El yeso en la prefabricación
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Magnetic Properties of Manganese Telluride Single Crystals
The susceptibility and torque measurements of antiferromagnetic manganese telluride are made on the samples of single crystals. The spin orientation and structure are studied and discussed for the observed results of the field dependence and field cooling measurements. Some simple calculations are carried out, and som…
Mortero para reparaciones rápidas en suelos de talleres y escaleras
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Desarrollo tecnológico de la industria del cemento
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Magnetic Structures in the MnSb-CrSb System
A magnetic and neutron diffraction investigation has been made on MnSb, CrSb, and their solid solutions, which crystallize in the hexagonal NiAs-type structure. MnSb is ferromagnetic and CrSb antiferromagnetic. As CrSb is substituted into MnSb, a canted spin structure is formed, the spins lying within ferromagnetic (0…
Optical Properties of Powders. Part I. Optical Absorption Coefficients and the Absolute Value of the Diffuse Reflectance. Part II. Properties of Luminescent Powders
The optical properties of powders are determined for the case of particles, large compared with the wave-length of light. The solution for the diffusion of light in a quasi-infinitely thick powder is applied to relate certain measurements obtained on powders with the corresponding properties of the bulk material. In P…
Direct Transformation of Hexagonal Boron Nitride to Denser Forms
Hexagonal, graphitelike boron nitride may be changed directly into the zincblende cubic form reported earlier or into a new wurtzite form by the application of static high pressures. No catalyst appears to be necessary. At high temperatures, between about 2500° and 4000°K, the zincblende form is favored; at lower temp…
Crystal Structures at High Pressures of Metallic Modifications of Silicon and Germanium
Studies of germanium and silicon by x-ray diffraction reveal that their crystal structure changes at high pressures from the semiconducting diamond-type structure to the metallic white tin structure, in analogy to the known "gray" to "white" transition in tin itself.
The magnetization of face-centred cubic and body-centred cubic iron + nickel alloys
Abstract Magnetizations of single phase binary iron + nickel alloys have been measured and Bohr magneton numbers p estimated for body-centred cubic alloys with 0 to 32.3 at. % of nickel and for face-centred cubic alloys with 31 to 80 %. Initially p increases at the rate 1.1 ±0.1 μB per nickel atom in iron-rich b.c.c.…
Thresholds Observed in theC12(α,n)O15,Si28(α,n)S31,S32(α,n)Ar35,S34(α,n)Ar37, andCl35(p,n)Ar35Reactions
The following thresholds have been measured in the ($\ensuremath{\alpha},n$) reaction: ${\mathrm{C}}^{12}$ 11.341\ifmmode\pm\else\textpm\fi{}0.015; ${\mathrm{Si}}^{28}$ 9.30\ifmmode\pm\else\textpm\fi{}0.05, 10.55\ifmmode\pm\else\textpm\fi{}0.05, 11.83\ifmmode\pm\else\textpm\fi{}0.05, 12.78\ifmmode\pm\else\textpm\fi{}0…
Complex Dielectric Constant of KH2PO4at 9.2 Gc/sec
The temperature dependence of the dielectric constant and loss tangent in potassium dihydrogen phosphate along and normal to the optic axis has been measured by a cavity perturbation method at 9.2 Gc/sec. The dielectric constants agree with earlier low-frequency measurements. The parallel dielectric constant exhibits…
Reflection and Diffraction of Slow Electrons from Single Crystals of Tungsten
Measurements have been made of the elastic reflection coefficient and total secondary electron coefficient for electrons with energies from 1-206 eV incident normally on single crystals of tungsten (112), (100), and (110). The apparatus permitted visual observation of the full diffraction pattern in the same energy ra…
Investigation ofTa2C,Nb2C, andV2C for Superconductivity
Previous investigators have reported that ${\mathrm{Ta}}_{2}$C and ${\mathrm{Nb}}_{2}$C became superconducting at 3.26 and 9.18\ifmmode^\circ\else\textdegree\fi{}K, respectively. In this work, no superconducting transition was found in pure compounds of ${\mathrm{Ta}}_{2}$C and ${\mathrm{Nb}}_{2}$C for measurements do…
Dielectric Constant ofCr2O3Crystals
The dielectric constants of ${\mathrm{Cr}}_{2}$${\mathrm{O}}_{3}$ were measured at 25.5\ifmmode^\circ\else\textdegree\fi{}C by a two-terminal substitution method on specimens cut from single crystal. The average dielectric constants thus obtained are: at 1 kc/sec parallel $a$ axis 13.3, parallel $c$ axis 11.9; at 2 Mc…
Far Infrared Antiferromagnetic Resonance in MnO and NiO
The uniaxial dipolar anisotropy in antiferromagnetic MnO and NiO aligns the two opposing sublattice moments in an easy (111) plane. The two normal modes for small oscillations of the sublattice magnetizations about a preferred direction within this plane are both nondegenerate and linearly polarized. The high-frequenc…
Measurement of Equilibrium Concentrations of Vacancies in Copper
The net added fraction of thermally-generated atomic sites, $\frac{\ensuremath{\Delta}N}{N}$, has been measured, during equilibrium heating to near the melting point, in a coarse-grained copper bar of 99.999% purity. The linear thermal expansion, $\frac{\ensuremath{\Delta}L}{L}$, and the x-ray lattice expansion, $\fra…
Temperature Dependence of Dielectric Constants of Cubic Ionic Compounds
The temperature and pressure dependence of the dielectric constant of a number of cubic halides and oxides with a broad range of dielectric constants have been determined. For low-$\ensuremath{\epsilon}$ compounds the dielectric constant increases with increasing temperature, whereas for high-$\ensuremath{\epsilon}$ c…
Optical Properties of Semiconductors
Reflectance data are presented for Si, Ge, GaP, GaAs, InAs, and InSb in the range of photon energies between 1.5 and 25 eV. The real and imaginary parts of the dielectric constant and the function describing the energy loss of fast electrons traversing the materials are deduced from the Kramers-Kronig relations. The r…
Polymer Structure: Cross-Linking of a Polybenzimidazole
The torsional braid technique was used to monitor the changes in rigidity and damping characteristics of a polybenzimidazole as it changes from a thermoplastic polymer to a thermoset resin at about 450 degrees C. In an intermediate process the thermoplastic backbone of the polymer becomes flexible.
Der Einfluß mechanischer Zwillingsbildung auf die Entstehung der Walztexturen kubisch Hlächenzentrierter Metalle
Article Der Einfluß mechanischer Zwillingsbildung auf die Entstehung der Walztexturen kubisch Hlächenzentrierter Metalle was published on February 1, 1963 in the journal International Journal of Materials Research (volume 54, issue 2).