Oklahoma State University - Tulsa
Oklahoma State University - Tulsa

Raj N. Singh, Sc.D.

Current Research Projects

The following research projects are being pursued in our research group. A list of major facilities is also provided.

A: Nanostructured Materials:

Diamond thin films, Boron Nitride Nanotube (BNNT)

High Temperature Electronic Devices Based on Wide Bandgap Thin Films

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High temperature electronics has emerged as a very important area because the dominant silicon electronics provides low reliability or fails to function altogether at elevated temperatures. The transformative objectives of this proposal are to synthesize and characterize thin films of high resistivity (undoped), and p- and n-doped polycrystalline diamond (PCD) and AlN suitable for the fabrication of high temperature electronic devices, and to investigate applications/demonstrations of these films in the fabrication of high temperature microelectronic devices where silicon devices are not useful. To accomplish these goals, a truly interdisciplinary and complementary team consisting of Profs. Singh and Kosel from University of Cincinnati (UC) and their students have been working on this project.


Synthesis of BNNTs using MPCVD showing long and interconnected 3-D BNNT arrays.

Synthesis of BNNTs using MPCVD showing long and interconnected 3-D BNNT arrays.

In addition, we are engaged in the synthesis and applications of Boron Nitride Nanotubes (BNNTs).  In contrast to CNTs, boron nitride nanostructured materials, a III-V compound with similar hexagonal structure to graphite, have more uniform electronic properties with a larger band gap (~5.8eV) and are transparent.The primary objective of this project is to perform a fundamental research to synthesize Boron Nitride Nanotube (BNNT) with interconnected 3D networks with excellent, controllable, and predictable electrical properties useful for fabricating electronic devices for sensing/detecting chemical species at room and high temperatures. Instead of the aligned 1D architecture, the BNNTs with novel 3D truss-like network architectures are easier to handle, cost-effective, and expected to impart their unique 1D properties into 3D thereby opening new possibilities for their applications in nanoelectronics, medicine, energy systems, shielding and reinforced-composites.

B: Thermal Management

Diamond Thin Films for Thermal Management of Electronics

Nanocrystalline Diamond Films for Thermal Management

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Heat dissipation in high performance microprocessors and power semiconductor devices is a critical challenge facing the microelectronics industry. One of the most effective ways to remove heat from integrated circuits (ICs) is to use materials with high thermal conductivity in contact with ICs. Therefore, a high thermal conductivity material, especially diamond with the highest thermal conductivity of any known materials, is promising for thermal management of ICs. However, only limited attention has been paid to the study of a recent development, viz., nanocrystalline diamond (NCD) for heat dissipation applications, and totally missing is the pursuit of the transformative layered NCD/microcrystalline diamond (MCD) thin films. Smoothness of the NCD and high thermal conductivity of the MCD prompt us to investigate layered NCD/MCD films towards unusual thermal properties for developing cost-effective thermal management solutions. Therefore, the transformative objective of this program is to understand the mechanisms of thermal transport in NCD and layered NCD/MCD thin films and to use NCD and MCD to reduce thermal interface resistance.

C: Fuel Cells

Electrode, Electrolyte and Self-repairable Sealing Materials for SOFC

High Temperature Sealing Materials that Self Repairs

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Glasses are used as sealing materials in a myriad of technological applications including in energy systems such as seals for Solid Oxide Fuel Cell (SOFC). However, glasses suffer from cracking because of their inherent brittleness when exposed to thermal transients. Recently, our group has advanced and demonstrated the promise of a transformative concept of self-healing/self-repairable glasses as seals for SOFCs. However, a fundamental understanding of the kinetics and mechanism of crack healing in glasses and glass-ceramic composites is currently lacking. In particular, the role of the crystalline ceramic phase in a glass matrix in influencing crack healing behavior is totally unexplored. Therefore, the primary focus of this program is a basic investigation of the crack-healing mechanism and kinetics in promising glass and glass-ceramic composites displaying self-repair in order to further advance this transformative concept of self-repairable seals for SOFCs

Electrode and Electrolytes for SOFCs:

Research is on electrolytes such as scandia-doped zirconia as electrolyte for use in SOFC at lower temperatures and sulfur tolerant anodes. In addition, cathode material of LSF has been investigated. In each of these areas we are engaged in processing and characterization of their electrical properties and performance in SOFCs.

D: Energy Storage Materials

Materials for Li-Ion and Na-S Batteries

Li-ion batteries are extensively used in cell phones, computers and are promising for energy storage in automobiles. While these batteries have performed well in portable electronic devices, significant improvements in performance, capacity, cost and life are needed to make these useful for widespread applications in automobiles and energy storage from wind and solar generators. One way to enhance capacity and performance of Li-batteries is to use novel nanostructured materials as promising electrodes and arranging them in such a way as to enhance capacity and performance. We are pursuing these approaches by taking advantage of our expertise in synthesizing nanostructured materials at Oklahoma State University (OSU). Similarly, new cell configurations are being explored to enhance capacity, performance and reduce cost of the Na-S batteries.

E: Biomaterials

Nanomaterials for Drug Delivery and Biocompatibility/functionalit

Biomaterials are extensively used in medical devices and systems. There is also enhanced interest in using materials in drug delivery. In particular, applications of nanomaterials for drug delivery are exciding for treating cancer as well as delivering drugs locally for a myriad of medical treatments. We are exploring use of nanoparticles for these possible applications in collaborations with faculty from the OSU-Medical School.

F: Composites

High Temperature Ceramic Composites Processing and Properties

Our group has done extensive research and technology developments over the past 25 years related to ceramic matrix composites (CMCs) for applications in high temperature systems such as jet engines and power generation gas turbines. Currently, some of these technologies are being commercialized by industry such as GE. We are engaged in exploring new applications of CMC's in technologies related to Nuclear Reactors and Space Power Systems. The emphasis of research in this area is on processing and high temperature mechanical properties of CMCs.

G: Electrical Ceramics

Piezoelectric and ferroelectric ceramics such as PZT are exposed to electric field in service, which can lead to degradation by crack growth and aging. Our interest in this area revolves around the study of crack growth by applied electric field and exposure to environment. In addition, new material compositions displaying higher strain capability and displaying electric field-induced phase change are being synthesized and their electrical and electromechanical properties are being explored.