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It has been tried to classify newly discovered ferroelectrics as well as old ones according to their Curie-Weiss constants. Results have suggested that the displacive type ferroelectrics are not necessarily oxide crystals, and have also shown that small Curie-Weiss constants are not very rare in new ferroelectrics. Cl…
Pressure sintering (or hot‐pressing) of pure alumina and magnesia in graphite dies and in ceramic dies over the range 1100° to 1700°C and 4000 to 10,000 psi has been shown to be very useful in fabricating these materials with controlled microstructures (e.g., very high relative density and fine grain size or controlle…
The transmission and reflection spectra of cuprous oxide have been measured from 2 to 25 μ. The transmission studies included Cu2O18. The isotope shifts help to establish that all the observed infrared bands are due to lattice vibrations and not to defect mechanisms as some authors have suggested. The reflectivity can…
Triplet energy migration and triplet-triplet annihilation leading to fluorescence radiation are discussed. The molecular crystals considered are arthracene and naphthalene. Conclusions concerning the mechanism of the triplettriplet annihilation, the recombination of the ion pair, and the rate- determining step in the…
Abstract Aromatic polyimides were prepared in two steps. Pyromellitic dianhy dride was added to a solution of an aromatic diamine in a highly polar solvent, such as dimethylformamide, dimethylacetamide, dimethyl sulfoxide, or N ‐methyl‐2‐pyrrolidone, until a high molecular weight polypyromellitamic acid was obtained.…
A calculation is presented of the generation of microwave elastic waves by the uniform precession resonance in ferromagnets. The excitation of the thickness shear modes in a normally magnetized ferromagnetic disk is treated. For uniform precession the elastic modes are driven only on the surfaces of the disk. The effe…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTAcid Retardation. Simple Physical Method for Separation of Strong Acids from Their SaltsM. J. Hatch and J. A. DillonCite this: Ind. Eng. Chem. Process Des. Dev. 1963, 2, 4, 253–263Publication Date (Print):October 1, 1963Publication History Published online1 May 2002Published…
An improved counterbalanced sphere viscometer was used to determine the viscosity of pure molten GeO2 at temperatures from 1470° to 1720°C. This data agrees with the Kurkjian and Douglas data obtained below 1500°C. Activation energy and entropy calculations suggest a gradual thermal breakdown of molten GeO2 compared t…
The annealing or volume variation with time of both silica and boron oxide glasses densified in the rigid state was studied. Appreciable annealing of silica glass was observed at temperatures as low as 200°C and of boron oxide glass at even room temperature. This anomalous volume flow depended on temperature, time, an…
ADVERTISEMENT RETURN TO ISSUEPREVArticleRecent Advances in the Chemistry of Pyrrole.Evan Baltazzi and Lewis I. KrimenCite this: Chem. Rev. 1963, 63, 5, 511–556Publication Date (Print):October 1, 1963Publication History Published online1 May 2002Published inissue 1 October 1963https://pubs.acs.org/doi/10.1021/cr60225a0…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTTHE CRYSTAL STRUCTURES OF BARIUM CHLORIDE, BARIUM BROMIDE, AND BARIUM IODIDEElizabeth B. Brackett, Thomas E. Brackett, and Ronald L. SassCite this: J. Phys. Chem. 1963, 67, 10, 2132–2135Publication Date (Print):October 1, 1963Publication History Published online1 May 2002Pub…
Densification of SiO 2 , GeO 2 , and B 2 O 3 glasses in the rigid state was studied at pressures up to 80 kb and at temperatures up to 600°C in different pressure‐transmitting media. The infrared, ultraviolet, and nuclear magnetic resonance absorptions of the compressed glasses were examined. Densification increased w…
A systematic derivation of the energy-flux operator for a three-dimensional lattice is given. The treatment is based on the general expressions for the energy flux which are valid for all phases of matter; a short derivation of these expressions, making no restrictions to two-body forces, is presented. The average ene…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTINFLUENCE OF CONSTITUTION ON ADHESIONW. A. ZismanCite this: Ind. Eng. Chem. 1963, 55, 10, 18–38Publication Date (Print):October 1, 1963Publication History Published online1 May 2002Published inissue 1 October 1963https://pubs.acs.org/doi/10.1021/ie50646a003https://doi.org/10…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTTHE IMPORTANCE OF ACTIVE SURFACE AREA IN THE CARBON-OXYGEN REACTION1,2N. R. Laine, F. J. Vastola, and P. L. Walker Jr.Cite this: J. Phys. Chem. 1963, 67, 10, 2030–2034Publication Date (Print):October 1, 1963Publication History Published online1 May 2002Published inissue 1 Oc…
The theory of the physical properties of an anharmonic crystal is discussed by using the thermodynamic Green's functions for the phonons. A perturbation procedure is developed to obtain the Green's functions and it is shown that for some purposes a quasi-harmonic approximation is useful, in which the frequencies of th…
One of the important properties of silicic acid is its tendency of polymerization. Therefore, its solution, when dilute, is always colloidal in property, and when of sufficient concentration, sets into a gel. There are many factors which influence the rate of polymerization of silicic acid, but the most important and…
Investigations of electron spin resonance (ESR) spectra of ${\mathrm{Yb}}^{3+}$ and ${\mathrm{Dy}}^{3+}$ in the cubic crystal field of calcium oxide show $g$ factors which are smaller than the calculated $g$ factors. It is shown that covalent bonding through the effect of the orbital reduction factor can explain these…
Reinvestigation of the region of the argon $K$ absorption edge has revealed a new resonance absorption structure followed by a new continuum. These new features may be interpreted as arising from double-electron-excitation processes involving an $M$ electron as well as the $K$ electron. The first new resonance line li…
Features of the optical absorption spectra of point defects in solids that are analogous to those of the Mossbauer spectra in solids are considered, and the observation of the corresponding zero-phonon lines associated with some of the F-aggregate color-center bands in LiF, NaF, NaCl, KCl, and KBr are reported. (C.E.S…