Magnetic Properties of Bismuth Ferrite Nanopowder Obtained by Mechanochemical Synthesis

Multiferroic bismuth ferrite (BiFeO3) nanopowders have been obtained in room temperature by mechanical synthesis. Depending on the post-synthesis processing the nanopowders have exhibited differences in the mean sizes, presence of amorphous layer and/or secondary phases. Extended magnetic study performed for fresh, annealed and hot-pressed nanopowders have revealed substantial improvement of the magnetic properties in the as-prepared powder.Comment: 4 pages, 3 figure

Ferroelectric Nanotubes

We report the independent invention of ferroelectric nanotubes from groups in several countries. Devices have been made with three different materials: lead zirconate-titanate PbZr1-xTixO3 (PZT); barium titanate BaTiO3; and strontium bismuth tantalate SrBi2Ta2O9 (SBT). Several different deposition techniques have been used successfully, including misted CSD (chemical solution deposition) and pore wetting. Ferroelectric hysteresis and high optical nonlinearity have been demonstrated. The structures are analyzed via SEM, TEM, XRD, AFM (piezo-mode), and SHG. Applications to trenching in Si dynamic random access memories, ink-jet printers, and photonic devices are discussed. Ferroelectric filled pores as small as 20 nm in diameter have been studied

Creation of multiple nanodots by single ions

In the challenging search for tools that are able to modify surfaces on the nanometer scale, heavy ions with energies of several 10 MeV are becoming more and more attractive. In contrast to slow ions where nuclear stopping is important and the energy is dissipated into a large volume in the crystal, in the high energy regime the stopping is due to electronic excitations only. Because of the extremely local (< 1 nm) energy deposition with densities of up to 10E19 W/cm^2, nanoscaled hillocks can be created under normal incidence. Usually, each nanodot is due to the impact of a single ion and the dots are randomly distributed. We demonstrate that multiple periodically spaced dots separated by a few 10 nanometers can be created by a single ion if the sample is irradiated under grazing angles of incidence. By varying this angle the number of dots can be controlled.Comment: 12 pages, 6 figure

Fabrication of arrays of lead zirconate titanate (PZT) nanodots via block copolymer self-assembly

This Article presents a simple methodology for the fabrication of two-dimensional arrays of lead zirconate titanate (PZT) nanodots on n-doped Si substrates via the directed self-assembly of PS-b-PEO block copolymer templates. The approach produces highly ordered PZT nanodot patterns, with lateral widths and heights as small as 20 and 10 nm, respectively, and a coverage density as high as ∼68 × 109 nanodots cm–2. The existence of a perovskite phase in the nanodots was confirmed by X-ray diffraction and X-ray photoelectron spectroscopy. The piezo-amplitude and ferroelectric domain response obtained from the nanodots, through piezoresponse force microscopy, confirmed the presence of ferroelectricity in the PZT arrays. Notably, PZT nanodots with a thickness ∼10 nm, which is close to the critical size limit of PZT, showed ferroelectric behavior. The presence of a multi-a/c domain structure in the nanodots was attributed to their polycrystalline nature

Single-crystalline ferroelectric thin films by ion implantation and direct wafer bonding

Layer splitting by helium and/or hydrogen implantation and wafer bonding was applied to transfer thin single-crystalline ferroelectric layers onto different substrates. The optimum conditions for achieving blistering/splitting after post-implantation annealing were experimentally obtained for LiNbO3, LaAlO3, SrTiO3 single crystals and PLZT ceramic. Under certain implantation conditions large area exfoliation instead of blistering occurs after annealing of as-implanted substrates. Small area single-crystalline layer transfer was successfully achieved