Materials Literature
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Oxygen perovskites show remarkable diversity in chemical composition. Ferroelectric and ferrodistortive effects are observed extraordinarily often. The chemical bonds represent an intermediate state between ionic (heteropolar) and covalent (homopolar) bond formation. The electronegativities defined by Pauling serve he…
The acidic and basic solubilities of the potential thermal barrier oxide components CeO2, HfO2, and Y2O3 were measured as a function of solvent basicity for fused Na2SO4-30 mol% NaVO3 at 900 C and 1 atm O2. Y2O3 solubility was higher than that of CeO2 or HfO2. For comparison, the solubility of CeO2 was measured in pur…
In certain ferroelectric liquid crystals that contain the biphenylyl moiety, the spontaneous polarization undergoes a change in direction relative to the optical axis of the system as a function of temperature. Consequently, at a characteristic temperature for a particular derivative, the polarization vanishes. A mode…
Electron-spin-resonance (ESR) studies of pristine and heavily doped polyacenic materials prepared by pyrolytic treatment of phenolformaldehyde resin have been carried out. Five pyrolysis temperatures (${T}_{p}$) in the range 500--900 \ifmmode^\circ\else\textdegree\fi{}C were selected to check the magnetic properties o…
We have used electron-beam lithography to fabricate superconducting ``wire'' arrays in a variety of patterns ranging from periodic to random and including the intermediate quasicrystalline and incommensurate configurations. Sweeping an applied magnetic field while observing the critical temperature reveals which field…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTFormation of luminescent, bent iridium-thallium-iridium and iridium-lead-iridium chains through the binding of thallium(I) and lead(II) to the iridium metallomacrocycle Ir2(CO)2Cl2[.mu.-(Ph2PCH2)2AsPh]2Alan L. Balch, Jeffrey K. Nagle, Marilyn M. Olmstead, and Philip E. Reedy…
The freezing transition of ‘‘soft spheres,’’ which interact via inverse-power potentials v(r)∼r−n, is systematically investigated for various values of the steepness n, using density functional theory. Two ‘‘second-order’’ theories are considered, which require as only input the static pair structure of the homogeneou…
The hydrostatic pressure dependences of the static dielectric constants and phase transitions of the mixed perovskite crystals KTa0.68Nb0.32O3 (KTN) and K0.5Na0.5NbO3 and of LiTaO3 and LiNbO3 were investigated. For the mixed perovskites the pressure responses are qualitatively similar to those observed earlier for pur…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTPolyhedral clusters in solids. Electronic structure of pentlanditeJeremy K. Burdett and Gordon J. MillerCite this: J. Am. Chem. Soc. 1987, 109, 13, 4081–4091Publication Date (Print):June 1, 1987Publication History Published online1 May 2002Published inissue 1 June 1987https:…
The freezing of 1:1 mixtures of hard spheres is studied using density functional theory. Three different stable solid phases are found: a disordered (phase separated) fcc structure and ordered CsCl and NaCl structures. The relative stability of these phases is predicted as a function of the ratio of the diameters of t…
A simple electron-phonon coupling model is constructed for the layered-metal oxides. The predictions of the model are the tetragonal-to-orthorhombic instability and separately from it, the bond dimerization within the layers. High T c in those materials is associated with the soft shear phonon branch in their tetragon…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTNMR properties of the complexes trans-[M(.eta.2-H2)(H)(PEt2CH2CH2PEt2)2]+ (M = Fe, Ru, Os). Intramolecular exchange of atoms between .eta.2-dihydrogen and hydride ligandsMaria Bautista, Kelly A. Earl, Robert H. Morris, and Andrea SellaCite this: J. Am. Chem. Soc. 1987, 109,…
A variety of inorganic solids have been prepared in recent years by employing a wide range of conditions such as irradiation by laser or electron beams, use of high pressures, high vacuum, or hydrothermal conditions, rapid quenching of melts, melting in a watercooled copper container using rf power (skull melting) or…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTTetratellurafulvalene(TTeF)Richard D. McCullough, Gaik B. Kok, Knud A. Lerstrup, and Dwaine O. CowanCite this: J. Am. Chem. Soc. 1987, 109, 13, 4115–4116Publication Date (Print):June 1, 1987Publication History Published online1 May 2002Published inissue 1 June 1987https://pu…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTStructure of the hydrated electronH. F. Hameka, G. W. Robinson, and C. J. MarsdenCite this: J. Phys. Chem. 1987, 91, 12, 3150–3157Publication Date (Print):June 1, 1987Publication History Published online1 May 2002Published inissue 1 June 1987https://pubs.acs.org/doi/10.1021/…
Abstract The structure and synthesis of some poly(vinylsaccharide)s is described. Five different monomers, N ‐saccharide‐substituted acryl‐and methacrylamides, were prepared and polymerized to high molecular weight products using different initiator systems. The influence of the chemical structure of the saccharide mo…
High-resolution neutron and X-ray diffraction data for vitamin B~2 coenzyme have been obtained with the objective of elucidating the water organization in this crystalline system. Here, details of the data collection and refinement of the individual models are described. Neutron data: Mr = 1939 (assuming exchange of 1…
The fracture initiation and arrest stress intensity factors were determined for a SiC‐whisker‐reinforced AI 2 O 3 matrix composite. A chevron‐notched, three‐point‐bend specimen was used to genera e the load/displacement curve, which exhibited repeated crack initiation, followed by crack arrest behavior. Corresponding…
Abstract Aromatic polyesters and polyamides with disc‐like mesogens in the main chain were prepared from tetra‐substituted hydroquinones and derivatives of 1,4‐phenylenediamine. Depending on the atomatic acids (terephthalic acid, 2,5‐dialkoxyterephthalic acid) used in the condensation reaction, the repeating units of…
A procedure was developed to purify large quantities of PII protein from an Escherichia coli strain which contains a multicopy plasmid harboring the structural gene of PII (the glnB gene). Ultraviolet spectra of uridylylated and unuridylylated PII were obtained using the purified PII and empirical formulas to calculat…