Single crystal

About: Single crystal is a research topic. Over the lifetime, 59617 publications have been published within this topic receiving 870828 citations.

Non-volatile Ferroelectric Poly(vinylidene fluoride-co-trifluoroethylene) Memory Based on a Single-Crystalline Tri-isopropylsilylethynyl Pentacene Field-Effect Transistor

Abstract: A new type of nonvolatile ferroelectric poly(vinylidene fluoride-co-trifluoroethylene) (P(VDF-TrFE)) memory based on an organic thin-film transistor (OTFT) with a single crystal of tri-isopropylsilylethynyl pentacene (TIPS-PEN) as the active layer is developed. A bottom-gate OTFT is fabricated with a thin P(VDF-TrFE) film gate insulator on which a one-dimensional ribbon-type TIPS-PEN single crystal, grown via a solvent-exchange method, is positioned between the Au source and drain electrodes. Post-thermal treatment optimizes the interface between the flat, single-crystalline ab plane of TIPS-PEN and the polycrystalline P(VDF-TrFE) surface with characteristic needle-like crystalline lamellae. As a consequence, the memory device exhibits a substantially stable source–drain current modulation with an ON/OFF ratio hysteresis greater than 103, which is superior to a ferroelectric P(VDF-TrFE) OTFT that has a vacuum-evaporated pentacene layer. Data retention longer than 5 × 104 s is additionally achieved in ambient conditions by incorporating an interlayer between the gate electrode and P(VDF-TrFE) thin film. The device is environmentally stable for more than 40 days without additional passivation. The deposition of a seed solution of TIPS-PEN on the chemically micropatterned surface allows fabrication arrays of TIPS-PEN single crystals that can be potentially useful for integrated arrays of ferroelectric polymeric TFT memory.

Functional organic single crystals for solid-state laser applications

Abstract: Because of long-range order and high chemical purity, organic crystals have exhibit unique properties and attracted a lot of interest for application in solid-state lasers. As optical gain materials, they exhibit high stimulated emission cross section and broad tunable wavelength emission as similar to their amorphous counterpart; moreover, high purity and high order give them superior properties such as low scattering trap densities, high thermal stability, as well as highly polarized emission. As electronic materials, they are potentially able to support high current densities, thus making it possible to realize current driven lasers. This paper mainly describes recent research progress in organic semiconductor laser crystals. The building molecules, crystal growth methods, as well as their stimulated emission characteristics related with crystal structures are introduced; in addition, the current state-of-the-art in the field of crystal laser devices is reviewed. Furthermore, recent advances of crystal lasers at the nanoscale and single crystal light-emitting transistors (LETs) are presented. Finally, an outlook and personal view is provided on the further developments of laser crystals and their applications.

Size controllable synthesis of single-crystal ferroelectric Bi4Ti3O12 nanosheet dominated with {001} facets toward enhanced visible-light-driven photocatalytic activities

Abstract: Highly crystallized single crystal Bi4Ti3O12 nanosheets with dominant {001} facets were synthesized by heating a stoichiometric composition of alpha-Bi2O3 and TiO2 in molten NaCI KCl at 800 C for 2 h. Effects of the amount of the added molten salts (their mole ratio (M) to nominal Bi4Ti3O12 varied from 4 to 60 and the samples were denoted as BTO-M) on the size distribution and photoactivity of the resulting products were systematically evaluated. The side length of as-prepared Bi4Ti3O12 gradually decreases by increasing the addition of molten salts, and the minimal side length is achieved in the sample BTO-50. As a result, the sample BTO-50 shows the best photocatalytic kinetics in photodegradation of rhodamine B (RhB) under visible-light irradiation, which is about 8.65 times faster than that of the sample BTO-0 obtained by a traditional solid-state reaction method, demonstrating the superiority of the present molten salts synthesis for bismuth titanate. The improved photocatalytic kinetics of BTO-M is a concert of several factors including the highly faceted surfaces, thin flakes that shorten the charge transport distance to the surface, as well as the internal electric fields produced by the spontaneous polarization in the BTO-50 sample that facilitate the separation of photoinduced charges as evidenced by Kelvin probe force microscopy. Electrochemical impedance spectroscopy further reveals that under visible-light, the electron transfer resistance of the BTO-50 decreases to nearly 50% of that of the BTO-0 sample. (C) 2014 Elsevier B.V. All rights reserved.

An ultrahigh vacuum single crystal adsorption microcalorimeter

Abstract: The design of an ultrahigh vacuum microcalorimeter enabling calorimetric heats of adsorption to be obtained on single crystal surfaces as a detailed function of coverage is discussed. The system comprises a pulsed supersonic molecular beam source, an ultrathin metal single crystal, and remote infrared temperature sensing. Sticking probabilities and coverages are determined pulsewise by the King and Wells method, and heat capacity calibrations are conducted in situ by laser beam pulsing. Results for CO and O2 on Ni{110} demonstrate excellent sensitivity to adsorption of ∼10−13 moles of gas (∼0.01 monolayer). The heat capacity of the calorimeter is 4.2 μJ K−1.