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Vertically Aligned Carbon Nanotubes Embedded in Ceramic Matrices for Hot Electrode Applications

mailto:[email protected]

http://lane.unl.edu/

mailto:[email protected]

http://lane.unl.edu/

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I. Goal and Objectives

II. Background and Motivations

III. Proposed Activities 1. Super growth of vertically aligned carbon nanotube (VA-CNT) carpets 2. Fabrication of CNT-boron nitride (CNT-BN) composite structures 3. Stability and resistance studies of the CNT-BN composite structures 4. Thermionic emissions of the CNT-BN composite structures

IV. Deliverables and Spending Plan

V. Student Training

VI. Preliminary Results

Outline


I - Goal and Objectives Primary goal: Develop CNT-BN composite structures in which VA-CNTs are

embedded in BN matrices for hot electrode applications in magnetohydrodynamics (MHD) power systems.

Objectives: 1. Super growth of VA-CNT carpets

2. Fabrication of CNT-BN composite structures

3. Stability and resistance studies of the CNT-BN composite structures

4. Thermionic emissions from the CNT-BN composite structures


II - Background and Motivations

How to address?

New Energy Sources High Energy Efficiency



Electricity Generation Efficiency Method Efficiency (%) Ref. Nuclear 33 – 36 Efficiency in Electricity Generation, EURELECTRIC

“Preservation of Resources” Working Group’s “Upstream” Sub-Group in collaboration with VGB, 2003 Coal 39 - 47

Natural gas < 39

http://crf.sandia.gov/index.php/coal-use-and-carbon-capture-technologies/#.VBaDbvldV8E

http://www.eia.gov/tools/faqs/faq.cfm?id=427&t=3

Coal 39%

Natural Gas 27%

Nuclear 19%

Hydroelectric 7%

Other renewable 6% Liquid petroleum 2%

U.S. Electricity Generation (2013)

http://crf.sandia.gov/index.php/coal-use-and-carbon-capture-technologies/.VBaDbvldV8E












http://www.eia.gov/tools/faqs/faq.cfm?id=427&t=3



1) Only working fluid is circulated without moving mechanical parts; 2) The ability to reach full power level almost directly. 3) Lower infrastructure cost than conventional generators. 4) A very high efficiency (60% for a closed cycle MHD). http://en.wikipedia.org/wiki/Magnetohydrodynamic_generator#Generator_efficiency


II - Background and Motivations Material Challenges for a MHD Generator

Requirement Remarks Electrical conductivity (σ) σ > 1 S/m, flux ≈ 1 amp/cm2

Thermal conductivity (k) High heat flux from the combustion fluids at 2400 K

Thermal stability Melting point (Tm) above 2400 K

Oxidation resistance Resistant to an oxygen partial pressure about 10-2 atm at

2400 K

Corrosion resistance Potassium seeds and aluminosilicate slags

Erosion resistance High velocity hot gases and particulates

Thermionic emission The anode and cathode should be good acceptor and

emitters, respectively.


III - Proposed Solution and Activities

Tasks Milestone Completion Date

1.Project Management and Planning

Complete of the proposed project within the 3-year period.

08/31/2017

2.Super Growth of Vertically Aligned CNT Carpets

Achieve the growth of VA-CNT carpets on Cu substrates with CNT lengths up to 1 cm.

08/31/2015

3.Fabrication of CNT-BN Composite Structures

Achieve uniform and dense growth of BN matrices wrapping VA-CNTs.

02/29/2016

4.Stability and Resistance studies of the CNT-BN Composite Structures

Determine the stability and resistance of the CNT-BN composite structures

08/31/2016

Determine the electrical and thermal conductivities of the CNT-BN composite structures.

02/28/2017

5.Thermionic emissions from the CNT-BN composite structures

Determine the thermionic emission performance of the CNT-BN composite structures.

08/31/2017

Project tasks, milestones, and planned completion dates


III - Proposed Solution and Activities Timelines and corresponding milestones of the project


IV - Deliverables and Spending Plan

Type Deliverables Method 1. Super-growth of ultralong VA-CNT carpets

2. Fabrication of CNT-BN composite 3. Modulated photothermal radiometric method for measuring

the thermal conductivity of the CNT-BN composite 4. Thermionic emission current method for measuring the

thermionic emission of the CNT-BN composite Equipment

setup 1. Water-vapor-assisted CVD system 2. Plasma-enhanced CVD system 3. Modulated photothermal radiometric system 4. Thermionic emission current measurement system

Reports Quarterly reports, annual reports, final report and other reports required by DOE

Presentations Conference and review meeting presentations Journal papers Journal and conference proceeding articles


V - Student Training Name Qiming Zou Degree Ph.D.

Dept. Electrical Engineering Univ. University of Nebraska - Lincoln

Goal Pursuing a Ph.D. degree in the field of Electrical Engineering and developing necessary knowledge, expertise, leadership, teaching skills, and mentorship towards an academic profession.

Objectives 1. Grasping necessary knowledge in the field of electrical engineering; 2. Grasping necessary experimental and simulation techniques required in this

project; 3. Establishing teaching skills by taking two semester teaching assistants and

participating in outreach programs; 4. Developing leadership and mentorship by working with undergraduate assistant,

Joseph Hartwig; 5. Publishing at least 3 articles in peer-reviewed journals within related fields; 6. Developing essential communication skills; 7. Attending academic conferences within related fields and establishing

networking capability; and 8. Independent and critical thinking by developing a complete research plan in his

comprehensive exam.


V - Student Training Name Joseph Hartwig Degree B.Sc.

Dept. Electrical Engineering Univ. University of Nebraska - Lincoln

Goal Completing a B.Sc. program in the field of Electrical Engineering and obtaining essential knowledge, skills, and industrial experience for pursuing a related profession.

Objectives 1. Grasping necessary knowledge in the field of electrical engineering; 2. Grasping necessary experimental and simulation techniques required in this

project; 3. Establishing essential industrial experience by conducting industrial intership; 4. Developing effective communication skills; and 5. Developing collaborative and teamwork skills.


VI - Preliminary Results

1. Growing CNTs with alignment control

2. Optically controlled in situ growth and parallel integration of CNTs

3. Direct formation of graphene on dielectric surfaces via a solid-state process

4. Laser direct writing of graphene patterns

5. Resonant vibrational excitation in diamond growth control

6. Low-temperature synthesis of GaN thin films




Ref.: Applied Physics Letters, 2009, 95(14), 143117.




Vertically aligned CNT patterns




Top view Side view

Ref.: Nanotechnology. 2010, 21, 315601




Ref.: Nanotechnology. 2010, 21, 315601




Ref.: Advanced Materials. 2013, 25, 630-634.





1200 1600 2000 2400 2800

Inten

sity (

a. u.)

Raman Shift (cm-1)

400 500 600 700 800

86

88

90

92

94

96

98

Wavelength (nm)

Tran

smitt

ance

(%)

g

h

Raman spectrum

Transmittance spectrum

2D

G

D

> 94 %

Ni/C/SiO2 pattern

e

Graphene/SiO2 pattern

f

Ni/C pattern on SiO2/Si substrate

Graphene pattern on SiO2/Si substrate

Ni/C

SiO2/Si

Graphene SiO2/Si

SiO2/Si

Origin Ni/C Graphene


Fused silica



Sapphire

Quartz

d

a

c

b

30 µm

30 µm



Ni/C/quartz Ni/quartz

Before RTP a

Sample A: Ni/quartz

Sample B: Ni/C/quartz

A B

After RTP

Nickel remained

Nickel evaporated

Graphene/quartz

b

Ni/quartz

A B

RTP (2 min)




1200 1600 2000 2400 2800

Inte

nsity

(a. u

.)

Raman Shift (cm-1)

a

Ni: 16 (nm)

32

48

65

114

130

C: 5 nm (constant)

2D G D

I2D/IG ratio

ID/IG ratio C: 5 nm

Graphene α-C & Graphene

Ni & Graphene

I II III

0 20 40 60 80 100 1200.0

0.4

0.8

1.2

1.6

Nickel thickness (nm)

Rat

io o

f pea

k in

tens

ities

b





1200 1600 2000 2400 2800

Inte

nsity

(a. u

.)

Raman Shift (cm-1)

c

C: 2.5 (nm)

4.0

5.0

6.0

7.0

8.0

Ni: 65 nm (constant) 2D

G D

2 3 4 5 6 7 8-1

0

1

2

3

4

5

Carbon thickness (nm)

Rat

io o

f pea

k in

tens

ities

Mono-layer

Bi-layer Few-layer

I2D/IG ratio

ID/IG ratio Ni: 65 nm d






Glass

LDW of graphene

Ni & C co-sputtering

Ni/C thin film

Electrode deposition

Ni/C film removing

Graphene ribbons

Ni/C thin film Glass

Glass

Graphene

X100 Lens

Glass

Fs-laser

Oil: For anti-oxidation

2 µm

2 µm

a

b

Optical Image

Raman Image

Ref.: Scientific Reports. 2014, 4, 4892




10 µm

10 µm

Text pattern

10 µm

Spiral pattern

Array of line pattern

20 µm 1 µm

800 nm

D

G 2D

1350 1800 2250 2700 Raman Shift (cm-1)

SEM micrograph

Raman NAND circuit pattern

10 nm

Bi-layer

TEM micrograph

300 400 500 600 700 80086

88

90

92

94

96

98

100

Optic

al Tr

ansm

ittan

ce (%

)

Wavelength (nm)

94.3%

Optical Spectrum

a

b

c

d

e

f h

g





Physical layout of integrated circuit (GDSII format)

Convert to “.gwl” file

Corresponding IC pattern in GWL program format

Graphene IC layouts on a glass substrate

Laser direct writing of graphene

10 µm

50 µm 10 µm 100 µm





(10.532 μm)

(10.532 μm)

(10.532 μm)




e) λ=10.551 µm

10 µm

b) λ=10.494 µm

10 µm

c) λ=10.513 µm

10 µm

f) λ=10.571 µm

10 µm

d) λ=10.532 µm

10 µm

a) No laser

10 µm




10.48 10.50 10.52 10.54 10.56 10.580

20

40

60

80

Abso

rptio

n pe

rcen

tage

(%)

Wavelength (µm)

Flame Ethylene gas

10.476 10.494 10.513 10.532 10.551 10.571 10.591

2900

3000

3100

3200

CH ro

tatio

nal t

empe

ratu

re (K

)

Laser Wavelength (µm)

No laser

Flame temperature

10.494 10.513 10.532 10.551 10.5715

10

15

20

25

30

35

40

45

Depo

stio

n Ra

te (µ

m/h

r)

Laser Wavelength (µm)

Deposition rate without laser excitations

40.8 µm

7.2 µm, No laser

10.494 10.513 10.532 10.551 10.571

99.5

99.6

99.7

99.8

99.9

Q i (%

)

Wavelength (µm)

Qi without laser excitation

99.87%

99.49%, No laser

Diamond quality Deposition rate

Flame absorption rate



6. Low-temperature synthesis of GaN thin films


Thank you!

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