The aim of this research is to develop a fundamental understanding of the dominant defect species and the relevant defect equilibrium conditions for bismuth-containing perovskites to help guide the development of these materials for emerging applications. This is of paramount importance for many demanding applications, because ultimately the defect equilibria...
Sensors find a variety of applications in portable electronics, automotive and biomedical solutions. The demand for low power and high dynamic range makes the design of digital sensor readout circuits quite challenging. Traditionally, these circuits are realized using amplifiers with passive feedback or precision analog comparators which are power hungry...
Relaxor characteristic of the solid solution (1-x)BaTiO₃-(x)Bi(Zn₁/₂Ti₁/₂)O₃ (BTBZT) was investigated in this research. X-ray diffraction technique and Raman spectroscopy revealed the crystal structure of BT-BZT at various compositions. For compositions with x ≤ 0.08, the solid solutions exhibited clear tetragonal symmetry and transitioned to pseudo-cubic symmetry as the content of...
The properties of (1-x)BaTiO3-xBi(Mg1/2Ti1/2)O3 (BT-BMT) ceramics were fabricated from reagent-grade ceramic powders by solid-state methods and investigated for solubility, relative permittivity, dielectric loss, polarization, and electromechanical strain. The solubility limit was found to be between x = 0.3 and 0.4. Ba-deficient samples were fabricated, corresponding to stable single-phase compositions; these...
The ternary system (Bi₀.₅Na₀.₅)TiO₃-(Bi₀.₅K₀.₅)TiO₃-Bi(Mg₀.₅Ti₀.₅)O₃ (BNT-BKT-BMgT) was explored along the [75-(x 2) ]Bi₀.₅Na₀.₅TiO₃ - [25-(x 2)]Bi₀.₅K₀.₅TiO₃ - [x]Bi(Mg₀.₅Ti₀.₅)O₃ composition line. Thin films were fabricated using chelated mixing route solutions spin cast onto platinized silicon substrates. Processing parameters such as: excess cation molar%, solution molality, and crystallization temperatures, for composition where x=0,...
Lead zirconate titanate (PZT) is the dominant ferroelectric material in the market due to its excellent piezoelectric properties, relatively high Curie transition temperature (T[subscript C]), low cost, etc. However, because of emerging applications with requirements for high temperature (T[subscript C] > 400 °C) ferroelectrics, researchers are increasingly looking at alternative...
Solid solutions based on the perovskite ferroelectrics Bi₀.₅Na₀.₅TiO₃ (BNT) and Bi₀.₅K₀.₅TiO₃ (BKT) might someday replace current Pb-based ferroelectric and piezoelectric devices. This is one goal of the Restrictions on Hazardous Substances (RoHS) guidelines seeking to limit Pb in consumer devices. Although the Bi-based ferroelectrics are well suited to the task...
Narratives are central to communication and the human experience. For a computer system to understand a narrative, it must be able to identify the key facts or plot elements that describe what happened or how the world has changed. These element are called events;establishing a document’s events and the relationships...
We explore the application of deep learning to the disparate fields of natural language processing and computational biology. Both the sentences uttered by humans as well as the RNA and protein sequences found within the cells of their bodies can be considered formal languages in computer science, as sets of...
This dissertation addresses object recognition in challenging settings, where distinct object classes are visually very similar (e.g., species of birds and insects) and/or access to training examples of object classes is limited (e.g., due to the associated high costs of data annotation). In this dissertation, we present a variety of...