Students currently enrolled in the Physics graduate program here at Brock University can submit an electronic copy of their final Major Research Paper to this repository. If you are logged in please click on 'Submit a New Item to this Collection' to proceed. Once your MRP has been accepted in the Repository you will receive an email confirmation along with a link to your work
PREPARATION AND CHARACTERIZATION OF MISFIT CHALCOGENIDE [(SnSe)1+δ]m[VSe2]nThe two-dimensional misfit layer dichalcogenide compounds [(MX)1+δ]m [(TX2)n] consist of alternating stackings of two subsystems of MX (Rock Salt) and TX2 (Transition metal dichalcogenide). Where, M = Sn, Pb, Bi, rare earth; X = S, Se; T = Ti, V, Nb, Ta, Cr. In Misfit layer compound (MLCs), at least one lattice parameter of the two subsystem unit cells should be incommensurate. m and n are integers that determine the stacking arrangement of MX and TX2 layers. As a part of this research, attempts to synthesize single crystal of [(SnSe)1+δ]m [(V Se2)n] using a chemical vapour transport technique with I2 crystals as the transporting agent were carried out. Mixed crystals were formed with thin layers of [(SnSe)1+δ]m [(V Se2)n] present among the other byproduct materials. Monolayer, bilayer, and trilayer misfit layers were observed. The compositions and crystal structure of the misfit layer were investigated by Energy Dispersive X-ray spectroscopy and X-ray diffraction respectively. The parent compound, VSe2 was successfully synthesized as single crystal using the same method. Characteristic MLC vibrational modes were studied via optical Raman spectroscopy measurements and compared to the parent compound, VSe2. At 3.5 K, three characteristic vibrational modes are observed in the XX polarized Raman spectrum: Ag(1), Ag(2), Eg. Based on the observed Ag(1) mode in VSe2, the MLC Ag modes have been shifted. Those Raman frequencies for the intralayer vibrations of the VSe2 layers in the MLC deviate from that of the VSe2 crystals, which may be due to the charge 2 transfer from the SnSe layer to the VSe2 layer. In addition, the polar plots of the intensity of the MLC vibrational modes as a function of XX polarization angle are presented to study the symmetry of the vibrational mode. In comparison with the VSe2 Ag mode, both MLC Ag modes exhibit two-fold polarization anisotropy with a period of 180 degrees. This reveals that the site symmetry of the MLC is altered compared to VSe2.
Raman Spectroscopy of pure and (Nb+In) co-doped TiO2 single crystalsThis research project focused on the study of pure TiO2 rutile crystals and rutile crystals that were 2% co doped with Niobium and Indium TiO2 (2-NITO). There has been a growing interest in co-doped TiO2 due to recent papers published on its “colossal permittivity” in the lower frequency range of 10^2 to 10^6 Hz. The goal of this study was to analyze the impact of co-doping on the Raman modes by using Raman spectroscopy. To determine the Raman shift and Half width at half max from the raman data, the Lorentz fit analysis was applied.