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The high‐temperature transition monoclinic tetragonal in the rare‐earth tantalates and niobates with the formula AB04 was investigated using a high‐temperature X‐ray diffractometer. The transition was reversible and proceeded by a gradual change in symmetry. The temperature of the first appearance of the tetragonal ph…
The direct and converse piezoelectric effects have been observed in the Achilles tendon of ox and horse, which consists of collagen fibers in which the collagen molecules are highly orientated and crystallized. The matrix of piezoelectric constant is concordant with that derived for and unidirectionally oriented syste…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTParticle to Particle Migration of Hydrogen Atoms on Platinum—Alumina Catalysts from Particle to Neighboring ParticlesS. KhoobiarCite this: J. Phys. Chem. 1964, 68, 2, 411–412Publication Date (Print):February 1, 1964Publication History Published online1 May 2002Published inis…
The stability of the shape of a moving planar liquid-solid interface during the unidirectional freezing of a dilute binary alloy is theoretically investigated by calculating the time dependence of the amplitude of a sinusoidal perturbation of infinitesimal amplitude introduced into the planar shape. The calculation is…
CONTENTS I. Oxidation in gas and liquid phases 13 II. Oxidation in the solid phase 14 III. Oxidation of polypropylene 15 IV. Critical antioxidant concentration 18 V. Initiation of oxidation by antioxidants 20 VI. Theory of synergism 21 VII. Free radicals as stabilisers 23 VIII. Borate stabilisers 25
Abstract Polymers of propylene having highly regular isotactic structure and low molecular weight (down to about 800) were prepared. The melting point, the X‐ray crystallinity, the solubility in some solvents, and the molecular weight of each polymer fraction have been determined. The melting point increases with the…
Vitreous silica compacted by pressure at room temperature expands at a very rapid rate when irradiated with soft x rays or in a reactor, about in the ratio of the ionization doses received. A dose \ensuremath{\sim}\textonehalf{} ${10}^{22}$ eV/${\mathrm{cm}}^{3}$ (i.e., ${10}^{8}$R) of absorbed ionization energy cause…
The paramagnetic resonance spectrum of single crystals of $\ensuremath{\alpha}\ensuremath{-}{\mathrm{Al}}_{2}{\mathrm{O}}_{3}$ containing chromium grown under conditions favoring the stabilization of ${\mathrm{Cr}}^{4+}$ has been observed. Data were taken at $X$ band at liquid-helium temperatures. A single absorption…
Energy transfer from ${\mathrm{Er}}^{3+}$ to ${\mathrm{Tm}}^{3+}$ and ${\mathrm{Ho}}^{3+}$ ions in crystals has been found to occur. Transfer proceeds from the $^{4}I_{\frac{13}{2}}$ state of ${\mathrm{Er}}^{3+}$ to the $^{3}H_{4}$ and $^{5}I_{7}$ emitted states of ${\mathrm{Tm}}^{3+}$ and ${\mathrm{Ho}}^{3+}$, respec…
These compounds are strongly magnetic. For the heavier rare earths, the gross magnetic moment appears to arise from opposed alignment of the rare earth and the cobalt atoms. If we assume the rare earths to have characteristic localized magnetic moments $\mathrm{Jg}$, the moments on the cobalt atoms are about 1.7 \ensu…
Results of Hartree-Fock calculations on the ions of ${\mathrm{Li}}^{\ensuremath{-}}$, ${\mathrm{B}}^{\ensuremath{-}}$, ${\mathrm{C}}^{\ensuremath{-}}$, ${\mathrm{N}}^{\ensuremath{-}}$, ${\mathrm{O}}^{\ensuremath{-}}$, ${\mathrm{F}}^{\ensuremath{-}}$, ${\mathrm{N}}^{\ensuremath{-}\ensuremath{-}}$, ${\mathrm{O}}^{\ensur…
Radiation damage has been studied by numerically integrating the equations of motion of a large set of atoms on a high-speed computer. In this paper the method is applied to a model of $\ensuremath{\alpha}$ iron. Low energy events have been extensively investigated. The primary knock-on atom is found to initiate an ex…
Expansion of kaolinite with potassium acetate and with hydrazine followed by deuteration, shifts the absorption frequency at 3695 cm(-1) to lower values, but does not aflect the intensity of the 3620-cm(-1) absorption band. The band at 3695 cm(-1) is correlated predominantly to inner-surface hydroxyls with the dipole…
Absolute infrared intensities have been measured for ν2 and ν3 of CS2 in the solid phase. Path lengths were measured by counting interference fringes as the solid is condensed onto a cold window. The index of refraction of the solid film is estimated from the intensity of the fringe pattern on different windows of kno…
The (triplet-state) TCNQ ion radical salts and also Würster's blue perchlorate exhibit deviations from the normal behavior of typical molecular solids. These systems are believed to contain triplet excitons which are restricted to essentially a unidirectional propagation. A simple phenomenological model is presented w…
Views Icon Views Article contents Figures & tables Video Audio Supplementary Data Peer Review Share Icon Share Twitter Facebook Reddit LinkedIn Tools Icon Tools Reprints and Permissions Cite Icon Cite Search Site Citation C. G. B. Garrett, F. R. Merritt; PMR SPECTRA OF Nd3+ IN COMPENSATED AND UNCOMPENSATED CaWO4. Appl…
The quantum yield of the potassium ferrioxalate actinometer at 365/6 mμ has been measured to be 1.26±0.03 relative to a calibrated thermopile. Comparisons of thermopiles were carried out at the Eppley Laboratory and at the National Bureau of Standards to ensure the flatness of thermopile response. Irradiations were ma…
The crystal structure of CaWO4 (scheelite) has been refined with single-crystal x-ray diffraction data. For the tetragonal cell a=5.243±0.002, c=11.376±0.003 Å. Oxygen coordinates 0.1504, 0.0085, and 0.2111 correspond to Ca–O distances 2.44 and 2.48 Å and W–O distances 1.78 Å.
The CaWO4 structure has been refined, starting with the parameters of Sillén and Nylander, using two zones of neutron diffraction data. The oxygen coordinates with the origin of the cell at the W atom (4̄) are x=0.2413 (σ=0.0005), y=0.1511 (σ=0.0006), z=0.0861 (σ=0.0001). The slightly distorted WO4 tetrahedron contain…
The Slater theory of the ferroelectric phase transition in K${\mathrm{H}}_{2}$P${\mathrm{O}}_{4}$ type crystals as modified by Takagi and extended by Senko is examined again in the light of recent measurements of parameters made on K${\mathrm{D}}_{2}$P${\mathrm{O}}_{4}$. Making full use of the measurements, and assign…