux and Jean-Pierre Fleurial (JPL)
0
20
40
60
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100
120
250 450 650 850
Latti
ce T
herm
al C
ondu
ctiv
ity (
mW
/cm
K)
Temperature (K)
Undoped Kido
TY79
TY81
TY95
TY101
2% Bi Kido
Nano-Si inclusions (1% to 5%)
Summary and Future Directions
Demonstrated n-type Mg2Si via a new synthetic method (MgH2 + Si) with naturally occurring Si nanoparticle inclusions.
Preliminary measurements of thermoelectric properties by JPL
Carrier concentration changes vs nanoinclusions needs to be studied
Further characterization of the pressed pellets is necessary to determine if the nanoinclusions are isolated and randomly distributed.
Further efforts are underway to reduce particle size along with optimization of carrier concentration.
S. Kauzlarich 1/4/2011
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PbTe/PbTeSe Quantum DotSuperlattices
Quaternary: ZT=2∆T=43.7 K
T.C. Harman, Science, 2002
Recent Advances in Thermoelectric Materials:Quantum Dot Superlattices (Science 2002), T. Harman et al.
Actual ZT ~1 (see e.g. Nanostructured
Thermoelectrics: Big EfficiencyGains from Small Features,
Vineis et al. Advanced Materials 2010)
Difficulty– Non-active barrier layers: Broido and
Reinecke PRB ‘01, Mahan, etc.
– Improvement “per conduction channel” is 40-60%- Kim et LundstromJ. Appl. Phys. 105, 034506 (2009)
– Dresselhaus et al. 1993
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Solar Cells (Efficiency+ Cost → $/W)
Cronin Vining, Nature Materials 2009
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1.E+02 1.E+04 1.E+06 1.E+08
Material cost of TE power generation system
Cross over
Air cooling (Aluminum heat sink)
Water cooling (microchannels)
Heat flux [W/m2]
$/m
2
2nd generation TE modules
3rd generation TE modules
K. Yazawa and A. Shakouri, International Mechanical Engineering Congress Nov. 2010
Current TE modules
Today’s TE power generation cost:
$1-2/W
Potential to bring this down to:
$0.1/W
See K. Yazawa’s presentation on
Wednesday
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Acknowledgement
Senior Researchers: Zhixi Bian, Kaz Yazawa, James Christofferson
Postdocs/Graduate Students: Je-Hyeong Bahk, Tela Favaloro, Phil
Jackson, Kerry Maize, Hiro Onishi, Paul Abumov, Oxana Pantchenko,
Amirkoushyar Ziabari, Bjorn Vermeersch, Gilles Pernot, Shila Alavi
Collaborators: John Bowers, Art Gossard, Chris Palmstrom (UCSB),
Tim Sands (Purdue), Rajeev Ram (MIT), Venky Narayanamurti
(Harvard), Arun Majumdar (Berkeley), Josh Zide (Delaware),
Lon Bell (BSST), Natalio Mingo (CEA/UCSC), Susan Kauzlarich (Davis),
Sabah Bux, Jean-Pierre Fleurial (NASA JPL)