X-ray scattering and spectroscopy study on structural properties of VO2 and perovskite oxides

Abstract

In this thesis, using the various synchrotron x-ray techniques, the behaviors of transition metal oxides were discussed in thermal process. Chapter 1 describes the behavior of the defect in vanadium oxide across the metal insulator transition using the 3-dimentional (3D) x-ray diffraction technique. Chapter 2 describes the same phenomenon by the resonant hard x-ray emission spectroscopy technique, in other words, electron behavior. In Chapter 3, the difference in the diffraction pattern between the M1 phase and the M2 phase in VO2 nanocrystals and the difference in the structure phase transition were investigated. Chapter 4 describes the segregation and strain change in thickness effect and annealing effect for SrTi0.5Fe0.5O3−δ thin films grown on LaAlO3 substrate. Experimental techniques in 3D x-ray diffraction, fitting process for analysis, conversion of reciprocal space in real, and correlation fuction obtained using FFT for diffraction signals are introduced. Also, x-ray reflectivity was used in conjunction with the grazing incidence x-ray flourescence (GIXRF) technique to describe the thin film behavior by adding anomalous x-ray reflectivity fitting obtained from the energy near the absorption edge of the target atom. Additionally, AP-XPS results are added there, and strain is discussed through diffraction. Finally, it describes the simultaneous measurement of atomic and electron behavior across the phase transition section through resonant hard x-ray emission spectroscopy.