Materials Literature
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An integral equation theory is developed for the structure and thermodynamics of melts of random copolymers. The molecules are modeled as flexible chains with a random sequence of two types of sites, with square well potentials between sites. The polymer reference interaction site model (PRISM) integral equation theor…
Recent experiments indicated that the formation of small, nonstoichiometric clusters Zn(n)S(m) and Zn(n)S(m)+ was possible. In this work, the ground states of these clusters, where 1 < or = n, m < or = 4, were studied using density functional theory. Global minima were found to be primarily cyclic structures in which…
Abstract The structural evolution during uniaxial stretching of poly(vinyl chloride) films was studied using our real time spectral birefringence stretching machine. The effect of clay loading and the amount of plasticizer as well as the rate effects on the birefringence development and true mechanical response are pr…
Syndiotactic polystyrene (sPS) is a semicrystalline polymer for which several crystalline structures can be obtained. Cold crystallization of an amorphous sPS sample results in the formation of the α-phase, for which a close packing of the chains is hindered by the phenyl rings. This results in the unusual situation t…
The precursor phases of ${\mathrm{SrFeO}}_{3\ensuremath{-}x}$ (SFO) and ${\mathrm{SrMoO}}_{4}$ (SMO) were used to prepare ${\mathrm{Sr}}_{2}{\mathrm{FeMoO}}_{6}$ with different ratios by a solid-state reaction technique. An x-ray diffractometer was used to identify the phases. SMO was observed to exist in the Mo-rich…
Several synthesis strategies used to obtain hydrothermally stable and highly active catalysts based on ordered mesoporous materials are reviewed in this contribution. It is experimentally observed that the use of zeolite precursors as building blocks of the mesoporous network yields the most stable materials. However,…
A new polyoxovanadate species formulated [V 16 O 42 ] 4– was isolated in DMF solvent. Its structure was solved at 100 K by single-crystal X-ray diffraction in the centrosymmetric monoclinic C 2/ c (no. 15) space group with lattice parameters a = 25.554(6) Å, b = 14.227(3) Å, c = 28.485(6) Å, β = 113.21(1)°, V = 9518(4…
The topology of crack tips in soda–lime–silicate glass was investigated using atomic force microscopy (AFM). Studies were conducted on cracks that were first propagated in water and then subjected to stress intensity factors either at or below the crack growth threshold. Exposure to loads at the crack growth threshold…
Complexation of a CuI ion in a mercuramacrocycle demonstrates the potential of metal–metal interactions in a preorganized system to trap metal ions. The molecular structure of the CuI complex is presented and shows Hg⋅⋅⋅Cu heterometallic and Hg⋅⋅⋅Hg homometallic d10⋅⋅⋅d10 interactions (see figure).
Microphase separation and morphology of thin films of ABC triblock terpolymers are studied with a self-consistent-field theory. Thin films of poly(styrene)- block -poly(2-vinylpyridine)- block -poly( tert -butyl methacrylate) (SVT) triblock terpolymers are modeled as A 3 B 4 C 12 Gaussian chains confined in a slit. Th…
Undoped and Al-doped ZnO films with dopant concentrations of nominally 1% and 10% and a thickness of 100 nm have been grown on ${\mathrm{SrTiO}}_{3}(001)$ by pulsed laser deposition at substrate temperatures between 650 \ifmmode^\circ\else\textdegree\fi{}C and 820 \ifmmode^\circ\else\textdegree\fi{}C. The epitaxial co…
It has been known that simply mixing single-walled carbon nanotubes (SWCNTs) in an aqueous solution of gelatin disperses SWCNTs well for a period of months. Gels made from the gelatin-SWCNT mixture are also stable and have a clear, black color. Scanning electron microscopy shows that gelatin molecules self-organize in…
ABSTRACT Load‐controlled fatigue tests were performed at 20 and 50 °C using two relative humidity levels of 55 and 80% to characterize the influence of humidity and temperature on the fatigue behaviour of an extruded AZ61 magnesium alloy. Fatigue tests were also conducted at 150 °C. No significant variation in fatigue…
We report a study of electronic excitations in manganites exhibiting a range of ground states, using resonant inelastic x-ray scattering (RIXS) at the Mn K edge. Excitations with temperature dependent changes correlated with the magnetism were observed as high as 10 eV. By calculating Wannier functions, and finite-q r…
ABSTRACT This paper presents the results of investigation of a nuclear reactor pressure vessel steel 15Kh2MFA of two strength levels under cyclic loading. The mechanism of microcrack formation on the surface and in the bulk of 15Kh2MFA steel under cyclic deformation was investigated. Analysis of the specimen surfaces…
The electrical conductivity and thermoelectric power of an uranium dioxide single crystal were measured between 908 and 1697 K and for P O2 included between 10 −24 atm and the boundary UO 2+ x /U 4 O 9 . For T <1273 K and near stoichiometry, the electrical conductivity versus P O2 shows a plateau characteristic of…
We report on the thin film phase behavior of poly(styrene)- block -poly(2-vinylpyridine)- block -poly( tert- butyl methacrylate) triblock terpolymers with volume fractions φ PS:φ P2VP:φ PtBMA scaling as 1:1.2: x, with x ranging from 3.05 to 4. On controlled annealing in the vapor of a nearly nonselective solvent the f…
The simple approach of UV-induced coupling of 4-vinylbenzyl chloride (VBC) with the hydrogen-terminated Si(100) (the Si−H) surface provided a stable Si−C bonded initiator monolayer (the Si−VBC surface) for the surface-initiated atom transfer radical polymerization (ATRP). Well-defined polymer−Si hybrids, consisting of…
The treatment of CdSe nanocrystals (NCs) in a 3-amino-1-propanol (APOL)/water (v/v = 10:1) mixture at 80 degrees C in the presence of O(2) causes them to undergo a slow chemical etching process, as evidenced by spectroscopic and structural investigations. Instead of the continuous blue shift expected from a gradual de…
The optical properties of single-crystalline α-Si3N4 nanobelts synthesized via catalyst-assisted pyrolysis of polymeric precursor were characterized by absorption, photoluminescence (PL) and photoluminescence excitation (PLE). The optical absorption spectrum showed that the nanobelts exhibited indirect absorption beha…