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Active Cooling Heat Source - UCSB MRSECseshadri/2012_286G/thermoelectrics.pdfThese ppt slides were...
Transcript of Active Cooling Heat Source - UCSB MRSECseshadri/2012_286G/thermoelectrics.pdfThese ppt slides were...
Materials 286 G: Structural Families of Functional Inorganic MaterialsRam Seshadri x6129 seshadri@mrlThese ppt slides were created by Professor M. A. Subramanian, Oregon State.
Class 12: Thermoelectrics
Peltier Effect
I+-
Active Cooling
Heat Rejection
np
Refrigeration Mode Power Generation Mode
I
Heat Source
Heat Sink
np
Seebeck Effect
“Refrigeration without movingparts and chemical refrigerant”
“Electricity from waste-heat”
Solid State materials are the key
Materials 286 G: Structural Families of Functional Inorganic MaterialsRam Seshadri x6129 seshadri@mrlThese ppt slides were created by Professor M. A. Subramanian, Oregon State.
66% 34%Energy Used
Electrical Energy
Automobile
Nuclear Power Plant
Waste Incinerator
Factory
Natural GasThermal Power Plant
PrimaryEnergy
RetrievalEnergy Loss/Waste Heat
Class 12: Thermoelectrics
Materials 286 G: Structural Families of Functional Inorganic MaterialsRam Seshadri x6129 seshadri@mrlThese ppt slides were created by Professor M. A. Subramanian, Oregon State.
Guest Editors: Tritt and Subramanian
March 2006
Thermoelectric Materials, Phenomena, and Applications: A Bird's Eye View: T. M. Tritt, M. A.Subramanian
Recent Developments in Bulk Thermoelectric Materials:G. S. Nolas, M. Kanatzidis
Properties of Nanostructured One-Dimensional and Composite: Thermoelectric Materials : A. M. Rao, X. Ji, and T. M. Tritt
March 2006
Class 12: Thermoelectrics
Materials 286 G: Structural Families of Functional Inorganic MaterialsRam Seshadri x6129 seshadri@mrl
10171018 1019 1020 1021
α σ
Carrier Concentration
Tota
l ΚZT
insu
lato
r
met
al
semiconductor
Contra-indicatedProperties
σ 2
ZT =α
(κe + κL)• T
Seebeck coefficientor thermopower
(ΔV/ΔT)
Electrical conductivity
Total thermal conductivity
σ α2α
σ
κ
ZTmax
κL
κe
No upper limit for ZT
Class 12: Thermoelectrics
Materials 286 G: Structural Families of Functional Inorganic MaterialsRam Seshadri x6129 seshadri@mrlThese ppt slides were created by Professor M. A. Subramanian, Oregon State.
+ +
Glass (amorphous)Very low
thermal conductivity
MetalHigh
electrical conductivity
Semiconductor High
Thermopower
Class 12: Thermoelectrics
Materials 286 G: Structural Families of Functional Inorganic MaterialsRam Seshadri x6129 seshadri@mrlThese ppt slides were created by Professor M. A. Subramanian, Oregon State.
25 450
1.0
- 75- 200Temperature oC
ZT
Bi2Te3 alloysPbTe alloys Si0.7Ge0.3
850
Narrow band gap semiconductors (increasing numerator)Elements of high atomic weight – e.g. Bi, Pb, Hg, Te (decreasing the denominator)
Class 12: Thermoelectrics
Materials 286 G: Structural Families of Functional Inorganic MaterialsRam Seshadri x6129 seshadri@mrlThese ppt slides were created by Professor M. A. Subramanian, Oregon State.
CsBi4Te6:Kanatzidis et al., Science, 287, 1024(2000)
AgPbmSbTe2+m:Kanatzidis et al., Science, 303, 818 (2004)
In0.2Co4Sb12:Subramanian et al., Chemistry of Materials, 18, 759 (2006)
Yb0.19Co4Sb12:Nolas, Tritt et al., J. Appl. Phys. 97, 113715 (2005).
In0.2Co4Sb12Ag
Class 12: Thermoelectrics
Materials 286 G: Structural Families of Functional Inorganic MaterialsRam Seshadri x6129 seshadri@mrlThese ppt slides were created by Professor M. A. Subramanian, Oregon State.
Co4Sb12 RxCo4Sb12 (R = Rare-earth, In)Large numeratorLarge DenominatorZT ~ 0.4 at 600K
Large numeratorSmall denominatorZT~ 1.3 at 600K
Subramanian et al., Chemistry of Materials, 18, 759 (2006)Nolas, Tritt et al., J. Appl. Phys. 97, 113715 (2005)Singh et al., Phys. Rev. B 53, 6273 (2003)
Class 12: Thermoelectrics
Materials 286 G: Structural Families of Functional Inorganic MaterialsRam Seshadri x6129 seshadri@mrl
Intermetallics with rare earths in intermediate valence statesYb 2+,3+ (4f13-4f14) ; Ce 3+,4+ (4f1-4f0)Large Density of States at the Fermi Level
- interaction between conduction electrons and partially localized 4f electrons leads to large α
- very large numerator (power factor) - large denominator (thermal conductivity) – low ZT
YbAl3 and CePd3
Class 12: Thermoelectrics
Materials 286 G: Structural Families of Functional Inorganic MaterialsRam Seshadri x6129 seshadri@mrl
PbSe
Bulk PbTe
•Electronic properties may be dramatically modified due to carrier confinement in nanostructures
•Thermoelectric power enhancement (rippling effect on DOS)
FEE
dEEd
eTkS B
==))((ln
3
22 σπ
PbSe
α
Class 12: Thermoelectrics
Materials 286 G: Structural Families of Functional Inorganic MaterialsRam Seshadri x6129 seshadri@mrl
AgPb18SbTe20Ag
Sb
Te
Pb
0
0.5
1
1.5
2
2.5
300 400 500 600 700 800
Latti
ce T
herm
al C
ondu
ctiv
ity (W
/mK
)
Temperature (K)
PbTe
LAST-18
Lattice thermal conductivity
Power factor still high
nanostructure
Kanatzidis et al Science, 2004, 303, 818
Class 12: Thermoelectrics
Materials 286 G: Structural Families of Functional Inorganic MaterialsRam Seshadri x6129 seshadri@mrlThese ppt slides were created by Professor M. A. Subramanian, Oregon State.
Pb Te Pb Te Pb Te Pb
Te Pb Te Pb Te Pb Te
Pb Te Sb Te Pb Te Pb
Te Ag Te Ag Te Pb Te
Pb
Te Pb
Te
Te
Sb
Pb
Te
Te
Pb
Pb
Te
Te
Pb
Ag Te Pb Te Pb Te Pb
Te Pb Te Pb Te Sb Te
Pb Te Pb Te Pb Te Pb
Te Ag Te Pb Te Pb Te
Pb
Te Pb
Te
Te
Pb
Pb
Te
Te
Sb
Pb
Te
Te
Pb
Dissociated state..unstable
Associated state..stable
Class 12: Thermoelectrics