Abstract: Much attention is drawn to the preparation, structure and properties investigation of lead-free ferroelectrics for the next generation of piezoelectric devices. (Na0.5Bi0.5)TiO3-BaTiO3 (NBT-BT) lead-free solid solution piezoelectric single crystals with composition x in the range of 0–0.05 as a materials with high piezoelectric properties were successfully grown from platinum crucible by using the top-seeded solution growth (TSSG) method. The dimensions of NBT-BT crystal is Ø40 × 10 mm2. X-ray powder diffraction patterns reveal that the crystal structure of NBT-BT crystal changes from rhombohedral to tetragonal symmetry with increasing amounts of BT(x). The dielectric, ferroelectric and piezoelectric properties of NBT-BT crystals with different compositions near the morphotropic phase boundary (MPB) were studied systematically. Ions (Mn, Eu, Zn) doped NBT and NBT-BT 95/5 crystals were also grown and studied. In addition, their piezoelectric and ferroelectric properties are investigated. Further, a high-quality and large-sized (K0.25Na0.75)NbO3 (KNN25/75) single crystal has been achieved by a carefully controlled TSSG method. The dimensions of the as-grown KNN25/75 single crystal reached up to Ø30 × 10 mm2. The obtained KNN crystals provided us a superb material for the dielectric, piezoelectric, ferroelectric and electromechanical coupling property characterization along different orientations.
Abstract: Infrared extinction of a dye-doped (polymer/liquid crystal) composite film was investigated. It is found that doping a metal-complex dye into the liquid crystal extended the operation wavelength to an optical fiber communication wavelength of about 1.5 μm. An aperture placed behind the composite film greatly improves an extinction ratio, which suggests the film functions on the basis of light scattering. Some experimental results agree to Rayleigh scattering. The film exhibits the high extinction ratio of 51 or 17.1 dB and a low polarization dependent loss of 7.6% or 0.32 dB and, then, it could be applied to a telecommunication device such as a variable optical attenuator.
Crystals2015, 5(1), 154-162; doi:10.3390/cryst5010154 - published 16 February 2015 Show/Hide Abstract
Abstract: Recent IUPAC (The International Union for Pure and Applied Chemistry) recommendations on the terminology of metal-organic frameworks are reviewed and the background to a proposed topology classification is discussed. The various numerical designators such as point symbols, vertex symbols and transitivity are also explained and their importance elucidated.
Crystals2015, 5(1), 143-153; doi:10.3390/cryst5010143 - published 16 February 2015 Show/Hide Abstract
Abstract: TEV (Thermal Expansion Visualizing) is a user-friendly program for the calculation of the thermal expansion tensor αij from diffraction data. Unit cell parameters determined from temperature dependent data collections can be provided as input. An intuitive graphical user interface enables fitting of the evolution of individual lattice parameters to polynomials up to fifth order. Alternatively, polynomial representations obtained from other fitting programs or from the literature can be entered. The polynomials and their derivatives are employed for the calculation of the tensor components of αij in the infinitesimal limit. The tensor components, eigenvalues, eigenvectors and their angles with the crystallographic axes can be evaluated for individual temperatures or for temperature ranges. Values of the tensor in directions parallel to either [uvw]’s of the crystal lattice or vectors (hkl) of reciprocal space can be calculated. Finally, the 3-D representation surface for the second rank tensor and pre- or user-defined 2-D sections can be plotted and saved in a bitmap format. TEV is written in JAVA. The distribution contains an EXE-file for Windows users and a system independent JAR-file for running the software under Linux and Mac OS X. The program can be downloaded from the following link: http://www.uibk.ac.at/mineralogie/downloads/TEV.html (Institute of Mineralogy and Petrography, University of Innsbruck, Innsbruck, Austria)
Crystals2015, 5(1), 116-142; doi:10.3390/cryst5010116 - published 13 February 2015 Show/Hide Abstract
Abstract: This report describes extensive studies of deposition processes involving tin oxide (SnOx) nanoparticles on smooth glass surfaces. We demonstrate the use of smooth films of these nanoparticles as a platform for spatially-selective electroless deposition of silver by soft lithographic stamping. The edge and height roughness of the depositing metallic films are 100 nm and 20 nm, respectively, controlled by the intrinsic size of the nanoparticles. Mixtures of alcohols as capping agents provide further control over the size and shape of nanoparticles clusters. The distribution of cluster heights obtained by atomic force microscopy (AFM) is modeled through a modified heterogeneous nucleation theory as well as Oswald ripening. The thermodynamic modeling of the wetting properties of nanoparticles aggregates provides insight into their mechanism of formation and how their properties might be further exploited in wide-ranging applications.
Crystals2015, 5(1), 100-115; doi:10.3390/cryst5010100 - published 12 February 2015 Show/Hide Abstract
Abstract: The crystal and molecular structures of the title compounds, phenyl quinoline-2-carboxylate and 2-methoxyphenyl quinoline-2-carboxylate, two new derivatives of quinolone-2-carboxylic acid, are reported and confirmed by single crystal X-ray diffraction and spectroscopic data. Compound (I), C16H11NO2, crystallizes in the monoclinic space group P21/c, with 8 molecules in the unit cell. The unit cell parameters are a = 14.7910(3) Å; b = 5.76446(12) Å; c = 28.4012(6) Å; β = 99.043(2)°; V = 2391.45(9) Å3. Compound (II), C17H13NO5, crystallizes in the monoclinic space group P21/n with 4 molecules in the unit cell. The unit cell parameters are a = 9.6095(3) Å; b = 10.8040(3) Å; c = 13.2427(4) Å; β = 102.012(3)°; V = 1344.76(7) Å3. Density functional theory (DFT) geometry optimized molecular orbital calculations were performed and frontier molecular orbitals of each compound are displayed. Correlation between the calculated molecular orbital energies (eV) for the surfaces of the frontier molecular orbitals to the electronic excitation transitions from the absorption spectra of each compound has been proposed. Additionally, similar correlations observed among six closely related compounds examining small structural differences to their frontier molecular orbital surfaces and from their DFT molecular orbital energies, provide further support for the suggested assignments of the title compounds.