| Following the first experiments by Sizoo and Onnes in 1925 on Sn, studies of superconductivity under high pressures have made important contributions by furthering our understanding of this exotic state and allowing the discovery of many new and novel superconducting materials, including O, Si, Fe, I, and Cs. Indeed, the number of elemental superconductors across the periodic table has almost doubled through the application of extreme pressures. MgB 2 exhibits the highest superconducting transition temperature (T c) value of any known binary compound, but values of elemental superconductors under extreme pressures are not far behind. In this thesis I present the results of pressure-induced superconductivity on pure elements and compounds using resistivity and ac magnetic susceptibility techniques. Tc of Sc reaches 19.6 K at 107 GPa, the second highest value observed for any elemental superconductor. At higher pressures a structural phase transition occurs causing a drop in Tc to 8.3 K at 111 GPa. A further increase in pressure to 123 GPa pushes Tc to 8.9 K. Europium metal is pressurized to 142 GPa in a search for pressure-induced superconductivity. Eu is found to superconduct at approximately 80 GPa with a Tc value of 1.8 K, thereby becoming the 53rd element to superconduct. Tc of Eu increases linearly with pressure to 2.75 K at 142 GPa. Finally, a search for superconductivity has been carried out on a binary compound of Laves phase CaLi2. The compound exhibits superconductivity under pressure with a Tc value as high as 13 K near 40 GPa. X-ray diffraction work done on CaLi 2 reveals the stability of the compound to the highest pressure measured 54 GPa. |
