direct energy conversion: chemistry, physics, materials science · pdf filemercouri g...

Mercouri G Kanatzidis

Direct Energy Conversion: Chemistry, Physics, Materials Science and Thermoelectrics

MURIKANATZIDIS

MSU, CHEMISTRYSolid State ChemistrySynthesis, Discovery

KANATZIDISMSU, CHEMISTRY

Solid State ChemistrySynthesis, Discovery

CTIRAD UHERUniv of Michigan

PhysicsMeasurements

CTIRAD UHERUniv of Michigan

PhysicsMeasurements

TIM HOGANMSU, E. ENGINEERINGMeasurements, Devices

S. D. MAHANTIMSU, PHYSICS

Theory

HAROLD SCHOCKMSU, Mechanical

EngineeringApplications

ELDON CASEMSU, Mechanical

EngineeringMetallurgy

American Physical Society Meeting, Baltimore March 2006

Heat to Electrical Energy DirectlyUp to 20% conversion efficiency with right materials

Schock grouphttp://www.dts-generator.com/

Thermoelectric applicationsWaste heat recovery • Automobiles• Over the road trucks• Utilities• Chemical plants

Space powerRemote Power GenerationSolar energyGeothermal power generationDirect nuclear to electrical

U.S. Energy Flow, 1999

web site: www.eia.doe.gov

Given that ~60% of energy becomes waste heat, even a 10% capture and conversionto useful forms can have huge impact on overall energy utilization

How does it work?http://www.designinsite.dk

TE devices have no moving parts, no noise, reliable

Figure of Merit

ZT =σ ⋅S2

κ total

•T

σ ⋅S2Power factor

Total thermal conductivity

electrical conductivity thermopower

ZT =σ ⋅S2

κ total

•T

σ ⋅S2Power factor

Total thermal conductivity

electrical conductivity thermopower

0

0.05

0.1

0.15

0.2

0.25

0 0.5 1 1.5 2 2.5 3

η

ZTavg

δ = 0.0δ = 0.1

δ = 1.1

0

0.05

0.1

0.15

0.2

0.25

0 0.5 1 1.5 2 2.5 3

η

ZTavg

δ = 0.0δ = 0.1

δ = 1.1

δ=Rc/RFor Th = 800K

Tc = 300K

Today’s situationThe most efficient materials today for power generation: PbTe and TAGS (TeSbGeAg alloy)The most efficient material for cooling Bi2Te3PbTe: ZT~0.8 at 800 K (n-type)TAGS: ZT~1.2 700 K (p-type)Bi2Te3-xSex: ZT~1 at 300 KFurther improvements are needed.New materials needed

PbTePbSe 20 nm dot

Hicks LD, Dresselhaus MS Phys. Rev. B 47 1993 (24): 16631

Quantum Dot Layers in thin MBE-grown PbSe/PbTesuperlattices (Harman et al, ZT~3)

Some promising systems under investigation

half-Heusler alloys (ZrNiSn)Zn4Sb3ClathratesSkutterudites (CoSb3)Bulk nanocomposites based on PbTe Bulk nanocomposites based on Si-GeAgSbTe2/PbTe, NaSbTe2/PbTe

See March 2006 issue of MRS Bulletin

( )2/1

2/3

max+∝ r

latt

z

yx

em

mmT

Zκ

τγ

ZT and Electronic Structure

m= effective massτ=scattering timer= scattering parameterκlatt= lattice thermal conductivityT = temperatureγ= band degeneracy

Large γ comes with(a) high symmetry e.g. rhombohedral, cubic(b) off-center band extrema

Isotropic structure

Anisotropic structure

k

E

k

E

k

Ef

For acoustic phonon scatteringr=-1/2

Complex electronic structure

Selection criteria for candidate materials

Narrow band-gap semiconductorsHeavy elements

High µ, low κLarge unit cell, complex structure

low κHighly anisotropic or highly symmetric…Complex compositions

low κ, complex electronic structure

A2Q + PbQ + M2Q3 –––––> (A2Q)n(PbQ)m(M2Q3)p

Chemistry as a source of materials

A2Q

PbQBi2Q3

A=Ag, K, Rb, CsM=Sb, BiQ=Se, Te

β-K2Bi8Se13

Rb0.5Bi1.83Te3

Pb5Bi6Se14

A1+xPb4-2xBi7+xSe15

APb2Bi3Te7

Pb6Bi2Se9 Pb5Bi12Se23

Map generates target compounds

CsBi4Te6

Investigating the System:

Phases shownare promising new TEMaterials

Cubic materialsABmMQ2+m

Our first contact with cubic AgPbmSbTe2+m

AgBi3S5, KPbBi9Se13, KPb4Sb7Se15

CsPbBi3Te6, CsPb2Bi3Te7, CsPb3Bi3Te8, RbPbBi3Te6, RbPb2Bi3Te7, RbPb3Bi3Te8,KPbBiSe3, K2PbBi2Se5

K2Pb3Bi2Te7, KPb4SbTe6

AgPbmSbTe2+m (LAST-m) AgPbm(Sb,Bi)Te2+m (BLAST-m)

AgSbTe

Pb

(1) (a) Rodot, H. Compt. Rend. 1959, 249, 1872-4. (2) (a) Rosi, F. D.; Hockings, E. S.; Lindenblad, N. E. Adv. Energy Convers. 1961, 1, 151.

6 8 10 12 14 16 18

263

264

265

266

267

268

Uni

t cel

l vol

ume

(Å)

Vegard's law

m value6 8 10 12 14 16 18

263

264

265

266

267

268

Uni

t cel

l vol

ume

(Å)

Vegard's law

m value6 8 10 12 14 16 18

263

264

265

266

267

268

Uni

t cel

l vol

ume

(Å)

Vegard's law

m value

(LAST-18) Ag1-xPb18SbTe20: Tunable properties Changing x

-250

-200

-150

-100

-50

0

50 100 150 200 250 300 350 400 450

Comparison of Thermopower

Ag0.73 (KF2207R2b)Ag0.76 (KF2228R3A2)Ag0.78 (KF2213R1B)Ag0.80 (KF2213R2C)Ag0.82 (KF2229R1A)Ag0.82 (KF2229R1B)Ag0.82 (KF2229R1C)Ag0.82 (KF2229R1D)

Ther

mop

ower

(µV

/K)

Temperature (K)

0

10

20

30

40

50

50 100 150 200 250 300 350 400 450

Comparison of Power Factors


Pow

er F

acto

r S2 σ

(µW

/cm

K2 )

Temperature (K)

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

80 120 160 200 240 280 320 360 400

Comparison of ZT


ZT

Temperature, K

Synthesis: Heating cooling profiles

R. G. Maier Z. Metallkunde 1963, 311

T, K

time, h

1000 ºC

Cool to 50 ºCin 24 h

Gravity induced inhomogeneity

LAST-18

time, h

T, K950-1000 ºC

Cool to 50 ºC in 72 h

13 deg/h

Ingot properties very sensitive to cooling profile

Wernick, J. H.. Metallurg. Soc. Conf. Proc. (1960), 5 69-87.

rock

rock

Samples cooled slowly from liquid to solid

Strongly varying composition from top to bottom.Strongly varying properties from top to bottom.“Sweet” spot exists with very high ZT.Mechanical properties weak. m= 40

m= 25

m= 18

m= 14m= 8

Strong composition grading along ingot

σ(S

/cm

)

S (µ

V/K

)

Properties of Ag1-xPb18SbTe20

0

500

1000

1500

2000

-400

-350

-300

-250

-200

-150

-100

300 350 400 450 500 550 600 650 700

σ (S

/cm

) S (µV

/K)

Temperature, K

0.35 W/mK (Harman PbTe/PbSe superlattice)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

Ag1-xPb18SbTe20

Hsu KF, Loo S, Guo F, Chen W, Dyck JS, Uher C, Hogan T, Polychroniadis EK, Kanatzidis MG Science, 2004, 303, 818

0.00

0.50

1.00

1.50

2.00

300 350 400 450 500 550 600 650 700

Ag0.86

Pb18

SbTe20

ZT

Temperature, K

What is the origin of the TE properties of AgPbmSbTem+2systems?

HRTEMCoherently embedded nanocrystals

Polychroniadis, Frangis, 2004 LAST-18 κlatt=1.2 W/m-K at 300 KPbTe κlatt=2.2 W/m-K at 300 K

Ag-Sb rich region

Pb- rich region

8-10 nm

Coherent compositional fluctuations in AgPbmSbTem+2

10 nm

Ag, Sb, Pb ordering

FCC lattice

Driving force for segregation Ag+/Sb3+ pair: stable

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

Any +1/+3 pair

T. Irie Jap. J. Appl. Phys. 1966, 5, 854

LAST-m

4

6

8

10

12

14

16

18

20

0 20 40 60 80 100

0 20 40 60 80 100La

ttice

The

rmal

Con

duct

ivity

(W/c

mK

)

Mol % PbTeAgSbTe2 PbTe

Klemmens-Drabble theory

Experimental Points

m=62

m=18

m=65

4

6

8

10

12

14

16

18

20

0 20 40 60 80 100

0 20 40 60 80 100La

ttice

The

rmal

Con

duct

ivity

(W/c

mK

)



Experimental Points

m=62

m=18

m=65

4

6

8

10

12

14

16

18

20

0 20 40 60 80 100

0 20 40 60 80 100La

ttice

The

rmal

Con

duct

ivity

(W/c

mK

)



Experimental Points

m~62

m=18

m=65

m=10

m~30

4

6

8

10

12

14

16

18

20

0 20 40 60 80 100

0 20 40 60 80 100La

ttice

The

rmal

Con

duct

ivity

(W/c

mK

)



Experimental Points

m=62

m=18

m=65

4

6

8

10

12

14

16

18

20

0 20 40 60 80 100

0 20 40 60 80 100La

ttice

The

rmal

Con

duct

ivity

(W/c

mK

)



Experimental Points

4

6

8

10

12

4

6

8

10

12

14

16

18

20

0 20 40 60 80 100

0 20 40 60 80 100La

ttice

The

rmal

Con

duct

ivity

(W/c

mK

)



Experimental Points

m=62

m=18

m=65

4

6

8

10

12

14

16

18

20

0 20 40 60 80 100

0 20 40 60 80 100La

ttice

The

rmal

Con

duct

ivity

(W/c

mK

)



Experimental Points

4

6

8

10

12

4

6

8

10

12

14

16

18

20

0 20 40 60 80 100

0 20 40 60 80 100La

ttice

The

rmal

Con

duct

ivity

(W/c

mK

)



Experimental Points

m=62

m=18

m=65

4

6

8

10

12

14

16

18

20

0 20 40 60 80 100

0 20 40 60 80 100La

ttice

The

rmal

Con

duct

ivity

(W/c

mK

)



Experimental Points

4

6

8

10

12

4

6

8

10

12

14

16

18

20

0 20 40 60 80 100

0 20 40 60 80 100La

ttice

The

rmal

Con

duct

ivity

(W/c

mK

)



Experimental Points

m~62

m=18

m=65

m=10

m~30Random alloy

Latt

ice

Ther

mal

Conduct

ivity

(mW

/cm

·K)

Solid solutions in (AgSbTe2)1-x(PbTe)x

below theoretical

P-type materials, LASTT(LASTT-m) Ag(Pb1-xSnx)mSbTe2+m

Sn atoms act as acceptorsAg atoms act as acceptorsSb atoms act as donorse.g AgPb10Sn8SbTe20, AgxPb7Sn3SbyTe12, Very low lattice thermal conductivityGood homogeneity

20 30 40 50 60 70 80 90 100

0

2000

4000

6000

8000

10000

12000

Inte

nsity

(arb

. uni

ts)

2Theta

Ag0.3Pb7Sn3Sb0.1Te12

0 10 20 30 40 50 600

200

400

600

800

1000

Tem

pera

ture

(o C)

t (hours)

2 hours rocking

LASTT-16Very low lattice thermal conductivity

κlatt =0.5 W/m·K at 650 K

Androulakis, Hsu, Hogan, Uher, Kanatzidis Advanced Mater. 2006, in press

LASTT-16: AgPb12Sn4Sb0.4Te20

0

40

80

120

160

200

240

280

320

320 400 480 560 640 720

See

beck

(uV/

K)

Tem perature , K


Figure of Merit LASTT (p-type)

300 400 500 600 700 8000.00.20.40.60.81.01.21.41.61.82.0

(b)

ZT

Temperature (K)

Ag0.5Pb6Sn2Sb0.2Te10 Ag0.9Pb5Sn3Sb0.7Te10 Ag0.6Pb7Sn3Sb0.2Te12

TAGS

PbTe

LASTT


NaPb20SbTe22 (SALT-20)

0

0.5

1

1.5

2

300 350 400 450 500 550 600 650 700

Latti

ce T

herm

al c

ondu

ctiv

ity (W

/mK

)

Temperature, K

PbTe0.9

Se0.1

Pb0.9

Sn0.1

Te

Na1-x

Pb20

SbTe22

(B)

(A)

50 nm

not-nano

nano

Poudeu, Hogan, Kanatzidis Angew. Chemie, 2006,

SALT-20

Poudeu, Hogan, Kanatzidis Angew. Chemie, 2006,

State of the art - bulk

0

0.5

1

1.5

2

2.5

0 200 400 600 800 1000 1200 1400

ZT

Temperature, K

LAST

LASTTNaPb

20SbTe

22

TAGS

Bi2Te

3CsBi4Te

6

Tl9BiTe

6

Ce0.9

Fe3CoSb

12

PbTe

SiGe

ConclusionsNew approaches are succeeding in raising ZTThe (A2Q)n(PbQ)m(Bi2Q3)p (Q=Se, Te) system is a rich source of new materialsSeveral new promising compounds identified

strongly anisotropiccubicnanostructured

LAST, LASTT and SALT family of materials nanostructuredsuperior ZT

Strong thermal conductivity reduction achieved through nanostructuringDoping studies and processing conditions are important in ZT optimization

OutlookFurther progress is expected on the TE figure of meritFundamental challenge:

• Translate current theoretical physical predictions on how to enhance Power Factor (σ·S2) into actual chemistry in the laboratory

• Achieve minimum thermal conductivity (~0.3 W/mK) in a bulk (nano)crystalline TE material

Research in new materials should focus on• Understanding and controlling carrier scattering• Controlling nanostructuring to manipulate phonon propagation• Discovering new compounds

Long term: Waste heat recovery and conversion could be impacted on a massive scale with low cost materials if ZT>2-3. Thermoelectrics could help utilize existing depletable energy resources more effectivelyThermoelectrics could also play role in renewable energy (e.g. solar, etc)

CollaboratorsTim Hogan, Dept of Electrical Engineering, MSUS. D. (Bhanu) Mahanti, Dept. of Physics, MSUCtirad Uher, Dept. of Physics, U of MichiganSimon Billinge, Physics, MSUEldon Case, MSUHarold Schock, MSUBruce Cook, Iowa StateTerry Tritt, Clemson UArt Schultz, Argonne NL

TE Research groupDr Duck young ChungJoseph SootsmanDr Kuei fang HsuDr Eric QuarezAurelie GuegenFerdinand PoudeuJun-Ho KimDr John Androulakis

direct energy conversion: chemistry, physics, materials science · pdf filemercouri g...

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