Abstract
In this thesis our main objectives are to study the correlation between pressure and physical properties of materials that show interesting behavior. Temperature and pressure are two variables we used in this study as they are important parameters to better understand material characteristics. A major accomplishment in this study is the development of a high pressure specific heat system that utilizes a Diamond anvil cell together with the thermal relaxation method so that we can study small sample in the order of milligram. Using this high pressure specific heat system, we observed that the Neel temperature of CeAl2 increases with increasing pressure. It is known nanoparticle can generate relatively large internal strain due to the surface effect and may change its physical properties. It is thus interesting to find out how the YBCO superconductor behaves if it is in nanoparticle form. We have fabricated with nanoparticle YBCO using pulsed laser deposition method. We found that for YBCO nanoparticles of sizes: 5nm, 35nm, and 70nm, their superconducting transition temperature remain to be ~ 90 K, however, the superconducting volume fraction is much reduced. For 70nm particle the volume fraction is ~ 1.5%, and for 5 nm only 0.25%. The critical field Hcl also decreases with size from 450 Oe for 70 nm particle down to 170 Oe for 5 nm.