Materials Literature
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The superlattice and domain structures exhibited by the ordered compound V6C5 are disrupted by electron microscope beam bombardment. The effect is attributed to the disordering of the carbon sublattice that results from displacement of the carbon atoms by the impinging electrons. Studies have been made of the disorder…
Abstract An x‐ray study of poly( N ‐butyl isocyanate) (PBIC) was undertaken with the aim of providing the structural information required for the calculation of its ultraviolet absorption spectrum. Well defined diffraction patterns are obtained from powder samples and oriented films of the polymer cast from cyclohexan…
The conditions under which a given form of any of the three distinct polymorphic crystalline phases of isotactic polypropylene can be obtained have been investigated. The relationship between crystallization conditions and the formation of a given crystalline phase is discussed. Evidence is cited in support of the hyp…
The consequences of a simple type of exchange interaction between charge carriers in a broad energy band and localized magnetic moments will be discussed for a ferromagnetic semiconductor. The interaction causes (1) a splitting of the energy band into two bands for the different spin directions, (2) spin disorder scat…
A general theory is developed to account for the mobility of a dislocation which is sessile in its low-energy form. It is shown that three distinct mechanisms for movement are possible, each controlling the mobility over a different stress range. A specific core model is used to derive an expression for the mobility o…
The antiferromagnetic perovskites have a simple cubic-magnetic structure with nearest-neighbor exchange interactions only. The perfect-crystal Green functions can be easily expressed in terms of tabulated integrals, so that they are particularly suitable for making quantitative comparison between theory and experiment…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTCellulose Xanthic Acid. I. Studies of Model SystemsJohn Dyer and Lyle H. PhiferCite this: Macromolecules 1969, 2, 2, 111–117Publication Date (Print):March 1, 1969Publication History Published online1 May 2002Published inissue 1 March 1969https://pubs.acs.org/doi/10.1021/ma60…
Abstract Monocrystals of calcium tartrate tetrahydrate, neodymium‐doped calcium tartrate tetrahydrate, and cuprous chloride have been grown by controlled diffusion in silica gel using both metathetical and decomplexation reactions. Conditions for the optimum growth of the crystals are given and it is shown how the p H…
I. Single crystals of Alnico V and Alnico VIII alloys with 35, 40, and 42 wt.% Co and 5, 7, and 8 wt.% Ti, respectively, were investigated by x-ray analysis and electron microscopy of thin foils. It was found: (1) In Alnico V, alloy decomposition begins with the formation of randomly arranged equiaxial spherical zones…
The crystal structure of gratonite has been redetermined with the use of three-dimensional intensity data. The intensities were obtained by counter and photographic technique. Three chemical units of Pb 9 As 4 S 15 are contained in the unit cell of the symmetry C 3 v 5 – R 3 m with a hex = 17.758 ± 0.014 Å, c hex = 7.…
The numerical method of deconvolution described in part I is applied to a study of a broadening factor of the diffractometer: the receiving slit. By considering this factor the validity of this direct method of deconvolution, which can also be applied to analytical profiles and to experimental profiles, is verified. T…
It is proposed that silicate glasses be classified in terms of substructures uniquely identified with primary crystallization phases. All glasses having compositions within the ranges or areas covered by a given primary crystallization phase field should constitute a separate glass type or class. This classification i…
. Above 1405 °C dissociation is complete for all compositions and the phase relations are represented by the Ru-Ir system. At 1500 °C solid solution of Ru and Ir occurs with the addition of up to 45 mole percent Ir and up to 44 mole percent Ru, respectively.
Pure iron manganite FeMn2O4 was prepared at 1250°C and quenched. It crystallizes in the b.c. tetragonal system D4h19. Neutron diffraction measurements above the Curie temperature (120°C) show that the inversion parameter is 0.91 (nearly inverse spinel). The spontaneous magnetization at 4.2°K measured in high static an…
A new method of correction of X-ray powder diffraction line profiles by deconvolution is being developed. The convolution equation, representing the phenomenon of deformation of a true diffraction line profile, is approached with the help of a quadrature formula by a system of linear equations. The bad conditioning of…
Grain-oriented silicon iron with high permeability is prepared using aluminum-nitride needles to restrain normal grain growth. The improvements in hysteresis loss of specimens with a permeability of 1920 are about 0.120 W/kg at 15 kG and 0.160 W/kg at 17 kG as compared to the commerical product with a permeability of…
The possible existence of antiferromagnetism in Ti2O3 has important theoretical implications associated with the explanation of the metal-to-semiconductor transition in this material. A previous neutron-diffraction study, using unpolarized neutrons, indicated that Ti2O3 was antiferromagnetic with the α-Fe2O3 structure…
Abstract Oriented X‐ray spacings for vermiculite and montmorillonite were obtained as the sample temperature was changed at a constant rate. Temperatures at which an abrupt change in (001) spacing took place indicated the relative ease of expansion or contraction for a series of interlayer ions. From such temperatures…
The stress required to operate dislocation sources within a grain, at a grain boundary, and at surfaces is found to be larger than the intrinsic stresses observed in polycrystalline films. It is therefore unlikely that a dislocation flow mechanism can relieve stresses in films. Grain boundary sliding and diffusional c…
SUMMARY– We studied oxidation of a freeze‐dried model system consisting of methyl linoleate and gelatin by incubating the model system in air at 50°C for up to 10 days in the dry state or at controlled relative humidities. Incubation for 5‐10 days caused a drop in the viscosity of gelatin solutions, an increase in the…