Materials Literature
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The reduction of NO by CO on Pt has been extensively investigated in the past since it helps to eliminate NO of the exhaust gas of cars. However, the dissociation of NO in this reaction and the deactivation of the NO/CO reaction on Pt-supported catalysts still need to be discussed. In this work, the reduction of NO wi…
Abstract The clay mineralogy of an oxisol-saprolite overlying serpentinite and underlying basalt was studied with different techniques to evaluate the clay mineral transformation that occurred and to understand the origin of Fe 3+ -rich smectite. The saprolite zone of the oxisol, up to 30 m thick, contains smectites o…
Abstract The deuteration technique was used to assign unknown infrared (IR) bands of Ge-bearing talcs. Procedures to achieve partial or complete H/D replacement in synthetic Ge-bearing (Mg, Ni and Co)-talcs have been investigated. From the spectral shift of IR absorption bands in the 4000–300 cm -1 region resulting fr…
This paper reports the Ferroelectric and Piezoelectric properties of lanthanum doped lead barium niobate ceramics with formula Pbx-3y/2 Ba1-x Lay Nb2 O6. Piezoelectric properties showed a strong enhancement at morphotrophic phase boundary between tetragonal and orthorhombic phases. d33 value of 350 pc/N obtained is hi…
A model of the ice proton system taking into account quantum-mechanical tunneling of protons along hydrogen bonds has been formulated and investigated. When the tunneling amplitude is small the quantum ground state of the proton system is degenerate, like the classical ground state. At higher tunneling amplitudes, how…
The room-temperature crystal structure of the B-site ordered complex perovskite strontium ytterbium niobate, Sr(Yb(0.5)Nb(0.5))O(3) [monoclinic, Z = 2, P2(1)/n (set 2), a = 5.79095 (8), b = 5.82210 (7), c = 8.20358 (12) Å, beta = 90.126 (1) degrees, with final R(wp) = 0.0595, R(Bragg) = 0.0203 for the neutron profile…
Abstract The influence of sodium oleate additives on processing and morphology of polypropylene ‐ co ‐polyamide (PP/CPA) mixture melts has been investigated. It is shown that sodium oleate is located in the interphase of the components and acts at small additives (up to 3 wt%) as an interfacial tension agent, improvin…
This study proposes a new approximating formula for calculating gamma-ray buildup factors in multilayer shields. The formula combines the buildup factors of single-layer shields with products and quotients. The feasibility of the formula for reproducing the buildup factors was tested by using point isotropic buildup f…
The structure of a topological dipole (two nematic point defects with opposite charges) is considered theoretically both in an infinite space and in a capillary. It is shown that the Frank elastic energy tends to concentrate within a spheroidal string if the defects are not too far from each other. The string thicknes…
Polysulfone was modified by incorporation of hydrophilic poly(oxy-1,4-butanediyl) [synonyms: poly(tetramethylene ether glycol), PTMG, poly(tetrahydrofuran), poly(THF), poly(tetramethylene oxide)] units into the polysulfone chain resulting in the formation of segmented block copolymers. These block copolymers were prep…
A recently developed method for fitting a Monte Carlo computer simulation model to observed single-crystal diffuse X-ray scattering has been applied to ( hk 0) scattering data obtained for the guest–host system (inclusion compound) cyclohexane–perhydrotriphenylene (cyclohexane–PHTP), C 6 H 12 /C 18 H 30 , at 295 K. A…
Susceptibility to radiation of rare-earth elements and transition metals in Y3Al5O12, YAlO3, LiNbO3, SrGdGa3O7 single crystals was investigated. Additional absorption bands after g-irradiation with doses 103-107 Gy and protons with fluencies of 1013-1016 cm-2 were found. A decrease in additional absorption with increa…
We report 17 O magic-angle spinning (MAS) NMR data for crystalline NaAlO 2 and CaAl 2 O 4 at external magnetic fields of 9.4 and 14.1 T, as model compounds for Al-O-Al sites in tetrahedral networks. The former contains one peak with isotropic chemical shift (δ iso ) = 30.9 ppm and quadrupolar coupling constant (C Q )…
The electronic structure of perovskite manganese oxides is investigated in terms of a Kondo lattice model with ferromagnetic Hund coupling and antiferromagnetic exchange between ${t}_{2g}$ spins using a finite temperature diagonalization technique. Results for the dynamic structure factor are consistent with recent ne…
Dimeric tetrathiafulvalene (TTF) derivatives may be useful for increasing the dimensionality in materials with conducting properties, since the stacks or slabs formed by the TTF moieties may be coupled together in a second or third direction through the bridging group. Here is reported the synthesis of a novel twin-π-…
Neutron diffraction patterns, collected at room temperature and, with in situ thermal treatment, from 981 to 1173 K, on a zirconia sample containing 3 wt% of sodium, show the presence and the stability of the cubic form of zirconia from 298 to 1073 K. The analysis has also demonstrated the presence of a significant am…
Abstract The adsorption of DL-alanine at pH 4, 6 and 8 by a soil allophane has been determined. Two sets of experiments were carried out: (1) in which the allophane had been kept in a moist state throughout; and (2) in which the mineral had previously been dried at 50°C. In both instances, the adsorption isotherms sho…
The Si L 2,3 core-loss edge can be used to probe the crystal chemistry around Si, providing information on the s- and d-like partial density of unoccupied states of the Si-O bonds. We present Si L 2,3 edges from 59 silicates, glasses, and amorphous materials acquired by parallel electron energy-loss spectroscopy (PEEL…
Experimental studies of the ferromagnetic resonance spectra of polycrystalline hexagonal ferrites of the system Co 2− x Zn x W in the frequency range 16–32 GHz are described. It is shown that interpretation of the experimental data requires the assumption of an anisotropic effective magnetomechanical ratio (or g -fact…
Different semiaromatic polyamides (SAPA) have been synthesized by step-growth polymerization of an aliphatic diamine, M (the 2-methyl 1,5-pentanediamine), and isophthalic acid, I, or terephthalic acid, T, or mixtures of these two diacids. The influence of the relative amount of randomly distributed MT units on the vis…