Synthesis and Properties of NdMCr2O5 (M = Na, K, Cs) and NdMgCr2O5.5 Chromites

NdMCr₂O₅ (M = Na, K, Cs) and NdMgCr₂O_5.5 are prepared by solid-state reactions between appropriate oxides and carbonates and are shown to have a tetragonal structure. The heat capacity of these chromites, measured from 298.15 to 673 K, exhibits sharp changes attributable to second-order phase transitions. The C _p ⁰(T) data are represented by quadratic best fit equations. The electrical resistivity of the chromites is measured between 303 and 493 K. The results attest to semiconducting behavior of the materials in certain temperature ranges.     

Ultrasonic treatment restores the photoelectric parameters of silicon solar cells degraded under the action of <Superscript>60</Superscript>Co gamma radiation

The photoelectric parameters of silicon solar cells degraded under the action of ⁶⁰Co gamma-radiation can be partly restored using an ultrasonic treatment (UST). The growth of the maximum output power of solar cells after the UST is related to a redistribution of the radiation defects and an increase in the homogeneity of a semiconductor crystal structure.     

Relaxor Behavior of Ge-Doped TlInS2

The dielectric and pyroelectric properties of Ge-doped (0.1 mol %) TlInS₂ crystals are studied. The results demonstrate that TlInS₂ is a ferroelectric relaxor. The experimental data are used to evaluate, using the Vogel–Fulcher relation, the activation energy (0.045 eV), preexponential factor (f ₀ = 2 × 10¹³ Hz), and the dipole-freezing temperature (T _F = 142 K) and to determine the temperature range of the stable relaxor (nanodomain) state and the temperature of the transition to the ferroelectric (macrodomain) state, accompanied by an anomaly in the temperature-dependent pyroelectric coefficient.     

Electrolyte—solvent interaction in the dipolar aprotic solvent dimethyl sulphoxide at 25°C

Conductance measurements are reported for s-alkylisothiouronium bromide, iodide and picrate salts in the dipolar aprotic solvent DMSO at 25°C. The data were analysed by Fuoss's equation (1975–1980) for 1:1 electrolytes, from which the values of Λ₀, the Gurney's cosphere diameter R and K_A are obtained. The results are discussed in the light of the recorded values of the constants K_R and K_S and the free energy term G_s.     

Electromagnetic precursor of rock collapse

Polytechnic Institute, Tomsk. Translated from Fiziko-Tekhnicheskie Problemy Razrabotki Poleznykh Iskopaemykh, No. 2, pp. 6–11, March–April, 1993.     

Movement stability analysis of a pipe string in a thixotropic fluid

Features of movement of a drill pipe string in a well filled with a thixotropic fluid are analyzed taking into account inertial and elastic forces of the rope system. It is shown that processes of fluid structure degradation can lead to nonstationary movement of the pipes. In this case periodic and chaotic auto-oscillations are excited in the system.Bashkir State University, Ufa, Russia. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 66, No. 4, pp. 405–411, April, 1994.     

Vapor phase synthesis of ZnO structures

We observed zinc oxide structures formed in an oxygen-containing atmosphere as a result of oxidation of the surface of zinc droplets. The gas-phase oxidation leads to the formation of hollow ZnO whiskers on the metal surface, which grow due to the transport of zinc vapor through their channels. It was found that high partial pressures of zinc and atomic oxygen give rise to fractal structures, which appear in a cascade process involving the sequential formation of zinc oxide vapor, ZnO clusters, and cluster aggregates as a result of the cluster-cluster interaction. A deposit of ZnO synthesized on the cathode surface exhibits a columnar structure.     

Fish protection in medium and large open water intakes

A new layout of a fish-protecting facility is proposed. __________ Translated from Gidrotekhnicheskoe Stroitel’stvo, No. 12, December 2006, pp. 24–26.     

Features of the photoconductivity of iodine-doped cotton fibers illuminated in the fundamental absorption range

The photoelectric properties of cotton fibers treated with iodine were studied in the fundamental absorption range. The samples exhibit a sublinear illumination-current characteristic and a long-term relaxation of photoconductivity (PC) after UV irradiation (hν=5 eV) of the iodine-doped fibers. A PC mechanism is proposed which explains both the nonlinear variation of photocurrent with illumination intensity and the PC decay according to a bimolecular recombination law after UV irradiation of the iodine-doped fiber in the fundamental absorption range.