Carbon dielectrics - a new chapter in the electrical ......Carbon dielectrics - a new chapter in the...

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Carbon dielectrics - a new chapter in the

electrical behavior of carbons - with

relevance to energy, conduction, sensing

and EMI shielding

Prof. D.D.L.Chung

University at Buffalo

The State University of New York

University at Buffalo,

The State University of New York

British Hong Kong

Hong Kong

World War II with the Flying Tigers in China

http://www.cnac.org/rebeccachan01.htm

First landing on the moon

July 20, 1969

Caltech 加州理工

Caltech

加州理工1973

Pol Dewez,

Father of

amorphous

metals

ResearchPushing the frontier

of knowledge

Transportation

MIT1974

Professor Mildred S. Dresselhaus, MIT

(1930-2017)

https://www.periodni.com/gallery/allotropic_forms_of_carbon.png

Graphite family(sp2 hybridization)

• Graphite

• Graphene

• Carbon fiber/nanofiber/nanotube

• Carbon black

• Activated carbon

• Turbostratic carbon

https://pubs.rsc.org/en/content/articlelanding/2017/ra/c7ra07489a#!divAbstract

Intercalation of graphite

Electrical applications of carbons in the graphite family

• Electrochemical electrodes

• Heating elements

• Electrical contacts

• Brushes (sliding electrical contacts)

• Electronic device components

Electrical applications of carbons in the graphite family

• Electrochemical electrodes

• Heating elements

• Electrical contacts

• Brushes (sliding electrical contacts)

• Electronic device components

Electrical conduction behavior

Polarization gives an electric dipole.

(separation of the positive and negative charge centers)

Dielectric behavior

- Electric polarization

- Capacitance

- Electric permittivity

Dielectric behavior

- a new chapter in the electrical behavior of

carbons in the graphite family

Carbon fiber composites

for aircraft

High modulus, high strength, low density

American Airlines Flight 587 crashed in New York in 2001

Interlaminar interface (weak link)

Lamina A

Lamina B

Contact electrical resistance of

the interlaminar interface

Effect of through-thickness compression

Carbon fiber epoxy-matrix composite

Wang, Kowalik and Chung, Smart Mater Struct (2004).

Effect of through-thickness compression

Carbon fiber nylon-matrix composite

Wang, Kowalik and Chung, Smart Mater Struct (2004).

2D spatially

resolved sensing

Smart concreteConcrete itself is a sensor.

Resistance-based

self-sensing

Invented in 1993

With carbon fiber

Tension

Thin

curve

Thick

curve

Wen and Chung, Cem Concr Res (2000).

Volume resistance

Effect of tension on the resistivity of cement with short carbon fiber

Without carbon fiber

Tension

Without fiber

Wen and Chung, Cem Concr Res (2000).

Volume resistance

Managing

the energy

usage of a

building

according to

the room

occupancy

Autonomous

vehicles

Traffic monitoring

Conventional wireless technology

http://www.leancrew.com/all-this/images2010/well.png

Oil/gas wellsGeothermal wellsCarbon sequestration wells

Oil spillhttps://phys.org/news/2010-06-storm-theatens-gulf-mexico-oil.html

Multifunctional structural materials

• The material serves structural and non-structural functions (e.g., self-sensing).

• No device involved (low cost, high durability, no mechanical property loss)

• Design simplification

• Large functional volume

0 10 20 3012400

12600

12800

13000

13200

13400

13600

30 20 10 00 20 40 6060 40 20 00 25 50 75 100100 75 50 25 0

κ

Stress (MPa)

κ

Fractional increase

0

2

4

6

8

10

Fracti

on

al

increase i

n κ

(%

)

Effect of tension in the fiber direction on the resistivity and permittivity κ

Xi and Chung, Carbon (2020).

0 10 20 30

2.7

2.8

2.9

3.0

3.1

3.2

30 20 10 00 20 40 6060 40 20 00 25 50 75 100100 75 50 25 0

Resi

stiv

ity

(1

0-4

Ω.m

)

Stress (MPa)

Resistivity

Fractional increase

0

4

8

12

16

20

Fracti

on

al

increase i

n r

esi

sti

vit

y (

%)

Resistance-based stress self-sensing

(piezoresistivity)

Capacitance-based stress self-sensing

(piezopermittivity)

Continuous carbon fiber polymer-matrix composite

Electrode

Fiber direction

Electrode

222.6

25.60 25.60

25

.60

22

2.6

25

.60

222.6

Electrode Electrode

Fiber direction

25.60 25.60

22

2.6

25

.60

25

.60

Capacitance-based damage self-sensing of carbon fiber

polymer-matrix composite using coplanar electrodes

Parallel Perpendicular

Eddib and Chung, Carbon (2018).

0.9650

0.9700

0.9750

0.9800

0.9850

0.9900

0.9950

1.0000

0 20 40 60 80 100 120

Case No.

C/C°

Parallel

Perpendicular

Relates to No. of holes in the composite

Eddib and Chung, Carbon (2018).

Electrode

Fiber direction

Electrode

222.6

25.60 25.60

25

.60

22

2.6

25

.60

222.6

Electrode Electrode

Fiber direction

25.60 25.60

22

2.6

25

.60

25

.60

Capacitance-based damage self-sensing of carbon fiber

polymer-matrix composite using coplanar electrodes

Parallel Perpendicular

Eddib and Chung, Carbon (2018).

Pitfall of capacitance measurement

• Assuming that an LCR meter applies to a conductive material in the same way as a non-conductive material

Capacitance measurement

using the parallel-plate capacitor configuration

C = εo κA/l

Add a dielectric (insulating) film between the specimen and the electrode

for measuring the permittivity, but not for measuring the resistivity.

Solution

Electrical insulator

Specimen

Electrode

Electrical insulator

Specimen

Electrode

Volume and contact capacitance in series: 1/C = 1/Cv + 2/Ci

Thus, volumetric and interfacial contributions are decoupled.

Slope gives relative dielectric constant

1/C = l /(εo κ A) + 2/Ci

Intercept gives interfacial capacitance

Three thicknesses

Capacitance-based self-sensing of

carbon fiber composites implies that the

composites are conductive dielectrics.

C

-

+ I

(Pulse)

I

(Continuous)R

+

-

DC current pulse only.AC current if there is a time-varying stimulus

Continuous DC current.Time-varying stimulus not required.

C refers to the capacitor. R refers to the resistor. I refers to the current.

Nonconductive dielectric(capacitor)

Conductive dielectric(resistor)

I

(Continuous)R

+

-

Continuous DC current.Time-varying stimulus not required.

R refers to the resistance. I refers to the current.

Conductive dielectric (conductor that is polarizable)

This requires electron-atom interaction, which is enhanced by defects, such as grain boundaries.

+ -

+-

Time

Ap

pa

ren

t re

sis

tan

ce

True resistance

R1

Polarity

reversal

R2

Time

Ap

pa

ren

t re

sis

tan

ce

True resistance

R1

Polarity

reversal

R2

The average of R1 and R2 equals the true resistance.

Polarization under a DC current

Depolarization upon polarity reversal

Polarization impedes DC conduction

increasing the apparent resistivity.

0 100 200 300 400 500 600 700 800 900-1.5

-1.0

-0.5

0.0

0.5

1.0

1.5

2.0

2.5

1mA

5mA 10mA20mA

Fra

ctio

na

l ch

an

ge

in a

pp

are

nt

resi

stiv

ity

(%

)

Time (s)

40mA

-1.5

-1.0

-0.5

0.0

0.5

1.0

1.5

2.0

2.5

Fra

ctio

na

l ch

an

ge

in e

lect

ric

fiel

d (

%)

Graphite

Chung and Xi, Carbon (2021).

Depolarization is slower and less than polarization, due to electrical asymmetry.

Polarization

Depolarization

https://www.science.org.au/curious/technology-future/batteries

The electrodes of a battery can undergo polarization, increasing their apparent resistivity.

https://medium.com/@danielrom/whats-going-on-with-the-graphite-electrodes-8ea80936c81a

https://refractoriesmaterials.com/graphite-electrodes-for-sale/

Large graphite

electrochemical electrodes

for aluminum production

Graphite heating elements

https://www.graphitemachininginc.com/vacuum-furnace-industry.htmlhttps://www.graphite-eng.com/applications/

https://www.alibaba.com/product-detail/China-custom-carbon-graphite-strip-for_60757048471.html

https://kitairu.net/minerals-and-metallurgy/metals-and-metal-products/nonferrous_and_rare_metals/non_metallic_minerals/non_metallic_mineral_products/graphite_products/541713.html

Graphite brushes

(sliding electrical contacts)

Pantographs

0 2 4 6 8 10 120

500

1000

1500

2000

2500

3000

3500

4000

4500

5000

5500

AR-08 (Mersen)♠

★♥

AR-14 (Mersen)♣

♣●

Rela

tiv

e p

erm

itti

vit

y

Grain size (μm)

■ ZXF-5Q (Entegris)▲ TTK-4 (Toyo Tanso)

● AXF-5Q (Entegris)

★ AR-06 (Mersen)

♥ AR-12 (Mersen)

0.0 0.2 0.4 0.6 0.8 1.00

500

1000

1500

2000

2500

3000

3500

4000

4500

5000

5500

♠★♥

♣●

Rel

ativ

e p

erm

itti

vity

1/grain size (μm)

■ ZXF-5Q (Entegris)▲ TTK-4 (Toyo Tanso)

● AXF-5Q (Entegris)

♣ AR-14 (Mersen)

♥ AR-12 (Mersen)

★ AR-06 (Mersen)

♠ AR-08 (Mersen)

Polycrystalline graphite

Effect of the grain size on the

permittivity

Electron-atom interaction occurs at

the grain boundaries, with the

strength of the interaction

independent of the grain size.

Xi and Chung (2021)https://www.carbon.co.jp/english/products/specialty/

GraphiteA decrease in the grain size

greatly increases the

permittivity, but increases the

resistivity slightly. (Xi and

Chung, 2021)

Carbon fiber (along the fiber axis)

An Increase in the degree of

graphitization decreases the

resistivity greatly, but increases

the permittivity much less.

(Eddib and Chung, 2019)

20 30 40 50 60 70500

550

600

650

700

70 60 50 40 30 20

Relative permittivity

Rela

tive p

erm

itti

vit

y

Heating

Fractional increase

Temperature (C)

Cooling

0

5

10

15

20

25

30

35

40

Fracti

on

al

increase

in

rela

tiv

e p

erm

itti

vit

y (

%)

Graphite (25-μm grain size)

Permittivity and resistivity increase with temperature for graphite.

- No Curie effect

Permittivity decreases with temperature for nonconductive dielectrics.

- Curie effect

Pyropermittivity(not pyroelectricity)

Heating increases the permittivity reversibly.

0.0 0.1 0.2 0.3530

540

550

560

570

580

590

600

0.3 0.2 0.1 0.00.0 0.1 0.2 0.3 0.3 0.2 0.1 0.00.0 1.0 2.0 2.0 1.0 0.00.0 1.0 2.0 2.0 1.0 0.00.0 2.0 4.0 6.0 6.0 4.0 2.0 0.00.0 2.0 4.0 6.0 6.0 4.0 2.0 0.0

Rela

tiv

e p

erm

itti

vit

y

Stress (MPa)

Relative permittivity

Fractional increase

0

2

4

6

8

10

12

14

Fra

cti

on

al

increa

se (

%)

Piezopermittivity

(not piezoelectricity)

Graphite (25-μm grain size)

Tensile stress increases the permittivity reversibly.

Electret

Permanent electric dipole

Electret – material with a permanent electric dipole

Electric field

associated with

an electret

The H2O molecule is a permanent electric dipole,

which is thermodynamically stable.

https://socratic.org/questions/5674189d11ef6b3382d73f32

Conventional electret True electret

Requires poling. Does not require poling.

Polarized state is

thermodynamically unstable.

(Low entropy)

Polarized state is

thermodynamically stable.

(Low enthalpy)

Depoles spontaneously after

poling.

Does not depole

spontaneously.

Depolarized state is

thermodynamically stable.

(High entropy)

Depolarized state is

thermodynamically unstable.

(High enthalpy)

True electret can serve as an energy source

that does not need energy input during

charge – self-charge. (Patent pending)

0.0 0.1 0.2 0.3

1.2

1.3

1.4

1.5

1.6

1.7

1.8

0.3 0.2 0.1 0.00.0 0.1 0.2 0.3 0.3 0.2 0.1 0.00.0 1.0 2.0 2.0 1.0 0.00.0 1.0 2.0 2.0 1.0 0.00.0 2.0 4.0 6.0 6.0 4.0 2.0 0.00.0 2.0 4.0 6.0 6.0 4.0 2.0 0.0

Ele

ctr

ic f

ield

(1

0-5

V/m

)

Stress (MPa)

Electric field

Fractional increase

0

10

20

30

40

50

60

70

Fracti

on

al

increase i

n e

lectr

ic f

ield

(%

)

Piezoelectret

(not piezoelectricity)

Graphite (25-μm grain size)

Tensile stress increases the electric field.

Charge-discharge testing results for 37.0% cold-worked copper

Charge-discharge behavior (graphite, 1 μm grain size)

Xi and Chung. Carbon (2021); Smart Mater Struct (2019).

0 100 200 300 4000.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

2.0

0 100 200 300 400

ChargeDischarge

|E2| (1

0-4

V/m

)

Time (s)

0

1

2

3

4

5

6

7

8

9

J2 (

A/m

2)

Short-circuited Open-circuited

-+

pn

Electric field enables discharge

current, so no bias is necessary.

Electret

- +

Electrons

Electrons

pn-junction

Electric field is against the forward

current, so forward bias is necessary.

-+

pn

Electric field enables discharge

current, so no bias is necessary.

Electret

- +

Electrons

Electrons

pn-junction

Electric field is against the forward

current, so forward bias is necessary.

Natural

true

electret

Artificial

true

electret

Bias is not suitable for providing energy.

Energy issues

• The greenhouse gas emission associated with the burning of fossil fuels

• The environmental pollution associated with the disposal of batteries and supercapacitors

• The fire hazard of some batteries and supercapacitors

• The inadequate safety of nuclear reactors

• The high cost of photovoltaics (solar cells)

Batteries

causing fire

https://www.westborotoyota.com/toyotas-scientists-create-intelligent-battery-with-magnesium/

Battery discharge (spontaneous)

Battery recharging limiting the travel

distance and vehicle utilization

Batteries take up volume and weight,

limiting payload and increasing fuel need.

Supercapacitor

https://energyeducation.ca/encyclopedia/Supercapacitor

Discharge is spontaneous.

https://www.smithsonianmag.com/innovation/lets-build-cars-out-batteries-180970693/

Battery incorporation weakens a structure.

Battery life is much shorter than the required service life of the structure.

Structural battery or capacitor (Chung, 1st report, 2001)

Issues with structures rendered self-powering by

device embedment

• Inadequate service life and inadequate safety for structural batteries and structural supercapacitors

• Inadequate self-powering performance

• Inadequate mechanical performance

• High cost

• Technology not applicable to existing structures

Vertical take off and landing

(all electric, high agility)

Air taxi, air metro, last-mile delivery

Electret

Permanent electric dipole

Electret – material with a permanent electric dipole

Electric field

associated with

an electret

The electric field changes sign upon polarity reversal and increases

linearly in magnitude with increasing inter-electrode distance l.

This means that the voltage relates to l2.

Graphite (25 μm grain size)

Xi and Chung, Carbon (2021).

E1

E2

Before polarity reversal

After polarity reversal

0 200 400 600 800 1000 1200 14000

20

40

60

80

100

120

140

Ele

ctri

c fi

eld

(10

-6 V

/m)

l (m)

Copper

Xi and Chung, Smart Mater Struct, 2019.

The linearity is valid even at very large distances.

Up to 1280 m

The charge magnitude Q at each

end of the dipole increases linearly

with decreasing grain size.

The electric field is governed more

by the resistivity than the

permittivity.

Graphite

0 2 4 6 8 10 122.6

2.8

3.0

3.2

3.4

3.6

3.8

4.0

4.2

4.4

4.6

|E2| (

10

-5 V

/m)

Grain size (μm)

Resistivity increases

linearly with

decreasing grain size.

0 2 4 6 8 10 120

500

1000

1500

2000

2500

3000

3500

4000

4500

5000

5500

AR-08 (Mersen)♠

★♥

AR-14 (Mersen)♣

♣●

Rela

tiv

e p

erm

itti

vit

y

Grain size (μm)

■ ZXF-5Q (Entegris)▲ TTK-4 (Toyo Tanso)

● AXF-5Q (Entegris)

★ AR-06 (Mersen)

♥ AR-12 (Mersen)

The electret’s electric

field (l fixed at ~16 mm)

increases linearly with

decreasing grain size.

0 5 10 15 20 25 30 35 400

1

2

3

4

5

Inh

eren

t E

lect

ric

fiel

d (

10

-5 V

/m)

Prior cold work (%)

The electret is enhanced by cold work (rolling), as shown for copper.

The positive end of the

electret’s voltage located

where the rolling-induced

plastic flow originates.

The electret is enhanced by cold

work (rolling), as shown for copper.

The scientific origin of true electrets relates to the inherent electrical asymmetry

in the material. This asymmetry stems from the directional nature of the material

fabrication (e.g., extrusion, drawing, rolling, pressing, etc.).

Xi and Chung, submitted.

Charge-discharge testing results for 37.0% cold-worked copper

Charge-discharge behavior (graphite, 1 μm grain size)

I

Discharge

Charge

t

Shaded area =

charge involved

Xi and Chung, Carbon (2021); Smart Mater Struct (2019).

0 100 200 300 4000.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

2.0

0 100 200 300 400

ChargeDischarge

|E2| (1

0-4

V/m

)

Time (s)

0

1

2

3

4

5

6

7

8

9

J2 (

A/m

2)

Short-circuited Open-circuited

Grain

size

(μm)

Relative

permittivity

(2 kHz)

Energy

density

(J/m3)

Fraction of

carriers that

participate

Discharge time

per unit

participating

charge (s/C)

25 5.3×102 5.2×10-1 4.9×10-4 3.6×105

1 5.1×103 8.2×105 9.3×10-2 1.3×103

True-electret-based energy density (scaled to inter-electrode

distance l = 1400 mm) and related properties of graphite

The grain size reduction increases the energy density and the fraction of carriers

that participate, and shortens the discharge time per unit participating charge.

The fraction of carriers that participate in the permittivity is lower than the fraction

of carriers that participate in electret discharge by 9 orders of magnitude.

Relative

permit-

tivity

(2 kHz)

Energy

density

(J/m3)

Fraction of

carriers

that

participate

Discharge time

per unit

participating

charge (s/C)

Uncoated 1.2×104 7.2 1.3×10-3 4.8×106

Nickel-

coated

6.3×104 3.1×102 3.4×10-5 3.1×104

True-electret-based energy density (scaled to inter-electrode

distance l = 1400 mm) and related properties of carbon fibers

Carbon fiber

The nickel coating increases the energy density, decreases the fraction of carriers

that participate, and shortens the discharge time per unit participating charge.

Grain

size

(μm)

Relative

permittivity

(2 kHz)

Energy

density

(J/m3)

Fraction of

carriers that

participate

Discharge time

per unit

participating

charge (s/C)

25 5.3×102 5.2×10-1 4.9×10-4 3.6×105

1 5.1×103 8.2×105 9.3×10-2 1.3×103

True-electret-based energy density (scaled to inter-electrode

distance l = 1400 mm) and related properties of graphite

The grain size reduction increases the energy density and the fraction of carriers

that participate, and shortens the discharge time per unit participating charge.

The fraction of carriers that participate in the permittivity is lower than the fraction

of carriers that participate in electret discharge by 9 orders of magnitude.

Fraction of carriers that participate in true electret (graphite)

• 9 orders higher than that for permittivity (capacitance)

• 14 orders higher than that for current-induced

polarization (increase in the apparent resistivity)

Need to tailor carbons for electret-based energy generation

Processing-structure-property relationships

20 40 600.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

2.0

60 40 20 20 40 60 60 40 20

Heating

E1

E1 (

10

-3 V

/m)

Temperature (℃)

Fractional increase

HeatingCooling Cooling

0

2

4

6

8

10

12

14

Fra

ctio

n i

ncr

ease

in

E1

Electric field increases by 1100% upon heating to 70°CGraphite (1 μm grain size)

20 40 600.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

2.0

2.2

60 40 20 20 40 60 60 40 20

CoolingCoolingHeating

Resistivity

Res

isti

vit

y (

10

-5 Ω

.m)

Temperature (℃)

Fractional decrease

Heating0

10

20

30

40

50

60

70

80

Fra

ctio

na

l d

ecre

ase

in

res

isti

vit

y (

%)

Pyroelectret

20 40 600

20

40

60

80

100

120

140

160

60 40 20 20 40 60 60 40 20

CoolingHeating

Current density

Cu

rren

t d

en

sity

(A

/m2)

Temperature (℃)

Fractional increase

Heating Cooling0

10

20

30

40

50

60

Fracti

on

al

increase

in

cu

rren

t d

en

sity

Current density increases by 5000% upon heating to 70°C

Graphite (1 μm grain size)

0 50 100 1500.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

2.0

0 200 400 600

E1 (

10

-3 V

/m)

Time (min)

Electric field

Temperature

Short-circuit condition

Time (min)

20

30

40

50

60

70

80

Tem

per

atu

re (

℃)

Graphite at 70°C

Open circuit

The electret is so strong that the electrical disturbance upon short-

circuiting is small, so that the thermodynamic driving force for discharge

is small and the discharge is slow, with a long incubation time; similarly,

charge is slow.

~18 hours before the discharge starts

~25 hours when the discharge finishes

Incubation time ~18 h

Discharge / charge time ~ 7 h

Charge-discharge testing results for 37.0% cold-worked copperGraphite at 20°C

0 100 200 300 4000.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

2.0

0 100 200 300 400

ChargeDischarge

|E2| (1

0-4

V/m

)

Time (s)

0

1

2

3

4

5

6

7

8

9

J2 (

A/m

2)

No incubation period

Discharge / charge time = 400 s

Electrons

- +

Forward bias (promotes discharge)

Electrons

Reverse bias (promotes charge)

+-

Electret

Bias is not suitable for providing energy.

0 400 8000.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

0 400 800 0 400 800 0 400 800 0 400 800 0 400 800

Time (s)

|E2| (1

0-5

V/m

)

Discharge Discharge DischargeChargeCharge Charge

0.0

0.2

0.4

0.6

0.8

1.0

1.2

|J2| (1

02 A

/m2)

30 60 90 120 150 180 2102.22

2.24

2.26

2.28

2.30

2.32

Ele

ctri

c fi

eld

(1

0-5

V/m

)

l (mm)

Low carbon steell = 18.1 mm

Energy density for a single

discharge, with l = 1400 mm,

Steel: 9.1×104 J/m3

Graphite (1 μm grain size): 8.2×105 J/m3

37% cold worked copper:2.2×105 J/m3

Steel-reinforced concrete

With 10 discharges per day, a structure comprising 100 steel rebars of

length 60 ft and diameter 1.27 inch provides 3.2 GJ, i.e., all of the daily

energy need of 2.8 average U.S. households.

Zero-energy buildings

Residential and commercial buildings account for

nearly 40% of the nation’s total energy demand.

The life-cycle cost of using steel is estimated to be

1% of that of solar energy.

Many buildings in a city for providing steel

for energy generation

Electric car

Vertical take off and landing

(all electric, high agility)

Structural energy

• Energy generated by structures that are

conductive dielectrics and true electrets

(patent pending)

• Structural materials include metals and carbons.

• A new untapped form of energy

• No energy storage needed.

• No greenhouse gas emission

Carbon fiber composite

for computer case

capable of

electromagnetic

interference (EMI)

shielding

https://static-defendershield.netdna-ssl.com/wp-content/uploads/sources-emf.jpg

Electromagnetic radiation sources

Stealth

“Flexible graphite”

is compressed

exfoliated graphite.

Structure formed by mechanical interlocking of

exfoliated graphite particles (no binder)

130 dB at 1 GHz

Luo and Chung, Carbon (1996).

Intercalated, but before exfoliation

After exfoliation

Exfoliated graphite

“Flexible graphite”

is compressed

exfoliated graphite.

Structure formed by mechanical interlocking of

exfoliated graphite particles (no binder)

130 dB at 1 GHz

Luo and Chung, Carbon (1996).

Absorption contribution = SEA/SET

SEA>> SER

Flexible graphite of thickness 0.13 mm

• Dielectric

• High specific surface area

• Conductive

• Resilience

Guan and Chung, Carbon (2020).

Radio wave and microwave regimes

Scientific pouring

https://www.fearlessmotivation.com/2019/03/28/breakthrough-motivational-video/

Not just an incremental advance, but is transformative.

https://www.resourcesforleading.com/blog/2015/07/success-at-last-stepping-out-of-the-box/

Think out of the box

https://medium.com/@rtaori60/leader-or-follower-2885adc7f92b

Be a leader, not just a follower

Sustained

work

https://innovationmanagement.se/2005/06/09/7-strategies-for-sustained-innovation/

Chung

Google Scholar

H-index = 98

Citations: 34603

Professor Mildred S. Dresselhaus, MIT (1930-2017)

Dresselhaus

Google Scholar

H-index = 187

Citations: 211,122

https://info.wartburg.edu/Pathways/Discover-Your-Vocation/Definition-of-Vocation

IQ -- Intelligence Quotient

EQ – Emotional Quotient

SQ – Spiritual Quotient

4 generations of carbon scientists at Carbon 2016 Conference

2018 book dedicated to the memory of Prof. M.S. Dresselhaus

In memory of Professor M.S. Dresselhaus

July 2016

D.D.L. Chung, "Mildred S. Dresselhaus (1930-2017)", Nature 543, 316 (2017).