Materials Literature
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Pitting potentials have been measured potentiodynamically for Type 304 stainless steel in neutral or mildly acidic solutions containing 0.25M NaCl and various concentrations of sulfur species from 0 to 2 molar. Additions of 0.01 to 0.02M Na2S2O3 lowered the pitting potential by more than 300 mV, while additions of mor…
Pressure-induced phase transitions have been found in ${\mathrm{Cu}}_{2}$O and ${\mathrm{Ag}}_{2}$O by high-pressure x-ray diffraction technique at room temperature. ${\mathrm{Cu}}_{2}$O transforms from the cuprite to a hexagonal structure at a pressure of 10 GPa. This hexagonal form changes in the pressure range from…
The temperature dependence of the lattice constant in Na0.5Bi0.5TiO3 single crystal was studied by means of X-ray diffraction. Two structural phase transitions were found in the temperature range 293-920 K: the cubic-to-tetragonal at 793 ± 5 K and the tetragonal-to-rhombohedral at 533 ± 5 K. The dielectric permittivit…
Impurity doping effects on the properties of lead zirconate-titanate ceramics have been investigated from the internal bias field viewpoint. The internal bias field is strengthened by doping with single or multiple acceptors, but is weakened by single or multiple donors. Equimolar mixed acceptor and donor dopants have…
In this paper we discuss the quantum efficiency of the metastable4F_{3/2}state in Nd:YAG. We show that the vibronic interaction disrupts the equality between absorption and emission cross section ("reciprocity") upon which spectroscopic quantum efficiency measurements are based. Even if the electron-lattice coupling i…
Particles which undergo a stress‐induced martensitic transformation are known to toughen certain brittle materials. The enhanced toughness can be considered to originate from the residual strain fields which develop following transformation and tend to limit the crack opening. The increased toughness can estimated fro…
At -30 degrees C the ferroelectric dicalcium strontium propionate (DSP), is tetragonal with space group P4 1 (C 4 2 ) or P4 3 (C 4 4 ), with a=12.452(2) AA, c=17.217(4) AA, Z=4. There are six independent propionate groups in the structure, two of which have statistical disorder (static or dynamic) of their methyl carb…
Estimates were obtained of the intrinsic optical losses in glassy As 2 S 3 and As 2 Se 3 in the high-transparency range. It was found that minimum losses of 0.5 dB/km could be reached in the wavelength range 5–6 μ .
The properties of magnetic insulators containing orbitally degenerate transition metal ions (Jahn-Teller ions) are discussed. The Jahn-Teller effect in these insulators causes structural phase transitions, lowers the lattice symmetry, and gives rise to an orbital ordering. Various interactions responsible for these ef…
The microstructure of ortical thin films is strongly columnar with a large internal surface area and void volume. This structure has great influence on the optical and mechanical properties of the films and is responsible for many of the difficulties experienced with the fabrication and subsequent performance of optic…
The detailed proof of the 437-residue amino acid sequence (Mr 48,969) of porcine heart citrate synthase (EC 4.13.7) is described. The S-carboxymethylated protein has been cleaved at methionine (cyanogen bromide) and arginine (trypsin digest of citraconylated enzyme) residues to yield 14 and 17 major peptides, respecti…
Molecular-dynamics calculations have been used to investigate the nature of critical fluctuations in the paraelectric phase of NaN${\mathrm{O}}_{2}$. Although the ${(\mathrm{N}{\mathrm{O}}_{2})}^{\ensuremath{-}}$ anions are found to reorient rapidly, predominantly about the crystal $c$ axis, the simulation reveals the…
The Mossbauer spectra have been recorded from room temperature to above the Neel temperature for the spinel ferrites Cu 1-x Ni x Fe 2 O 4 and Cu 1-x Mn x Fe 2 O 4 for x=0.2, 0.4, 0.6 and 0.8. The spectra have been fitted with two sextets in the ferrimagnetic state. Iron is found to be in the trivalent high-spin state.…
ESR measurements on X-irradiated undoped CaSO 4 single crystals at 77K reveal two related radiation damage centres. Step annealing measurements suggest a connection between these centres and the thermoluminescent glow peaks at approximately 395 and 465K. An analysis of the g-values (centre I: g x =2.006, g y =2.0091 a…
The stiffness constants of a nematic liquid crystal are calculated for the situation of perfect orientational order with the aid of a model of distributed harmonic forces. Both attractive and repulsive forces are taken as distributed along the molecules, and thus are only important for the parts of two molecules that…
A novel geometry in which it is possible to do x-ray diffraction from a horizontal surface of fluids is applied to liquid crystals. A large-diameter drop of octyloxycyanobiphenyl (8OCB) on a glass plate treated for homeotropic alignment yields perfect alignment of the smectic-$A$ layers at the top surface over an area…
Abstract Isothermal crystallization of polypropylene in two temperature steps has been investigated by means of polarizing optical microscopy. On the edges of growing β‐spherulites a β → α modification change is observed when the temperature is raised beyond 140°C. The growth rate of the β‐modification exceeds that of…
Physical-chemical conditions of synthesis are found and trigonal GdF3-CaF2 crystals with Nd3+ ions are grown using the Bridgman technique. Detailed investigations are made of their spectroscopic intensity characteristics. Intermanifold luminescence branching ratios from the 4F3/2 state and transition cross-sections ar…
Variable range hopping conductivity (i.e. resistivity proportional to exp T−1/4) has been observed in Al implanted sapphire. The conductivity of these implanted layers was studied as a function of implanted doses.
We consider the interaction of electrons in unfilled shells of an ion substituted as an impurity in an insulating host crystal with their self-fields induced through polarizable ligands. All orders of the interaction (dipole, quadrupole, etc.) are considered, thereby extending previous treatments that included induced…