Local laser-induced change of optical properties in the bulk of photochromic porous silicate glass doped by silver and copper halides

The principles of the formation of modified areas of a spherical shape and complex structure in porous glass plates doped by silver and copper halides under the continuous radiation of a fiber laser focused inside the plate have been formulated. The results of the study of the obtained modified areas are given.     

Thermochemical stability of Fe- and co-functionalized perovskite-type SrTiO3 oxygen transport membrane materials in syngas conditions

The materials typically used for oxygen transport membranes, Ba_0.5Sr_0.5Co_0.8Fe_0.2O_3?δ (BSCF) and La_0.6Sr_0.4Co_0.2Fe_0.8O₃ (LSCF) tend to decompose due to their low thermochemical stability under reducing atmosphere. Fe- and Co-doped SrTiO₃ (SrTi_1-x-yCo_xFe_yO_3-δ, x + y ≤ 0.35) (STCF) materials showing an oxygen transport comparable to LSCF have great potential for application in ion-transport-devices. In this study, the thermochemical stability of pure perovskite-structured STCF was investigated after annealing in a syngas atmosphere at 600–900 °C. The phase composition of the materials after annealing was characterized by means of X-ray diffraction (XRD). The thermodynamic activities of SrO, FeO, and CoO in the STCF materials were evaluated using Knudsen effusion mass spectrometry (KEMS). Co-doped SrTiO₃ (STC) materials were not stable after annealing in the syngas atmosphere above 5 mol% Co-substitution. Ruddlesden-Popper-like phases and SrCO₃ were detected after annealing at 600 °C. In contrast, Fe substitution (STF) showed good stability after annealing in syngas upto 35 mol% substitution.     

Boron Nitride with Packets of Nanotubes for Microcomposite Ceramics

The possibility of creating microcomposite technical ceramics based on boron pyronitride (BPN) with nanotubes and packets of nanotubes providing a high microplasticity is considered. It is shown that the irradiation by nanosecond proton-ion beams with a high powder density promotes the growth of wurtzite-like BPN based on self-organizing mesoscopic (SOM) particles, SOM-blocks, and nanocrystalline particles. The sizes of SOM-particles and SOM-blocks of the initial and irradiated BPN are determined. The self-organization of nanotubes outside the zone of irradiation has a spiral cyclic nature and is caused by shear deformations of the layers composed of SOM-blocks. Tubes inclined to the surface with symmetry axes of the fifth order and packets of nanotubes of a disk shape are observed. The obtained micrographs are compared with model forms of manifestation of spiral cyclic structures.     

Computer simulation of microcomposite ceramics with high transcrystalline mobility

Computer simulation is used to consider the possibility of creation of microcomposite technical ceramics with a high transcrystalline mobility and to show that allowance for the exchange interactions of atoms through nonequilibrium electrostatic fields causes formation of self-organized mesoscopic (SM) blocks, which provide microplasticity and relaxation of strain at lower temperatures. The simulation results agree with the yield stria observed in mechanical compression tests of A1₂,O₃ specimens obtained from sol-gel solutions. It is shown that the yield stria are directly connected with the sizes of the SM blocks. The high mobility of SM blocks also promotes a decrease in the temperature of the gel → A1₂O₃ transformation.     

Monitoring of the current-distribution uniformity in bipolar transistors from the dependence of internal-feedback factor on collector voltage

On the basis of the two-section model of a high-power bipolar transistor, it is shown that the slope of dependence of the small-signal feedback coefficient on the collector voltage in the presence of defects in the transistor is proportional to the defect size. The setup for the automated monitoring of the current-distribution nonuniformity in the transistor device structure from the indicated dependence with using the combination of linearly increasing and small harmonic variations in the collector voltage is described. The experimental dependences confirming the results of the theoretical analysis are presented.     

Anodic oxidation of iron during the purification of sulfate zinc solutions

The anodic oxidation of iron in zinc solutions is carried out using a two-chamber electrolyzer separated by an anionite membrane. The positive effect that copper ions in the solution have on the rate and completeness of the oxidation processes is shown. This method is effective for cleaning the solutions of zinc production and processing the industrial zinc-containing wastes.     

Influence of the structure factor of P/M materials on the strength and plastic properties of type VK detonation coatings

Translated from Poroshkovaya Metallurgiya, No. 11 (347), pp. 24–30, November, 1991.     

Leaching of lead cakes of zinc production in a complexing solvent

The process of leaching of lead cakes of zinc production in a complexing solvent—trilon B, which makes it possible to selectively extract lead into the solution—is studied with the use of mathematical modeling of the experiment. Its optimum conditions—pH, liquid-to-solid ratio within pulp, and temperature—are determined. The developed flow chart of cake processing provides zinc removal as a single product, recycling of zinc to the basic production, and reduction of current expenditure due to solvent regeneration.