PREM Program: Coalition
of Research and Education in Materials (DMR 0934142)
Annual Progress Report
(09/01/2009-06/01/2010)
The online version has removed
sensitive information about names of the faculty and students.
1. Executive
Summary (maximum 2 pages)
1.1 Vision
statement
The vision of the PREM is to
integrate research, education, and student-mentoring in order to increase the
number of underrepresented students pursuing graduate degrees and to increase
their overall participation in the field of materials science and engineering.
1.2 Key
Accomplishments in terms of Intellectual
Merit and Broader Impacts
Intellectual Merit:
The PREM has both enhanced existing interactions/collaborations between Clark
Atlanta University (CAU) and Georgia Tech (GT), and spawned new
collaborations. Specifically, the
collaborations have been furthered by first-principles
density-functional-theory based calculations to investigate structural and
electronic characteristics of functionalized graphene nanoribbons, hydrogenated
graphene and nanoribbons, bilayer graphene under electric bias, graphene oxide.
The research results have been published in high-impact journals such as ACS Nano (impact factor 7.5), Nanoscale, and J. Phys. Chem. Lett. A new collaboration has begun wherein surface
analyses are being used to investigate and understand the electronic structure
and properties of epitaxial graphene (EG).
GT brings chemical bonding and EG preparation experience to this effort,
while CAU offers ultra-high vacuum surface analysis expertise and
equipment. Close interactions have been
promoted by the joint supervision of a high school physics teacher during
summer 2010 In addition, a new faculty hire in the Chemistry Department at
Morehouse, will be having discussions regarding possible collaborations with
the GT MRSEC. Researchers at Spelman have carried out simulation studies for the
interaction between graphene and molecules such as water and methanol. In
collaboration with GT MRSEC, AUC faculty acquired graphene samples and
additional samples will be prepared at GT.
We have updated the
experimental facility and acquired a state-of-the-art GPU system for high
performance computing. This will allow us investigate the graphene system in
the coming years.
Broader Impacts:
Nine underrepresented minority students took part in the PREM projects
involving both experimental and theoretical study of nanosystems.
The students and postdoctoral fellow have acquired experience in
high-performance computer simulations and software development, including the
areas of parallel computer architecture, high-performance FORTRAN as well as
GPU coding, and materials theory. In particular, they are developing skills in
using computers for performing atomistic simulations and state-of-the-art
experimental characterization of graphene and related nanostructure systems. The
2010 summer program has been planed and scheduled.
1.3 Describe
the PREM’s response to any site visit recommendations.
Program officers of PREM visited
Clark Atlanta University on March 1, 2010.
During the visit, Dr. Ishrat Khan
made a presentation on behalf of Dr. Macus Shute (VP for Research and Sponsored
programs, Clark Atlanta University) concerning the Materials Science Programs
at Clark Atlanta University.
2. Lists of Current
PREM Participants including their names and academic department in the
following categories:
Indicate at
the end of each participant list the total number of women, and
underrepresented minorities in science in the following categories: Hispanic,
African American, Native American, and Pacific Islanders. Except
for undergraduates, please report two sets of numbers following each
participant list: (1) All URM* (irrespective of Visa / Citizenship status), and
(2) US URM (Those who are US citizens or Permanent Resident Aliens).
Summary: Total 24 participants. 17 ALL URM; 16 US URM; 7 Women
3. Research
Accomplishments and Plans
The objective of the PREM project
is to establish an integrated research, education, and student-mentoring
program in order to increase the number of underrepresented students pursuing
graduate degrees and to increase their overall participation in the field of
materials science and engineering. The joint research effort focuses on experimental
characterization of epitaxially grown graphene and simulation studies of the
electronic structures of graphene-related nanodevices. The key features of the
proposed PREM research component include: (1) establishing research
collaborations between AUC and GT faculty, postdoctoral associates, and
graduate students; (2) strengthening the research and education infrastructure
of AUC; and (3) providing research opportunities for AUC undergraduates during
the academic year.
The names of the faculty and students
involved in each project are marked with bold and underlines,
respectively. The support from GT MESEC has been vital for the research projects.
In the following we highlight the research performed and the most significant results obtained.
(i)
Ultraviolet Photoemission Study of Graphene
Crystalline Quality
If epitaxial graphene (EG) is to
realize its potential as the successor to silicon for next generation microelectronic
devices and integrated circuits (ICs),
methods to grow high quality EG layers with controllable and
reproducible chemical and physical structure and properties are required. Currently, the highest quality layers are
grown by silicon evaporation from SiC substrates as pioneered by Walt de Heer
and co-workers at GT. However, the
dependence of physical and electronic properties such as surface crystallinity,
layer morphology and EG valence band structure has not been correlated with
growth conditions. Understanding these
relationships will forge a path for improvement of the quality and thus
suitability of EG for future ICs. In
addition, this work may identify an analysis method that can establish the
relative quality of the layers prior to device fabrication and testing.
EG samples were grown on SiC
substrates at GT under different reactor conditions that resulted in different
thickness and different surface morphologies/crystallinity. From previous studies in the de Heer group,
EG quality as determined by electron mobility of these two samples depended
upon the specific growth conditions. These samples were analyzed by ultraviolet
photoelectron spectroscopy (UPS) to determine the valence band structure of the
two samples. The valence band width and
lineshapes varied with growth conditions, thereby indicating that UPS is a good
measure of crystallinity and therefore EG quality. Comparison of these results to UPS spectra of
graphite will allow a more detailed description of the differences between the
morphology of EG layers grown under different conditions and the more
traditional structure of graphite. Such
investigations will offer fundamental insight into the relationship between
growth conditions and improved quality EG.
The electronic transport and
optical properties of modern electronic devices are governed by the electronic
structure at the surface and interfaces of the material constituents. UPS probes the first 4-5 Å of the material and shows a significant difference in the
electronic structure of a thin optically smooth 2.4 nm thick sample versus that
of a thicker (6.0 nm) topologically rough sample. The electronic structure is also modified
with an applied electric field and suggests the possibility of cold electron
emission for application to display technology.
The experimental study reveals that the electronic structure of the material is
strongly influenced by the degree of surface crystallinity or film
morphology.
(ii)
Structural and Electronic Characteristics of
Graphene Nanoribbons, Hydrogenated Graphene, and Bilayer Hydrogenated Graphene
under Electric Bias
Energy Gaps in Supramolecular Functionalized Graphene Nanoribbons:
The electronic structure characteristics of supramolecular functionalization of
graphene nanoribbons with π-conjugated polymers are investigated using
first-principles density functional theory. Noncovalent polymer
functionalization leads to distinct changes in the electronic properties,
particularly the band gaps of metallic and semimetallic graphene nanoribbons. A
detailed analysis of band alignments reveals a profound level hybridization for
ribbons with various shaped edges and spin density waves near the edges of
zigzag ribbons. The extracted planar polymer conformations and the
disappearance of the metallic behavior are in conformity with experimental
observations.
We have performed comprehensive
studies for the electronic structure of conjugated polymer PmPV-functionalized
graphene nanoribbons (GNRs). The important role of the edge bond relaxation and
the noncovalent functionalization on electronic structure characteristics is
investigated. For zigzag-GNR (ZGNR), the ground state changes from 2D staggered
antiferromagnetic
state for pristine ribbons to the edge-confined spin density wave state for the
PmPV-functionalized ZGNRs. Our results demonstrate that noncovalent polymer
functionalization could be used to tailor the band gap of a fixed GNR width,
resulting in the enhancement of device performances. It is straightforward to
employ this approach to novel noncovalent functionalizations with a variety of
π-conjugated polymers, and the investigation of the relevant electronic
structures will provide an invaluable tool for developing graphene-based
nanodevices. The work was published in ACS
Nano.
Chair and Twist-Boat Membranes in Hydrogenated Graphene:
Graphane is a two-dimensional system consisting of a single planar layer of
fully saturated carbon atoms, which has recently been realized experimentally
through hydrogenation of graphene membranes. We have studied the stability of
chair, boat, and twist-boat graphane structures using first-principles density
functional calculations. Our results indicate that locally stable twist-boat
membranes significantly contribute to the experimentally observed lattice
contraction. The band gaps of graphane nanoribbons decrease monotonically with
the increase of the ribbon width and are insensitive to the edge structure.
On
the basis of first-principles density-functional calculations, we have studied
various stable crystal structures of graphane and demonstrated that locally
stable twist-boat membranes significantly contribute to the experimentally
observed lattice contraction. The first-principles results shed considerable
light on the electronic characteristics associated with the sp3
hybridization. Moreover, the first-principles approach can be employed to
structural and electronic properties of hydrogenated graphene derivatives. The
work was published in ACS Nano, and
was cited by
ACS as major research news on the ACS portal front page December 1-14, 2009.
Nano-reinforcement of nanocomposites: Nanocomposites are of increasing interest due to their
unique structural, electronic, and thermal properties. Simultaneously, multi-scale molecular
modeling is becoming more robust in accordance with Moore’s Law as computing
memory, power, and speed continue to improve.
Computational models are able to be examined with increased accuracy,
complexity, and dimension. Graphene
based molecules are lauded for their conductive properties as well as their
architecture-like geometry which may allow bottom up nanoscale fabrication of
nanoscopic structures. Furthermore,
these macro-cycled molecules allow high interactivity with other molecules
including highly tensiled polymers that yield other novel supramolecular
structures when interacted. These
supramolecular structures are being investigated in lieu of a variety of potential
military and commercial applications.
A fundamental issue is how the self-organized dynamic structure of
functional molecular systems affects the interactions of the nano-reinforced
composites. To this end we employ a combination of force-field based molecular
dynamics and local density-functional calculations. Force-field-based molecular
dynamics was used to pre-select molecular geometries, and first-principles
calculations were employed to determine the electronic structure of the
nano-reinforced composites. Our results show that the stacking between the
aromatic macrocycle and the surface of the SWNTs manifests itself via increased
interfacial binding. First-principles calculations on the electronic structures
further reveal that there exists distinct level hybridization behavior for
metallic and semiconducting nanotubes. In addition there is a monatomic
increase in binding energy with an increase in the nanotube diameter. Our simulation studies suggest that graphene
nanoplatelets are potentially the best fillers of epoxy matrices. The figure
shown on the left presents molecular dynamics simulation of EPON 862 and curing
agent W chain interacts noncovalently with a graphene nanoplatelet. The primary
results were published in Nanoscale
as a Communication.
(iii) Experimental and Theoretical Study of
Interactions between Graphene and Molecules
Recent research studies have
shown that metal incorporated graphene systems are potentially promising semiconductor
systems at nanoscale region. As a first step towards understanding the
interaction of graphene with other molecules especially metals, we started
looking at interaction of water and methanol with graphene from a theoretical
standpoint. Water and Methanol are common stable substances that are capable of
impacting the properties of graphene and are used as materials on graphene as
they are capable of forming stable hydrogen bonding with graphene and are
believed to have the potential to alter electron conductivity of graphene
material. In order to see the pattern of
interaction, calculations are performed with graphene consisting of four or
seven benzene rings with water and methanol using the density 
functional
approach. The quantum chemical calculations use the wave function of a given
system in a defined basis to perform calculations. The calculations have been
performed using density functional theory and
the 6-31G*+ basis sets
to find a stable state for each of the interacting systems. From the
computational results, optimal orientation and distance of the molecules with
respect to the graphene plane are determined and the total energy of the final
is also calculated. A
undergraduate physics major worked on this project since October 2009 and will continue
this summer supported by PREM.
A sample containing metal iron on
graphene is currently being prepared by GT collaborators and Mössbauer
spectroscopic studies will be undertaken as soon as the sample becomes
available. In the meantime, a student was
entrusted to read and understand the theory and the instrumentation of
Mössbauer spectroscopy by performing a case study of phase transition in a
ferrite material CaFe2O4.
This material was prepared using conventional high-temperature ceramic
technique using CaO and Fe2O3 at 12000C
sintered three times until X-ray pattern established the purity of the
sample. Temperature dependence of
Mossbauer data were measured from 100 to 300 K and Weiss molecular field theory
was employed to model the experimental behavior of the system. 57Fe
Mössbauer spectroscopy is thoroughly exploited to understand the symmetry
around Fe-nucleus, its oxidation state, and the internal magnetic field. A
phase transition temperature of around 208 ± 8 K is deduced from the
temperature dependence of the Mössbauer
experimental data and is described to be an order-disorder (magnetic–non
magnetic) type. A theoretical approach based on the molecular field approximation is
used to model the experimental results.
Both students presented their
scientific finding at Spelman Research Day (April 2010) and also at National
Council of Undergraduate Research (NCUR April 2010) at the University of
Montana, Missoula.
(iv) Engineering
Environmentally-Responsive Graphene Sheets
The research focuses on designing
smart thermo-responsive materials to present an innovative surface property to
graphene sheets. Poly N-vinylcaprolactam
(PVCL) is a polymer that has the ability to undergo phase transitions due to the
unique capability of changing its molecular conformation in response to
temperature. The molecular change that PVCL exhibits is attributed to lower
critical solution temperature (LCST) where phase separation is induced by
surpassing a certain temperature threshold. Towards this end, our interests are
geared towards investigating how temperature change may affect the properties
of graphene. The methods consist of using photometry to confirm LCST and
non-contact AFM to identify morphology changes of PVCL on graphene.
Research plans for the coming year: Encouraged by the progress during the first nine months of the PREM
project, we plan to continue the experimental and theoretical studies of
graphene and related nanostructed systems.
4. Education (limit
5 pages)
Objective of PREM Education:
The objective of the PREM education component involves (1) providing summer
research experiences for AUC juniors and seniors at GT through the
collaborative research program; (2) exposing incoming AUC freshman to materials
science through the Pre-Freshman Bridge
Summer Program (3) organizing workshops, seminars, and annual symposia
at AUC and GT and disseminating results at professional meetings and
conferences; and (4) developing and hosting a summer research institute for
high school teachers which has been named PREM Teacher Training Program.
Description of the Roles of the
Partner Institution: Morehouse
College is hosting the Pre-freshmen Bridge Summer Program which serves as the
venue for the PREM Teacher Training Program.
Each of the partner institutions plays a role in the planning and
implementation of this program via the Education Internal Advisory
Committee. High school teachers that are
selected to participate in the Morehouse College sponsored PREM Teacher
Training Program will have the opportunity to participate in the Georgia Tech
MRSEC research laboratories the following summer.
Description of the Significant Results
Obtained: Significant work has been accomplished in
order to conduct the first PREM Teacher Training Program in 2010. A consultant Pauline Washington was hired as
a liaison to the Atlanta Public Schools.
For the Atlanta Public Schools to allow outside organizations to
advertise and recruit teachers, a proposal had to be written and submitted to
the Atlanta Public School System. This
proposal was submitted in February and approved in March 2010. This approval was given for specific schools
in the Atlanta
system for duration of five years. For
2010, four schools were targeted (Washington High School, Carver School of
Technology, Carver School of Health and Research and Therrell High School), and
the Principles of these schools were contacted and asked to recommend their top
science teachers for the PREM Teacher Training Program. Seven teachers were identified, a
professionally developed brochure on the program was sent to these teachers,
and they were contacted in person. Upon
receiving applications from the teachers, the Education Internal Advisory
Committee members (see table above) selected four teachers to participate in
the 2010 summer program.
High school teachers in the PREM
Teacher Training Program will develop laboratory skills, learn new pedagogical
skills and concepts in materials science and the scientific process by working
along with faculty members that teach in a Pre-Freshman Bridge Summer Science
Program designed for 20 students. The
following description of this pre-freshman summer program gives a description
of the curriculum that the high school teachers will be involved with.
The
Pre-Freshman Bridge Summer Program is designed to expose students to materials
science and develop an advanced level of scientific literacy among pre-freshmen
science and mathematics majors with a goal of increasing the number of
graduates who enter graduate school in pursuit of research careers. In this
innovative six-week summer experience students participate in quantitative
literacy, guided inquiry laboratories, research seminars, scientific
field trips, as well as personal and professional development.
Quantitative literacy classes conducted daily give
students practice in applying mathematics to a broad range of problems and
assists them in overcoming mathematical barriers in gatekeeper courses. Being conducted
in materials science, robotics, and bioinformatics, guided inquiry laboratories
are designed to make students active learners and to improve their research
laboratory skills by engaging them in interdisciplinary laboratories. For example, in the materials science inquiry-based laboratories students develop real life
materials in the area of composites and sports materials. A full two weeks are devoted to materials
sciences. These laboratory exercises
were developed by funding from DoD 46427-MS. In the robotics laboratory, inquiry
in science is facilitated by informed design.
Students have to design robots from the Lego MindStorms Education NXT
system and program them to accomplish a task with a real world
application. The students are required
to conduct a literature search on their chosen problem, present a formal power
point presentation and compete in a robotics competition. This gives students experience with
open-ended problems.
Each week of the program, students participate in
weekly field trips to scientific research facilities (i.e. GT, CAU, Morehouse, and Spelman) and attend at least two
dynamic research seminars presented by scientists, faculty and upper level
undergraduate or graduate students. The personal and professional development
component of the program is designed to promote scientific literacy which
consists of case studies, an inquiry based understanding of a scientist
identity, lectures on careers in science, seminars on the nature of scientific
research, resume writing, time management workshop and the Birkman Assessment
behavioral tool that points out to the students their personal and professional
interests and strengths.
Outcomes
expected for this Program include giving pre-freshmen practice in the
scientific process, creative thinking, logical thinking, inquiry based skills,
problem solving skills and team work. At
present, the selection of the participants is in progress and the program will
be held on June 7 to July 17. The high
school teachers will participate in every activity (as a teacher’s assistant),
learn each component and incorporate components in their high school lessen
plan as appropriate.
Education Plans for the Coming
Year: It should be noted that the Pre-Freshman Bridge Summer Program
for the summer of 2010 is supported by NSF Historical Black Colleges and
Universities Undergraduate Program grant (0505145). After this summer, PREM will support the
Pre-Freshman Bridge Summer Science Program for students at Morehouse College,
Spelman College and Clark Atlanta University.
High school teachers who participated in the 2010 PREM Teacher Training
Program at Morehouse
College will be given an
opportunity to participate in research projects at Georgia Tech in 2011 as PREM
teachers. The Education Internal
Advisory Committee will continue to have regular meetings in 2010 and 2011 to
assess outcomes and make course corrections as required to fulfill the objective
of this PREM grant.
For PREMs that support Postdoctoral Researchers, describe
the current PREM-wide Postdoctoral mentoring activities and planned activities
for future years.
5. Tables of PREM
Graduates
N/A
As this is the starting year of the PREM project, there are
no PREM Graduates available.
6. List of
Publications
- List
work actually published in this reporting period resulting from PREM
support. Do not include submitted or
accepted papers. Indicate PREM
faculty in bold face and post-docs,
graduate students, and undergraduate students in underline. List patents, if appropriate, and
indicate whether a patent is in pending, granted or licensed.
Alexis Nduwimana and Xiao-Qian Wang,
“Core and Shell
States of Silicon Nanowires under Strain”, J.
Phys. Chem. C 114, 9702–9705 (2010).
O. O. Ogunro and X.-Q. Wang, “Charge Transfer in Noncovalent
Functionalization of Carbon Nanotubes” New
J. Chem, 34, 1084 (2010).
O. O. Ogunro,
K. Karunwi, I. M. Khan, and Xiao-Qian
Wang, “Chiral Asymmetry of Helical Polymer Nanowires”, J. Phys. Chem. Lett. 1, 704 (2010).
W. Yi, A. Malkovskiy,
Y. Xu, X.-Q. Wang,
A. P. Sokolov, M. Lebron-Colon, M. A. Meador, and Y. Pang, "Polymer conformation-assisted wrapping of single-walled carbon nanotube: The impact of cis-vinylene
linkage", Polymer
51,475-481 (2010).
Kelvin Suggs
and Xiao-Qian Wang, “Structural and Electronic
Properties of Carbon Nanotube Reinforced Epoxy Resins”, Nanoscale 2, 385 (2010).
Duminda K.
Samarakoon and Xiao-Qian Wang,
“Chair and Twist-Boat Membranes in Hydrogenated Graphene”, ACS Nano 3, 4017 (2009).
7.
List of Presentations
·
List of oral presentation and posters resulting
from PREM support. Indicate PREM faculty
in bold face and post-docs, graduate
students, and undergraduate students in underline.
Presentations (invited talks, contributed talks, and posters):
OUTPUT TABLE
|
Designation
|
Number
Current Year
|
Cumulative Totals for this Award
|
|
All Publications from PREM support
|
6
|
6
|
|
Publications with students/postdocs as co-authors
|
6
|
6
|
|
|
|
|
|
All Presentations from PREM support
|
9
|
9
|
|
Presentations with students/postdocs as co-authors
|
9
|
9
|
|
|
|
|
|
Patents
|
0
|
0
|
|
Awarded
|
|
|
|
Pending
|
|
|
|
Licensed
|
|
|
8. Highlights:
We have submitted
two Highlights in accordance with the instructions.
9.
Budget
a. Statement
of anticipated unobligated funds at the end of the current fiscal year. If the unobligated funds are greater than 20%
of the annual increment, please provide a justification of why previously
received funds have not been spent.
10. Successful Proposals as a Direct
Result of PREM Funding (> $50K/year).
Not available during this reporting period.
