A method of determining the stress-strain relation of materials when stresses are applied for times of the order of 20 microseconds is described. The apparatus employed was a modification of the Hopkinson pressure bar, and detonators were used to produce large transient stresses. Thin specimens of rubbers, plastics an…

Laser-Plasma Interactions and DiagnosticsNuclear Physics and ApplicationsHigh-Velocity Impact and Material Behavior

The Dielectric Properties of Barium Titanate at Low Temperatures

R. F. Blunt、W. F. Love1949-10-15Physical Review

The complex dielectric constatn of ceramic barium titanate has been measured as a function of temperature from 300\ifmmode^\circ\else\textdegree\fi{}K down to 2.8\ifmmode^\circ\else\textdegree\fi{}K. The large value of the slope of the real part of the dielectric constant, ${K}^{\ensuremath{'}}$, versus temperature cu…

Ferroelectric and Piezoelectric MaterialsMicrowave Dielectric Ceramics SynthesisDielectric properties of ceramics

Domain Structures and Phase Transitions in Barium Titanate

P. W. Forsbergh1949-10-15Physical Review

The arrangements of domains that arise in single crystals of barium titanate in the ferroelectric tetragonal phase have been studied in detail. The domains are the results of tetragonal (101) twinning, and appear by the formation of wedge-shaped laminar domains between two converging (101) twin planes. The distance of…

Solid-state spectroscopy and crystallographyMaterial Science and ThermodynamicsOptical and Acousto-Optic Technologies

Detection of Antiferromagnetism by Neutron Diffraction

C. G. Shull、J. S. Smart1949-10-15OpenAlex

T necessary conditions for the existence of ferromagnetism are: (1) the atoms must have a net magnetic moment due to an unfilled electron shell, and (2) the exchange integral / relating to the exchange of electrons between neighboring atoms must be positive. This last condition is required in order that spin states of…

X-ray Diffraction in CrystallographyNuclear Physics and Applications

The Electric and Optical Behavior of BaTiO3Single-Domain Crystals

Walter J. Merz1949-10-15OpenAlex

The dielectric constants, the spontaneous polarization, and the optical properties of BaTi${\mathrm{O}}_{3}$ single-domain crystals have been measured as a function of temperature. It is shown that the deformation of the crystal in the tetragonal state is proportional to the square of the spontaneous polarization, in…

Glass properties and applicationsPhotorefractive and Nonlinear OpticsFerroelectric and Piezoelectric Materials

Transient Nutations in Nuclear Magnetic Resonance

H. C. Torrey1949-10-15OpenAlex

Transient nutations of the resultant nuclear magnetic moment vector are set up by applying radiofrequency power in the form of pulses in the neighborhood of resonance ($\ensuremath{\omega}=\ensuremath{\gamma}{H}_{0}$). The nutations have an initial amplitude depending on the state of magnetization at the start of a pu…

Electron Spin Resonance StudiesAdvanced NMR Techniques and ApplicationsSolid-state spectroscopy and crystallography

Crystal Statistics. II. Partition Function Evaluated by Spinor Analysis

Bruria Kaufman1949-10-15OpenAlex

The partition function for a two-dimensional binary lattice is evaluated in terms of the eigenvalues of the ${2}^{n}$-dimensional matrix V characteristic for the lattice. Use is made of the properties of the ${2}^{n}$-dimensional "spin"-representation of the group of rotations in $2n$-dimensions. In consequence of the…

X-ray Diffraction in Crystallography

Interstitial Atomic Diffusion Coefficients

C. A. Wert、Clarence Zener1949-10-15OpenAlex

An attempt is made to interpret the temperature independent factor ${D}_{0}$ of the previously determined diffusion coefficients of interstitial solute atoms in metals. The primary uncertainty in the value of ${D}_{0}$ given by the standard reaction rate theory resides in an entropy factor $\mathrm{exp}(\frac{\ensurem…

Nuclear Materials and PropertiesNuclear reactor physics and engineeringIntermetallics and Advanced Alloy Properties

The thermal degradation of polyvinyl compounds. I. A new type of molecular still

N. Grassië、H. W. Melville1949-10-07Proceedings of the Royal Society of London A Mathematical and Physical Sciences

Abstract A survey of depolymerization reactions has been made and the importance of the degradation emphasized in addition polymerization especially at high temperatures. In order to follow the course of the thermal degradation it is necessary to remove rapidly and measure the amount of monomer produced. In addition i…

Polymer Science and PVCbiodegradable polymer synthesis and propertiesAdvanced Polymer Synthesis and Characterization

The Ultraviolet Absorption and Luminescence of Decaborane

George C. Pimentel、Kenneth S. Pitzer1949-10-01The Journal of Chemical Physics

The ultraviolet absorption spectrum of decaborane in cyclohexane shows a broad absorption with a maximum molecular extinction coefficient of 3200±100A at wave-length 2720±50A. The luminescence of decaborane dissolved in a glass at 77°K shows a continuous fluorescence extending from 3630±50A to about 6000A with a broad…

Machine Learning in Materials ScienceBoron Compounds in ChemistryLuminescence and Fluorescent Materials