Ultra-small nanocrystals: synthesis, optical and magnetic properties, oriented attachment, and film assembly

Abstract

This dissertation focuses on the colloidal synthesis, and size-dependent optical & magnetic properties of several nanocrystals, such as EuX (X=O, S, Se, Te), Eu2O2S, and Te nanoparticles and nanorods. Significant Néel temperature enhancement and diamagnetic-magnetism transition were observed in EuTe and Eu2O2S nanocrystals, respectively. To better control the synthesis and improve the properties of these materials, the reaction kinetics and growth mechanism of EuS nanocrystals were evaluated using our newly-derived analytical expression for van der Waals interaction between a growing nanorod and an attaching nanoparticle. Towards the application of these nanocrystals, the synthesized nanocrystals were deposited into uniform nano-films using an automatic electrophoretic deposition technique.