Materials Literature
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A method of comparing the kinetics of isothermal solid‐state reactions based on the classical equation for analysis of nucleation‐and‐growth processes is described. In this method, plots of In In (1‐α) vs In (time), where α is the fraction reacted, are used to distinguish reaction mechanisms. Even nonintegral slopes o…
Abstract A novel and general synthesis of δ‐lactones from glutaraldehyde is described. The dialdehyde is first reacted with an alkyl or substituted alkyl Grignard reagent to afford a δ‐hydroxyaldehyde in good yield. These aldehydes exist preferentially in the cyclic hemiacetal form (δ‐lactols). Oxidation of the latter…
The superconducting resistive transition of the layer compound Nb${\mathrm{Se}}_{2}$ has been observed for crystals a few layers thick. The ${T}_{c}$ decreases as the crystal thickness is reduced below six Nb${\mathrm{Se}}_{2}$ layers, and a ${T}_{c}$ of 3.8\ifmmode^\circ\else\textdegree\fi{}K is predicted for a singl…
The book is devoted to a systematic description of physical phenomena in ferroelectrics and antiferroelectrics. Serious attention is given to thermodynamic, dynamic and model theories of ferroelectricity, which are set forth in a form understandable to a wide range of readers. Results of experimental studies and their…
The directions of the easy magnetization in the ${\mathrm{Ho}}_{x}{\mathrm{Tb}}_{1\ensuremath{-}x}{\mathrm{Fe}}_{2}$ system have been determined by means of the M\"ossbauer effect in $^{57}\mathrm{Fe}$. If the direction of magnetization of the system is described by an ($x,T$) spin-orientation diagram, it is found tha…
Abstract Copolymers of ethylene with relatively small amount of nine species of α‐olefins, i.e. , propylene, butene‐1, pentene‐1, hexene‐1, octene‐1, dodecene‐1, octadecene‐1, 4‐methylpentene‐1, and 4.6‐dimethylheptene‐1 were prepared with the use of ZIEGLER‐NATTA catalyst and their melt properties, crystalline behavi…
The thermoluminescence spectrum and phosphorescence decays of Harshaw KCl samples gamma irradiated at room temperature have been studied up to 400 degrees C. For the six peaks found, the order of the kinetics of recombination, the pre-exponential factor and the activation energy have been obtained. It has been observe…
For pt. III see ibid, vol. 4, 2611 (1971). Electron-phonon interaction effects in tunnelling junctions are considered in the framework of the formalism proposed in Pt. I (see abstr. A52955 of 1971). This formalism is simplified and then used to study electron-phonon interaction in metal-insulator-metal junctions. The…
NiMnSb and CoMnSb alloys were studied using neutron diffraction, X-ray diffraction, and magnetometric techniques. The distribution of the constituent atoms over the four sublattices was found and at 77 °K the magnetic structure of the alloys was determined. In NiMnSb a magnetic moment of (3.85 ± 0.05) μB was found onl…
Measurements of the high-field transverse electrical and thermal conductivities ${\ensuremath{\sigma}}_{\mathrm{xx}}$ and ${\ensuremath{\kappa}}_{\mathrm{xx}}$ of a high-purity tungsten single crystal are presented for the temperature range 1.5-6 K. The magnetic field dependences of the conductivities conform excellen…
A differential parallel-plate capacitance dilatometer has been used to measure the linear thermal-expansion coefficients of free-standing samples of solid argon (1-35 K), krypton (1-45 K), and xenon (1-105 K). The present data for argon and krypton are systematically larger than existing x-ray lattice-parameter data a…
Transport properties of sputtered VO2 films are shown to be critically dependent on the defect structure of this material. Measured values of thermoelectric power and Hall mobility for films deposited under optimum conditions are comparable to those previously measured on single crystals.
Electroabsorption was measured on selenium single crystals as a function of temperature, polarization of light, and direction of the modulating electric field. Interpretation along the lines of Elliot's theory of indirect excitonic transitions yields the assignment of the conduction-band minimum to the point $Z=(0, 0,…
The results of augmented-plane-wave (APW) energy-band calculations for the $3d$ transition-series monoxides CaO, TiO, VO, MnO, FeO, CoO, and NiO are interpreted in terms of the electrical and optical data for these compounds. A detailed analysis of the effects of a crystalline field on the nonmagnetic $d$ bands in the…
The crystal structure of Gdz(MoO4)a has been investigated both at room temperature and at elevated temperatures below and above the ferroelectric-ferroelastic transition temperature (~ 160°C). Space group, unit-cell dimensions, and formula units per unit cell Pba2 (C8v), a= 103881 +00003, b= 104194+0.0004, c= 107007+0…
In this paper we report measurements of the effects of large static uniaxial stress along [001], [111], and [110] on the frequency of the $\stackrel{\ensuremath{\rightarrow}}{\mathrm{k}}\ensuremath{\approx}0$ optical phonons in Ge, GaAs, GaSb, InAs, and ZnSe using first-order Raman scattering. In the absence of stress…
Based on empirical evidence, it is suggested that the energy band structure in PbPo may be inverted from that in PbS, PbSe, and PbTe. This inversion would result in PbPo having an ${{L}_{6}}^{+}$ conduction-band edge and an ${{L}_{6}}^{\ensuremath{-}}$ valence-band edge, implying a negative value of the energy gap ${E…
We have observed a new conduction mechanism in granular metals at low temperatures and high electric fields $\mathcal{E}$ characterized by a field-dependent conductivity ${\ensuremath{\sigma}}_{0}\mathrm{exp}(\frac{\ensuremath{-}{\mathcal{E}}_{0}}{\mathcal{E}})$. A theory based on a simple model of field-induced elect…
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In the preparation of impregnated catalyst composed of alumina carrier and cobalt salt the mixture of alumina or alumina hydrate and cobalt salt is calcined at the temperature between 500°and 800°C. From the theoretical and practical viewpoints it is important to clarify the state of cobalt compounds in the prepared c…