Phase transitions and diffusion of colloid-polymer systems and thin ferroelectric films for device applications
Robert, Marc A.
Doctor of Philosophy
This thesis is divided into two independent parts: the first part deals with the phase transitions and diffusion of colloid-polymer systems, while the second part concerns the growth of thin ferroelectric films, their physical and chemical characterizations, and theoretical predictions for surface-acoustic-wave (SAW) propagation. In the first part, the phase transitions of colloid-polymer systems are studied by experiment and theory in both two and three dimensions. For a colloid-polymer system consisting of polystyrene spheres in aqueous solutions of hydroxyethylcellulose, the transitions are examined experimentally using enhanced videomicroscopy with particle resolution, and the results are compared with statistical mechanical predictions based on the Percus-Yevick and mean-field approximations. The Brownian motion of colloidal particles in polymer solutions is also investigated for the system of colloid (polystyrene)-polymer (polyethyleneoxide), and the diffusivity is determined as a function of polymer concentration. In the second part, thin films of the ferroelectric lithium niobate are deposited by radio-frequency magnetron sputtering on diamond-coated silicon substrates for high-frequency SAW-device applications. The SAW velocity and electromechanical coupling coefficient are predicted theoretically for various film orientations and thicknesses. Moreover, thin films of the ferroelectric barium titanate are deposited on silicon substrates for random-access-memory applications, and their crystal and electrical properties are investigated.
Chemical engineering; Electronics; Electrical engineering; Engineering; Materials science