Date of Degree


Document Type


Degree Name





Stephen P. O'Brien

Subject Categories

Chemistry | Electrical and Electronics | Mechanics of Materials


Materials science is an interdisciplinary field investigating the structure-property relationship in solid-state materials scientifically and technologically. Nanoscience is concerned with the distinctive properties that matter exhibits when confined to physical dimensions on the order of 10-9 meters. At these length scales, behaviors of particles or elaborate structures are often governed by the rules of quantum mechanics in addition to the physical properties associated with the bulk material.

The work reported here seeks to employ nanocystals, binary nanocomposites and thin films of materials, to build versatile, functional systems and devices. With a focus on dielectric, ferroelectric, and magnetoelectric performance, a series of materials has been synthesized and different types of nanocomposites have been built. Barium strontium titannate particles at various sizes was developed, aiming at high dielectric constant and low loss at high frequency range. Cobalt ferrite-polymer nanocomposite was fabricated with potential magnetoelectric coupling. Along with synthesis, advanced electron microscopies (TEM, SEM, STEM, EELS) at atomic resolution were employed to thoroughly investigate the crystallinity, morphology and composition. By means of spin-coating and printing techniques, single and multiple layered capacitors featuring improved dielectric performance (high k, low loss, high breakdown voltage, etc.) were developed through a) electrode deposition, b) dielectric layer deposition, and c) parylene evaporation. Such capacitors are further incorporated into electric power converters for LED lighting. Hopefully in the future we can make electronic devices more efficient, sustainable, smaller and cheaper.

By advancing our knowledge of nanomaterials, especially those with potential of multifunction, energy efficiency and sustainability, we have strived to push the limits of synthesis, characterization, fabrication and property analysis of nanostructures towards new, reliable and low-cost multifunctional systems. Some of our efforts are described in the following chapters.