Materials Literature
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A previous paper proposed a model for polymer crystallization under stress [1]. This paper suggested that there could be distinctive crystals which formed under stress at unusually high temperatures to act later as nuclei for the bulk of the crystals. The present paper details definitive evidence for these nucleating…
SUMMARY Cemented layers in the shallow lagoonal, intertidal, and supratidal sediments surrounding the Qatar Peninsula, Persian Gulf, contain high‐magnesian calcite and aragonite cements. The magnesian calcite appears to occur both as a primary precipitate and as a replacement of aragonite. These cements are believed t…
Two basic assumptions are usually made by crystallographers in the evaluation of X-ray or neutron structure factors. The first is the validity of the harmonic approximation in deriving the Debye–Waller factors which account for the effect of lattice vibrations in reducing the intensities of the Bragg reflexions. The s…
A unified treatment is given of various properties of ferroelectric crystals in their non-polar phases, typified by BaTiO3, KH2PO4 and NaNO2. Certain relations are established between measurable dielectric and scattering properties. Critical scattering is discussed in terms of lattice dynamics.
Anhydrous lithium perchlorate has been examined in the crystalline and molten state by infrared and Raman spectroscopy. In the crystalline phase all degenerate modes are split but the Raman and infrared spectra are essentially identical in the internal frequency region. In the molten state the spectra are more simple…
A theory based on flow across a selected control volume is devel oped to predict the Hugoniot of a shock moving along the longitudinal direction of a unidirectional fiber reinforced composite. From this theory the Hugoniot of a composite may be calculated from the equa tions of state of its constituents. The shear for…
The strength and fracture behaviour of ceramics are considered with particular reference to oxides. Ceramics fracture in a brittle manner and the strength of most materials is about two orders of magnitude less than the theoretical strength. Strength is discussed conveniently in terms of a modified Griffith equation a…
A neutron diffraction study has been made of powdered samples of CrAs and Mn-substituted CrAs, namely, Cr0.7Mn0.3As, Cr0.4Mn0.6As, and Cr0.3Mn0.7As. Although CrAs shows a kink in susceptibility at 796°K, the anomaly was found to be due to a crystallographic transformation, from MnP-type structure (low-temperature side…
Previously, most basic magnetic properties of the hexagonal intermetallic compounds involving the rare-earth (RE) and 3-d transition elements were reported in the literature. In addition, some of these compounds were investigated by various workers for permanent magnet properties by grinding ingots of the compounds in…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTCarbon as Adsorbent and CatalystRobert W. CoughlinCite this: Ind. Eng. Chem. Prod. Res. Dev. 1969, 8, 1, 12–23Publication Date (Print):March 1, 1969Publication History Published online1 May 2002Published inissue 1 March 1969https://pubs.acs.org/doi/10.1021/i360029a003https:/…
Abstract Polymers of poly( N ‐acyl and N ‐aroyl aziridines) were studied by x‐ray diffraction. All the crystalline polymers studied have a triclinic unit cell with two monomer units per unit cell. The a and c (fiber direction) parameters (4.9 and 6.5 A, respectively) are essentially the same for all the cells. The b p…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTPhase transformations and electrical properties of bismuth sesquioxideC. N. Ramachandra Rao, G. V. Subba Rao, and S. RamdasCite this: J. Phys. Chem. 1969, 73, 3, 672–675Publication Date (Print):March 1, 1969Publication History Published online1 May 2002Published inissue 1 Ma…
Abstract The effects of ultrasonic vibrations on heat transfer to water and methanol by natural convection and by boiling were measured at three ultrasonic energy levels with frequency ranging from 20.6 to 306 kcycles/sec., using electrically heated platinum wires of diameters 0.007 and 0.010 in. Up to an eight‐fold i…
Measurements of the field dependence of the critical temperature (Tcrit) for the first-order antiferromagnetic-ferromagnetic transition in FeRh established that the total entropy change (ΔST) at Tcrit is much larger than the change in lattice entropy (ΔSL). Doping experiments (Pd, Pt, or Ir) showed that ΔST−ΔSL=ΔS var…
Cobaltic acid, HCoO2, and deuterated cobaltic acid, DCoO2, have been prepared and studied by x-ray and neutron-diffraction techniques, and by infrared spectroscopy and cold-neutron scattering. The materials crystallize in apparent space group D3d5–R<3¯m of the trigonal system with three molecules in a hexagonal…
Abstract Bray and Morgan soil extracting solutions were modified to increase their usefulness in testing acidic soils of different parent materials and ranges of fertility. The Morgan extractant was changed by substituting NH 4 for Na. For equilibration type extractions, NH 4 removes more K from clay soils than does N…
We have measured magnetization isotherms for single crystals of monoclinic Cu(NO3)2·2.5H2O between 1.2° and 4.2°K by a ballistic method. Fields up to 43 kOe were applied along the b axis, i.e., the long axis of the needlelike specimens. The character of the M vs H curves changes rapidly in this temperature interval. T…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTCoordination compounds with delocalized ground states. Transition metal derivatives of dithiodiketones and ethylene-1,2-dithiolates (metal dithienes)Gerhard N. SchrauzerCite this: Acc. Chem. Res. 1969, 2, 3, 72–80Publication Date (Print):March 1, 1969Publication History Publ…
Saturation magnetizations in the binary Fe–Co system were redetermined since an earlier investigation (P. Weiss and R. Forrer, Ann. Phys. 12, 1929) was made prior to the discovery of a CsCl-type ordered structure that has a wide solubility range. The alloys were quenched from 850°C at various rates in an attempt to su…
Abstract Infraref internal reflection spectroscopy has been used to study the adsorption of certain plasma proteins on a variety of hydrophobic polymer surfaces. The behavior of the systems studied was almost identical. Under Static conditions the proteins appear to be rapidly adsorbed as monomolecular layers from sol…