Materials Literature
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The layer structure in the antiferroelectric, ferrielectric, and ferroelectric phases of a liquid crystal device is reported, together with its electric field-induced deformation. The field-free chevron angle is comparable to the steric tilt angle, but differs significantly from the optical tilt angle. A sharp field t…
A boron-rich sodium boride, formerly known as NaB15, has been subjected to a comprehensive structural reinvestigation using X-ray single-crystal and powder diffraction, low-temperature neutron and electron diffraction, high-resolution transmission electron microscopy, and 23Na solid-state NMR spectroscopy. The results…
A variety of metal complexes of 5,10,15-triphenyl-21-monooxa-corrole 4 have been investigated. This monooxa corrole, where one of the pyrrole ring is replaced by a furan moiety, is synthesized by the alpha-alpha coupling reaction of 16-oxa tripyrrane and dipyrromethane. The single crystal X-ray structure of 4 indicate…
Recent experiments have demonstrated that block copolymers are capable of stabilizing immiscible homopolymer blends producing bicontinuous microemulsion. The stability of these polymeric alloys requires the copolymer to form flexible, nonattractive monolayers along the homopolymer interfaces. We predict that copolymer…
The crystal structure of scainiite, Pb 14 Sb 30 S 54 O 5 , has been solved from single-crystal X-ray data and refined to an R index of 8.9 % based on 3703 unique reflections. The structure is monoclinic C 2/ m , with cell parameters a 51.996(8), b 8.148(1), c 24.311(4) A, β 104.09(1)°, V 9990(10) A 3 , and with Z = 4.…
We report the controlled deposition of close-packed monolayer arrays of ∼5-nm-diam Au clusters within patterned regions on GaAs device layers, thus demonstrating guided self-assembly on a substrate which can provide interesting semiconductor device characteristics. Uniform nanometer scale ordering of the clusters is a…
Two new structural fragments are present in the crystal structure of the polyphosphide Ag3SnP7: infinite one-dimensional (P7) chains and Ag3Sn tetrahedra (see picture), which interlink the chains and represent a rare example of transition/post-transition metal heteroclusters in a polyphosphide structure.
Functionalized oligopyridine derivatives can organize into disclike, helical, or tetrahedral structures by metal complexation or through hydrogen bonding. The entities formed can self-organize with formation of a variety of novel and quite unusual liquid crystalline phases with various cylinder and cylinder-layer morp…
The influence of the application of a magnetic field (H) on the temperature (T) dependence of heat capacity and isothermal magnetization has been investigated in Gd2PdSi3, a compound ordering antiferromagnetically below (TN=)21 K in zero H. Among other findings, the one to be emphasized is the observation of significa…
In the pursuit of resins that offer a unique combination of properties primarily for high-performance, high-temperature electronic and aerospace applications, oligomers and polymers containing phen...
Selective oxidation of the surface of an ordered alloy requires redistribution of the atomic species in the vicinity of the surface. This process can be understood in terms of the formation and movements of point defects in the compound. On the basis of ab initio density-functional calculation we found both the creati…
Cyanide-bridged iron-iron and iron--cobalt molecular squares of [Fe(II/4)(mu-CN)4(bpy)8[(PF6)4 x 4H2O (1), [Fe(II/2)Co(II/2)(mu-CN)4(bpy)8](PF6)4 x 3CHCl3 x 2CH3CN (2), and [Fe(II/2)Co(III/2)(mu-CN)4(bpy)8](PF6)6 x 2CHCl3 x 4CH3NO2 (3) (bpy =2,2'-bipyridine) were prepared. X-ray structure analyses for 1-3 were perform…
A new class of periodic mesoporous organosilicas (PMOs) with organic groups incorporated inside the channel walls of the material is discussed. In particular, the unique properties and chemistry exhibited by periodic mesoporous methylenesilica, an isoelectronic analogue of periodic mesoporous silica, are highlighted.…
The structural evolution during heteroepitaxial growth of ZnO/sapphire(001) by radio-frequency magnetron sputtering has been studied using real-time synchrotron x-ray scattering. The two-dimensional (2D) ZnO(002) layers grown in the initial stage are highly strained and well aligned to the substrate having a mosaic di…
Vollkommen delokalisierte π-Elektronensysteme liegen in dreifach verknüpften, kondensierten Porphyrinen vor, die durch Oxidation entsprechender Diporphyrine zugänglich sind [Gl. (1)]. In den Produkten ist die elektronische Wechselwirkung stärker als in den einfach verknüpften Diporphyrinen, was sich in intensiveren un…
Three novel Gd chelates containing on their external surface pendant phosphonate and carboxylate groups, which promote the interaction with the positively charged groups of polyornithine and polyarginine, have been synthesized. Their solution structures have been assessed on the basis of 1H- and 31P-NMR spectra of the…
The general structure of violene/cyanine hybrids (see below) is exemplified by tetrakis(4-dimethylaminophenyl)ethene 1(RED) its vinylogue 2(RED) and its diazavinylogue 3(RED). As judged from their cyclic voltammograms and spectroelectrograms, oxidation occurs perfectly reversible by loss of two electrons creating clos…
The molecular and solid state nonlinear optical (NLO) properties of several (phenylazo)-azulenes are investigated. In particular, (4-nitrophenylazo)-azulene (2b) exhibits a quadratic hyperpolarizability (beta(vec)) of 80 x 10(-30) cm5esu recorded at 1.907 microm by the electric field-induced second-harmonic (EFISH) te…
The effect of various substrates on the electrical and electromechanical properties of 100-nm-thick epitaxial 0.9[Pb(Mg1/3Nb2/3)O3]–0.1[PbTiO3](0.9PMN–0.1PT) thin films is investigated. (001) 0.9PMN–0.1PT films are grown on (001)LaAlO3(LAO), (La, Sr)(Al, Ta)O3(LSAT), SrTiO3(STO), and MgO substrates with 40-nm-thick to…
Resonant x-ray scattering was used to investigate electronic fluctuations of the octahedral iron atoms in magnetite. We measured the (002) and (006) "forbidden" x-ray diffraction reflections permitted by the anisotropy of the iron anomalous scattering factor. The energy and azimuthal angle dependencies of these reflec…