Materials Literature
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Adsorption/reaction kinetics of C2H2 on the surface of plasma-treated SiO2 and TiO2 catalysts is studied. The catalysts are pretreated with a dc discharge in Ar, O2, N2, or air. Then 950 ppm of C2H2 in air is introduced in the closed-volume reactor. It is found that TiO2 pretreated with O2 or air plasma catalyzes C2H2…
The elastic theory of liquid crystals can be traced back to the early 1930s, but the origin of the molecular theory of elastic constants must be postponed to more than 30 years later, when Alfred Saupe wrote his famous papers on this subject. At approximately the same time, the seminal works by Priest and Straley also…
The observation and quantification of the biaxiality in the nematic phase of thermotropic liquid crystals is one of the topical problems in the science of liquid crystals. The biaxiality in the refractive index and/or relative permittivity, both constituting tensors of the second rank, are expressed in terms of the fo…
ZnO particles with an average size of about 5 nm were prepared via a sol-gel chemical route and the silane coupling agent, (3-glycidyloxypropyl)-trimethoxysilane (GPTS), was adopted to enhance the dispersion of the ZnO nanoparticles in ethyl glycol (EG) solution. A ZnO surface potential as high as 66 mV was observed a…
Abstract Novel crosslinked thin polymer networks based on vegetable oil hydroxy fatty acids (HFAs) were prepared by UV photopolymerization and their mechanical properties were evaluated. Two raw materials, castor oil and 7,10‐dihydroxy‐8( E )‐octadecenoic acid (DOD) were used as sources of mono‐ and di‐HFAs, respectiv…
We show that the optical responses of a graphene pn junction is dominated by nonlinear intraband and interband processes. At the experimentally relevant electric field intensity, nonlinear conductance is an order of magnitude larger than the linear conductance. Furthermore, the total conductance is negative in the ter…
A five-ring bent-core unit and a phenyl benzoate moiety are linked together by means of a flexible spacer. Starting from dimers having different length of the aliphatic parts, that is the terminal alkyloxy chains and the spacer, the direction of each of the four ester connecting groups in the bent-core unit is reverse…
We have investigated the possibility of using single-walled carbon nanotubes (SWNTs) as the infrared energy conversion material based on the configuration of SWNT/Si heterojunction. The performance of solar cells based on SWNTs has been examined under illumination by the light with different wavelengths. Our experimen…
Wide-range color tuning from red to blue was achieved in phosphor-free p+-Si/p-CuAlO2/n-ZnO nanorod light-emitting diodes at room temperature. CuAlO2 films were deposited on p+-Si substrates by sputtering followed by annealing. ZnO nanorods were further grown on the annealed p+-Si/p-CuAlO2 substrates by vapor phase tr…
We report the fabrication of a double Schottky barrier (DSB) device by self-assembly of nanowires (NWs). The operating principle of the device is governed by the surface depletion effects of the NWs. High DSBs were formed at the contact interface of ZnO NWs self-assembled into bascule nanobridge (NB) structures. The b…
Dispersions of board-like goethite (α-FeOOH) particles with short-range repulsive interaction form a versatile colloidal model system, showing a nematic, smectic A and columnar phase. In high magnetic fields a biaxial nematic phase is induced with the shortest dimension of the particles aligned along the field. Moreov…
The interface conductance of LaAlO3/SrTiO3 heterostructures was investigated under high temperature oxygen equilibrium. The dependence of the heterostructure’s conductance on oxygen partial pressure (from 10−22 to 1 bar) and temperature (800 to 1100 K) was compared to the characteristic of SrTiO3 single crystals, whic…
A novel pyridine-containing aromatic diamine monomer, 4-phenyl-2,6-bis[3-(4-aminophenoxy)phenyl]pyridine (m,p-PAPP), was successfully synthesized by a modified Chichibabin reaction of benzaldehyde and a substituted acetophenone, 3-(4-nitrophenoxy)acetophenone (m,p-NPAP), followed by a reduction of the resulting dinitr…
High energy ball milling has been shown to be a promising method for large-scale fabrication of rare earth-transition metal nanoparticles. In this work, magnetically hard Nd-Fe-B nanopowders with a coercivity in the range of 1.2-4 kOe have been produced by surfactant-assisted ball milling of nanocrystalline precursor…
Monolayers of PbSe and PbS quantum dots and PbSe/CdSe core/shell quantum dots made by Langmuir-Blodgett deposition are compared, with a focus on the formation, the morphology and the photoluminescence properties of the films. It is shown that PbSe quantum dots suffer from oriented attachment and a complete quenching o…
Through the utilization of element-resolved polarized x-ray probes, the electronic and magnetic state of an artificial La2FeCrO6 double perovskite were explored. Applying unit-cell level control of thin film growth on SrTiO3(111), the rock salt double perovskite structure can be created for this system, which does not…
In 1970, two seemingly unrelated reports about nematic liquid crystals appeared in the scientific literature: at Kent State University, Adrian de Vries reported local smectic order in a nematic that he termed cybotactic, and at IBM, Marvin Freiser showed the possibility of a lower symmetry nematic that he named biaxia…
Linear and quadratic electromechanical effects of liquid crystals are reviewed. Among the linear effects the piezoelectric and flexoelectric effects and their analogues in low molecular weight fluid, nematic, smectic and columnar liquid crystals, in polymeric and elastomer liquid crystals, are discussed and compared w…
The optical reflection contrast and optical transmission contrast of graphitic films on glass ranging in thickness from a monolayer to the limit of bulk graphite have been experimentally measured. For samples with more than 10 graphene layers where optical contrast quantization becomes difficult to observe, atomic for…
The effect of Fe2O3-doping on the defect structure and piezoelectric properties of [Bi0.5Na0.5]TiO3 ceramics is studied by means of electron paramagnetic resonance spectroscopy. The results show that the Fe3+ functional centers are incorporated at the perovskite B-site, and clearly can be attributed to the formation o…