Education
University of MarylandCollege Park, MD
Ph.D. in Materials Science and Engineering, August 2007
Thesis: Combinatorial Investigation of Magnetostrictive Materials
Electronic copies available at
Thesis advisors: Professor Ichiro Takeuchi, Professor Manfred Wuttig
(GPA 3.76 / 4.00)
Rowan UniversityGlassboro, NJ
B.S. in Physics & B.S. in Mathematics, May 2002
(Magna cum laude)
Current N.I.S.T. position
National Institute of Standards and Technology2007-Present
National Research Council Fellow
Research Project
Development of combinatorial in-situ measurement techniques to monitor the absorption/desorption of hydrogen in hydrogen storage materials. The particular emphasis is on being able to spatially map the sorption properties of thin-film composition spread samples via optical techniques such as IR emissivity, F.T.I.R., and Raman spectroscopy. The goal is to render these techniques quantitative by calibrating them with an absolute measurement of the hydrogen present in the sample with a technique such as Prompt Gamma Activation Analysis (PGAA). PGAA is a direct measurement of the presence of hydrogen in a sample, which is done by bombarding the sample with neutrons and monitoring the gamma particles that are emitted as a function of energy.
My particular expertise is in the development of combinatorial samples and their characterization techniques. Library design is a key aspect of combinatorial material science; careful consideration must be given to the physical property being measured and the method by which the property is to be measured. For instance, when measuring the resistance of a gas sensor material in the presence of different gases a larger change in resistance is desired. Therefore it is desirable to deposit individual compositions discretely on top of a pre-patterned device electrode configuration with large areas to maximize S/N. In the case of measuring the dielectric constant of a material in microwave frequency ranges, the measurement can be done with high accuracy and high spatial resolution. Therefore a continuous spread sample covering a large composition region can be deposited. Finally, if the mechanical response of a material under external stimuli (i.e. temperature, magnetic field, etc.) is to be measured then the composition spread sample can be deposited on a thinned wafer, such as a bimorph cantilever array. Here a laser spot can be positioned on the tip of the cantilever and the movement of its reflection can be monitored, allowing the stress state of the material to be determined.
Personal Statement
I have worked in the area of combinatorial materials science for more than 8 years on a variety of materials systems ranging from oxides to metallic materials. My experience covers every stage of combinatorial science such as: library design, thin-film deposition and processing, development of rapid screening techniques, and characterization of samples.
Examples of systems I have worked on include, magnetoelectric PbTiO3-CoFeO4 nanocomposites, Ni-Ti-Cu ideal shape memory alloys, and magnetostriction in Fe-Ga based magnetostrictive materials. To measure the magnetostriction in Fe-Ga, I established a high-throughput measurement technique based on monitoring the position of a reflected laser spot from a bimorph cantilever array as a function of applied magnetic field. Along the way I have written automation software to expedite data acquisition using Labview for a number of measurement techniques, and designed new scanning probe microscopes. One such scanning probe microscope was a magnetic scanning probe microscope, which used a magnetoelectric laminate to detect the AC magnetic field distribution of a current bearing ring.
Research section
The focus of our research is to develop a bench-top characterization technique to rapidly screen thin-film samples for interesting hydrogen storage materials. The bench-top technique would ideally be something that is readily available to most labs; in our case we are focused on the optical properties of the materials as measured by IR emissivity, Fourier Transform Infra-Red spectroscopy, and Raman spectroscopy. These measurements are considered to be in-direct measurements of the hydrogenation status of samples as they measure a secondary property (ie IR emission or its phonon modes).
In order to render these measurements quantitative we are attempting to calibrate the optical response of the material with a direct measurement of its hydrogen content, prompt gamma activation analysis (PGAA). PGAA is a spectroscopic measurement of the mount of hydrogen contained within a sample, the principle of which is to bombard the samples with neutrons and monitor the gammas emitted as a function of energy. By performing the direct and in-direct techniques on identical samples with identical conditions it is hoped that we can establish the limits of detection for the in-direct method, and perhaps eventually quantify the amount of hydride present.
For more information on PGAA please follow these links
The CSTL division website for PGAA
The NCNR website for PGAA
For introductions to Raman and F.T.I.R. spectroscopy