Polymer‐Assisted Hydrothermal Synthesis of Single‐Crystalline Tetragonal Perovskite PbZr_0.52Ti_0.48O₃ Nanowires

Abstract

importance of surface energy considerations for explaining polymorphism at small dimensions. [19] The arguments presented here have demonstrated that the length scale at which a solid-state phase change occurs in pentacene films, given by h c , is related to the ratio of the differences between the (001) surface energies and the bulk energies for the two distinct phases. ExperimentalPentacene powder as received from Aldrich was thermally evaporated from a tungsten wire basket onto room-temperature amorphous carbon coated mica substrates under a vacuum of~10 ±5 torr. Films approximately 20 nm in thickness were evaporated at a rate of approximately 1 nm s ±1 . The pentacene films on amorphous carbon were then floated off the mica onto deionized water for collection with copper grids. Low voltage electron microscopy [20] was done on a LVEM5 from Delong Instruments operating in transmission mode at 4.7 kV. HREM was performed on a 400 kV JEOL 4000 EX operating under low dose conditions [21]. The end-point electron dose for destruction of crystallinity in pentacene was determined to be 0.25 ± 0.05 C cm ±2 at 400 kV [22]. Electron diffraction patterns were taken with a dose of 10 ±4 to 10 ±3 C cm ±2 . HREM images were taken with a dose of less than 0.09 C cm ±2 . Typical HREM images were taken at a magnification of 60 000 , a screen current density of 15 pA cm ±2 and an exposure time of 1.4 s. Negatives were digitized using an Imacon Flextight scanner with 5760 dpi resolution. The Cerius 2 v. 4.6 software package from Accelrys was used for modeling of the pentacene structure and simulation of ED patterns. The Dreiding 2.21 force field [17] was used to describe inter-and intramolecular interactions with a Buckingham exponential-6 potential and a simple harmonic oscillator, respectively. The triclinic pentacene lattice parameters and atomic coordinates were directly entered from the experimentally determined crystal structure [11].

Investigation of Embedded Perovskite Nanoparticles for Enhanced Capacitor Permittivities

“…Recent experiments on perovskites accessed the nanoscale region with the growth of nanowires 13,14 and nanoparticles. 15,16 So far, CaTiO 3 has not found its way in the preparation of nanostructured devices.…”

Additive-Assisted Aqueous Synthesis of BaTiO3 Nanopowders

“…15 PAA was also used to promote the growth orientation of lead zirconium titanate (PZT) crystals in combination with poly(vinyl alcohol) (PVA). 16 When the synthesis was assisted by PVA that was adsorbed onto (001) crystalline planes of PZT minimizing the surface energy by hydrogen bonding, PZT nanorods were formed. When PAA is added to the system, the surface energy reduction is further enhanced due to the adsorption of PAA through carboxy group bonds, and nanowires of PZT were obtained when both PAA and PVA were used.…”

“…It was experimentally claimed that some polymers could be preferentially adsorbed on specific crystallographic planes and control the crystal growth kinetics. 15,16 Poly(acrylic) acid (PAA) and polyethylene-oxide-block-poly(methacrylic) acid adsorb on {100} and {110} crystallographic planes of BaTiO 3 and reduce their surface energy. 17 The BaTiO 3 particles formed in the presence of these polymeric species were rounder than those formed without any polymeric additives demonstrating the crystal habit modifier role of these polymers.…”

“…When PAA is added to the system, the surface energy reduction is further enhanced due to the adsorption of PAA through carboxy group bonds, and nanowires of PZT were obtained when both PAA and PVA were used. 16 Another category of additives, which may influence the growth kinetics and so control the final morphology includes the surfactants. In general, surfactants can influence the growth in two ways: (i) by creating direct micelles (oil in water) the surfactant acts as a growth inhibitor, 18 and (ii) as a capping molecule, they can adsorb on specific crystallographic faces, affecting the growth kinetics, and modifying the crystal shape.…”

Erratum: Fabrication of Ca, Zr doped BaTiO3 ferroelectric nanofibers by electrospinning

“…1 Introduction Low dimensional nanostructured ferroelectric materials such as nanowires, nanofibers and nanoribbons have attracted extensive interest since they can be used as essential parts in nanoelectronic and nanophotonic devices [1][2][3]. Electrospining method to fabricate ultra-thin threads was patented in 1934 [4] and since mid1990s was proved as a versatile technique to produce different high aspect ratio nanofeatures including nanofibers and nanotubes [5].…”