Investigation of Local Structures in Cation-Ordered Microwave Dielectric a Solid-State Nmr and First Principle Calculation Study
Doctor of Philosophy (Ph.D.)
Gina L. Hoatson
Solid-state Nuclear Magnetic Resonance (ssNMR) spectroscopy has proven to be a powerful method to probe the local structure and dynamics of a system. In powdered solids, the nuclear spins experience various anisotropic interactions which depend on the molecular orientation. These anisotropic interactions make ssNMR very useful as they give a specific appearance to the resonance lines of the spectra. The position and shape of these resonance lines can be related to local structure and dynamics of the system under study. My research interest has focused around studying local structures and dynamics of quadrupolar nuclei in materials using ssNMR spectroscopy. Li and Nb ssNMR magic angle spinning (MAS) spectra, acquired at 17.6 and 7.06 T, have been used to evaluate the structural and dynamical properties of cation-ordered microwave dielectric materials. Microwave dielectric materials are essential in the application of wireless telecommunication, biomedical engineering, and other scientific and industrial implementations that use radio and microwave signals. The study of the local environment with respect to average structure, such as X-ray diffraction study, is essential for the better understanding of the correlations between structures and properties of these materials. The investigation for short and medium range can be performed with the use of ssNMR techniques. Even though XRD results show cationic ordering at the B-site (third coordination spehere), NMR spectra show a presence of disorder materials. This was indicated by the observation of a distribution in NMR parameters derived from experimental Nb NMR spectra and supported by theoretical calculations.
© The Author
Kalfarisi, Rony Gustam, "Investigation of Local Structures in Cation-Ordered Microwave Dielectric a Solid-State Nmr and First Principle Calculation Study" (2017). Dissertations, Theses, and Masters Projects. William & Mary. Paper 1516639864.