Lanthanide (Ln) doping of lead zirconate titanate (PLnZT 4/30/70) thin films was conducted to investigate effects on structural and electrical properties. Films were spin-coat deposited from precursor solutions made using a previously reported "basic route to PZT" chemistry. The remanent polarization (P r ), dielectric constant (⑀), dielectric loss (tan ␦), and lattice parameter values were obtained for each of the doped PLnZT films. Films doped with amphoteric cations (Tb, Dy, Y, and Ho) displayed high P r values, square hysteresis loops, and enhanced fatigue resistance. Smaller radius Ln-doped films display an increased tendency toward (100) orientation in otherwise (111)-oriented films.

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Density-functional theory calculations, ab-initio molecular dynamics, and the Kubo-Greenwood formula are applied to predict electrical conductivity in Ta 2 O x (0 ≤ x ≤ 5) as a function of composition, phase, and temperature, where additional focus is given to various oxidation states of the O monovacancy (V O n ; n=0,1+,2+). Our calculations of DC conductivity at 300K agree well with experimental measurements taken on Ta 2 O x thin films and bulk Ta 2 O 5 powder-sintered pellets, although simulation accuracy can be improved for the most insulating, stoichiometric compositions. Our conductivity calculations and further interrogation of the O-deficient Ta 2 O 5 electronic structure provide further theoretical basis to substantiate V O 0 as a donor dopant in Ta 2 O 5 and other metal oxides. Furthermore, this dopant-like behavior appears specific to neutral V O cases in both Ta 2 O 5 and TiO 2 and was not observed in other oxidation states. This suggests that reduction and oxidation reactions may effectively act as donor activation and deactivation mechanisms, respectively, for V O 0 in transition metal oxides.

The fabrication of nanoporous thin-film membranes from block polym ers is proposed. A computational modeling effort is described, which optimizes the polymer block lengths in order to obtain therm odynamically favorable phase-separated morphologies. Synthetic rout es to access po ly(ethylene oxide) and p oly (methyl methacrylate)-based block polymers are outlined. These materials were then prepared using controlled free rad ical polymerization. The relative adv antages and disadvantages of numerous routes are discus sed. Characterization of di-and triblock polymers using nuclear m agnetic resonance spectroscopy and size-exclusion chromatograph revealed less than id eal re-initiation and cha in growth o f macroinitiators. Preliminary phase-behavior of these materials is reported from smallangle x-ray scattering and scanning electron microscopy. 4 ACKNOWLEDGMENTS Sandia National Labora tories is a multi-p rogram laboratory managed and opera ted by Sandia Corporation, a wholly owned subsidiary of Lockheed Mar tin Corporation, for the U.S. Department of Energy's Nationa l Nuclear Security Adm inistration under contract DE-AC04-94AL85000.