Materials Literature
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The results of studies on the structures of more than 50 new crystals of germanates, gallates, borogermanates, borates, and silicates, possessing laser, piezoelectric, ferroelectric, and ion-conducting properties, are presented. The structure-property relations are considered. The bibliography includes 71 references.
The experimental results, band structure calculations, and theoretical investigations carried out within the framework of the many-electron models of half-metallic ferromagnets (HMFs) are reviewed. These materials have an energy gap for one of the spin projections at the Fermi level and represent a separate class of s…
Abstract The kinetics of phase‐transfer catalyzed free‐radical polymerization of acrylonitrile (AN) was carried out with water‐soluble initiator peroxomonosulphate (PMS) with phase‐transfer catalysts (tetrabutylammonium chloride and benzyltributylammonium chloride (TBAC and BTBAC) in tolune/water two‐phase systems in…
Abstract High T g polyimides containing pendant phenolic hydroxyl groups were synthesized in high molecular weight via one‐step solution polymerization of the dihydrochloride salt of 4,6‐diaminoresorcinol with various commercially available dianhydrides. Polymerization proceeds via initial dissociation of diaminoresor…
Abstract Thermotropic copolyester fibers of oxynaphthoate and oxybenzoate have been subjected to conditions that promote solid‐state polymerization as well as annealing. The annealing process causes the crystals to perfect with a simultaneous increase in heat of fusion and melting temperature. Solid‐state polymerizati…
Abstract Siloxane urethane block copolymers were prepared with siloxanes as the soft segment. Films were cast from a variety of solvents. Solvent has an effect on the segregation of soft and hard segments. Surface studies, including ESCA, EDS, and FT‐IR, show well segregated block copolymers with enhanced siloxane on…
Abstract The copolymers containing photoreactive 4‐methyl coumarin pendant groups have been prepared by radical copolymerization of N ‐(1‐phenylethyl)acrylamide (M 1 ) and 7‐acryloyloxy‐4‐methyl coumarin (M 2 ) in DMF at 70°C. The monomer reactivity ratios (MRR) of M 1 and M 2 are estimated by Finenam‐Ross, Kelen‐Tüdo…
An internal or external electric field F can drive the chemical structure, bond order alternation, and electronic structure of linear polymethine dyes from a neutral, bond-alternated, polyene-like structure, through a cyanine-like structure, and ultimately to a zwitterionic (charge-separated) bond-alternated structure…
The concept of a spatial-velocity hodograph is introduced to describe quantitatively the extrusion of a carbon tubule from a catalytic particle. The conditions under which a continuous tubular surface can be generated are discussed in terms of this hodograph, the shape of which determines the geometry of the initial n…
Ba-rich phlogopite occurs in nephelinite from Komorni hurka (Kammerbuhl), Czech Republic. The mica usually forms euhedral microphenocrysts and subhedral groundmass crystals. Its BaO content ranges from 13 to 16 wt%, at about 5 to 6 wt% TiO 2 . The average mineral formula is (Ba 0.48 K 0.46 Na 0.04 (Ca 0.02 )(Mg 2.22 F…
Microstructure of porous silicon (PS) was observed through high-resolution transmission electron microscope to study a relationship between the microstructure and a photoluminescence (PL) from PS. Three PS samples were made through anodization with different current densities. The samples had different PL spectra and…
NdNiO 3 has been prepared using a low-temperature low-oxygen-pressure method. This compound has the same crystallographic structure as its homologous NdNiO 3 synthesized at high oxygen pressures. The sample obtained shows a metal-insulator transition at around 205 K with a large thermal hysteresis. The metallic phase…
Abstract The cure process and the mechanical properties of blends of diglycidyl ether of bisphenol‐A–based epoxy resin and hydroxyl terminated, internally epoxidized polybutadiene rubber have been studied. Internal oxirane groups are characterized by a main absorption at 885 cm −1 in the infrared spectrum while the te…
Cd1−xYxSb2O6 thin films were deposited onto a silica glass substrate by rf sputtering method. The highest conductivity observed for Cd0.95Y0.05Sb2O6 thin films was 4.1×10 S cm−1, with a carrier concentration of 1.3×1020 cm−3 and a Hall mobility of 1.9 cm2 V−1S −1. No distinct optical absorption band was observed from…
We have performed an in-depth correlation-crystal-field (CCF) analysis of the energy-level structures in 10 Nd 3+ (4f 3 ) crystal systems: NdF 3 , Nd 2 Te 4 O 11 , NdVO 4 , NdPO 4 , Nd 3+ :LiYF 4 , Nd 3+ :LaVO 4 , Nd 3+ :LaCl 3 , Nd 3+ :BaY 2 F 8 , Nd 3+ :YAlO 3 and Nd 3+ :LuA1O 3 . A model Hamiltonian employing 20 fr…
Crystalline and stoichiometric KNbO3 thin films have been grown on (100) oriented MgO substrates by pulsed laser deposition technique. Electron microprobe analysis and Rutherford backscattering spectroscopy of the films show a progressive loss of K with increasing substrate-target distance. To compensate for this K lo…
We have measured the full two-photon absorption (TPA) spectrum in the transparency range of single-crystal polydiacetylene paratoluene-sulfonate (PTS) using $z$ scan. The spectrum consists of three well-defined two-photon excited states superimposed on a continuum of even-parity states. Comparison of the TPA and the o…
Abstract The thermal degradation of polyurethane is exothermic in nature. The addition of CaCO 3 inverts the exothermicity to endothermic behavior in the presence of air. © 1994 John Wiley & Sons, Inc.
The incorporation of nitrogen in diamond films and its effect on film growth were investigated. The nitrogen doping efficiency was found to be very low, consistent with a model of film growth involving simultaneous deposition and etching, which predicts a doping efficiency of 10−4. The growth habit was found to change…
We measured dendritic tip velocities in pure succinonitrile (SCN) in microgravity, using a sequence of telemetered binary images sent to Earth from the space shuttle Columbia (STS-62). Growth velocities were measured as a function of the supercooling over the range 0.05-1.5 K. Microgravity observations show that buoya…