This dissertation, "Molecular Simulation of Transport in Yttria Stabilized-zirconia and Silica Nanopore" by Qingyin, Zhang, 張慶印, was obtained from The University of Hong Kong (Pokfulam, Hong Kong) and is being sold pursuant to Creative Commons: Attribution 3.0 Hong Kong License. The content of this dissertation has not been altered in any way. We have altered the formatting in order to facilitate the ease of printing and reading of the dissertation. All rights not granted by the above license are retained by the author. Abstract: Abstract of thesis entitled MOLECULAR SIMULATION OF TRANSPORT IN YTTRIA-STABILIZED-ZIRCONIA AND SILICA NANOPORE submitted by Zhang Qing Yin for the degree of Doctor of Philosophy at The University of Hong Kong in February 2007 Transport properties in yttria-stabilized zirconia (YSZ) and water confined in a cylindrical silica nanopore were studied by molecular dynamics simulations. Equilibrium molecular dynamics (EMD) and non-equilibrium molecular dynamics (NEMD) were employed to study the transport of oxygen ions in YSZ. The external field imposed on YSZ was either a direct current (DC) or an alternate current (AC) field. Applying the linear response theory in DC-NEMD simulations, the conductivity of oxygen anion was calculated directly by recording the current response. Removing the ohmic heat generated by external field was critical in the NEMD method. Two thermostats, Anderson and Nose-Hoover thermostats were employed in simulations. Both thermostats controlled the temperature of simulation system well. The conductivity obtained by DC-NEMD method was compared with the results of EMD method and experimental results. The Arrhenius activation energies of YSZ was determined in DC-NEMD simulations to be 68 and 66 kJ/mol with Anderson and Nose-Hoover thermostats, respectively, whereas in EMD simulations 57 and 56 kJ/mol with Anderson and Nose-Hoover thermostats, respectively. The results obtained by DC-NEMD agreed better with experimental results. The AC-NEMD method was used to probe the frequency dependent conductivity of YSZ. The YSZ showed capacitance character in low frequency range. With increasing frequency, an inductance character was observed at high frequency. The structures and diffusion behaviour of water confined in a cylindrical silica nanopore were study by EMD method. The diameters of silica pores studied were 4.75 A, 9.51 A, 20 A and 25 A. Due to the confinement effect and hydrophilic nature of silica wall, the diffusion of water in a silica pore was slower than in the bulk phase. The diffusion coefficient of water decreased with decreasing pore diameter. Through the density profile analyses, the water preferred to attach closely to the silica wall. The studies of water confined in silica pore provided a basis for further research of electrolyte confined in a silica nanopore. DOI: 10.5353/th_b3955768 Subjects: Zirconium oxide - Transport propertiesMolecular dynamics