RUI: Investigation of metal-to-metal charge transfer states in rare earth ion-doped solids

Wheaton College, Norton MA

Investigators

Abstract

NON-TECHNICAL DESCRIPTION: This three-year research project is investigating a promising class of materials for use as lighting and/or laser applications. The materials of interest are oxides containing the rare earth ions praseodymium and terbium, which give off red and green light, respectively. These materials are interesting because there exists a quantum state that allows ultraviolet energy to be put into the system efficiently. Subsequently, that energy can be transformed to red or green light. By changing the composition of the materials, it is possible to alter the characteristics of this quantum state to maximize the energy input and extract light at the desired color. The goals of the project are to: (1) gain insight into the physical and chemical properties of this state, and (2) to optimize the visible light output of these systems for applications to phosphors used in solid-state lighting and in display materials, and for solid-state laser applications. TECHNICAL DESCRIPTION: This three-year research project investigates a charge transfer state of d0 transition metal oxides doped with rare-earth ions (praseodymium and terbium) using the techniques of luminescence spectroscopy. The project includes an experimental study into the fundamental properties of the charge transfer state, and into its role in the dynamics of the relaxation processes that lead to emission from the rare earth ions. The energy of the charge transfer state is being tuned to maximize the luminescence efficiency of the specified rare earth ions. This tuning is being accomplished by changing the composition of the materials and by altering the particle size down to the nm-scale. The project provides significant training to undergraduates, giving them hands-on experience in the laboratory, allowing them to present their work at scientific conferences, and by collaborating with scientists at other universities.