- Email: [email protected]
344. Electrical properties of single crystal nickel ferrites
Classified abstracts 341-353 device to regulate the breakdown current. This system greatly accelerates the pulse conditioning process and is economically viable. V V Steponov, USSR Patent, No 256,097, appl 28th June 1968, publd 24th March 1970. 33 341. Cathode. (USSR) A new version of an osmium-base cathode for electronic apparatus is proposed, which contains 0.5-35 at. % thorium and has a maximum secondary-emission coefficient of 2.05 with a work function of 3.23.3 eV. The cathode works at 1900°C. The secondary emission coefficient is lower than that of an iridium-thorium cathode but has a greater thermal stability, also being resistant to variations under electron bombardment. Having high electrical and thermal conductivities, the cathode may be operated at a high emission current density, while its smooth surface is an advantage in systems with narrow interelectrode gaps; it requires no prolonged activation. Possible uses include electron sources in magnetrons, electron beam tubes, and thermionic converters. The alloy may be prepared under an electric arc or in powder form. B Ch Dyubua et ul, USSR Patent, No 246,683, appl 13th March 1965, pubM 12th May 1970. 33 342. A metallic type of cathode. (USSR) A cathode made from alloys of noble metals (platinum, iridium) with alkaline earths (barium, strontium, calcium) containing 0.5-35 at. per cent of the latter is proposed. Such alloys contain Laves phases of the Pt=Ba, PtgSr, or Ir2Sr types, having a high thermionic-emission coefficient with substantial secondary emission (3-5) and great mechanical strength; they have a work function of 2.0-2.1 eV and operate at 1300°C, the evaporation of the active components being an order of magnitude lower than in conventional cathode materials. The alloys have a smooth, non-porous surface with metallic electrical and thermal conductivity; they may be prepared by melting the constituents in a protective atmosphere or by the ordinary methods of powder metallurgy. B Ch Dyubua et al, USSR Patent, No 246,684, appl lOth Dec 1965, pubM 12th May 1970. 37. METALLURGY, INORGANIC CHEMISTRY, ANALYTICAL CHEMISTRY 37 343. Investigation of the hydrogen content in steel. (Hungary) Factors influencing the hydrogen content in steel are studied. It is shown that the hydrogen and moisture contents in components of the charge, in additions, and in the furnace atmosphere, considerably affect the hydrogen content of the steel. The hydrogen content can be reduced in the course of steelmaking by appropriate choice of gas permeability of the slag and by intensive boiling. The deleterious influence of hydrogen can also be reduced or eliminated by the vacuum treatment of liquid steel, by addition of constituents that form hydrides and nuclei, by the preliminary dehydrogenation of the charge and alloying elements, by use of synthetic slags, and by reduction of the hydrogen content in the solid state, keeping it at high temperature. A comparison of the methods for determining the hydrogen content in steel revealed that the analysis data obtained by a vacuum exhalograph are lower than those given by heating tests, that there was no linear relation between the results of the two methods, and that the heating apparatus is more sensitive to variations of the hydrogen content during steelmaking. I Tar and L Hedai, Csepeli Muszaki Kozgazdasagi Szemle, 7 (1), 1969, 21-33 (in Hungarian). 37 344. Electrical properties of single crystal nickel ferrites. (USSR) The influence of thermal treatment in vacuum and in air on the temperature dependence of the electrical conductivity of single crystal nickel ferrites is studied. L I Ryabinkina et al, lzv Akad Nauk SSSR Ser Fiz, 34 (6), June 1970, 1176-1179 (in Russian). 37 345. The electrical conductivity of magnesium and manganese ferrites. (USSR) The influence of thermal treatment in vacuum and in air on the temperature dependence of electrical conductivity of magnesium and manganese ferrites is investigated. Experimental results are discussed. L I Ryabinkina et al, lzv Akad Nauk SSSR Set Fiz, 34 (6), June 1970, 1180-1182 (in Russian).
37 346. Exciton induced colour centre growth in KBr and KI crystals at 5 K. (Germany) Colour centres were created in KBr and KI at 5 K by ultraviolet irradiation, corresponding to the excitun absorption region and detected by luminescence methods. Measurements were carried out in an evacuated metal helium cryostat pumped by means of a charcoal absorption pump. (USSR) R Kink and G Lildja, Phys Stat Sol, 40 (1), July 1970, 379-387. 37 347. Plastic deformation of corundum single crystals. (Germany) The deformation characteristics and deformation mechanism of sapphire and ruby single crystals are studied in a special vacuum apparatus at pressures of 5 × 10-5 torr. The influence of chromium additive, crystallographic orientation, temperature and deformation rate is investigated. (USSR) M V Kiassen-Neklyodova et al, Phys Star Sol, 39 (2), June 1970, 679688. 37 348. The establishment of long-range order in Ni2Cr using electron microscopy. (Germany) Using selected area diffraction in transmission electron microscopy, long-range order has been clearly detected in the equilibrium phase of solid, nickel-rich, nickel-chromium alloy prepared by melting pure Ni and Cr under vacuum. The alloy must be given sufficient ageing, ranging from at least four months at 480°C to 600 hr at 500°C. (USA) H J Klein et al, Phys Stat Sol, 38 (2), April 1970, 831-836. 37 349. Transmission electron microscopy of point-defect clusters in neutron-irradiated metals. I. Copper. (Germany) Neutron-irradiated copper foils were investigated by means of transmission electron microscopy. The nature of the point-defect clusters was determined. It is shown that the large defects are predominantly of the interstitial type and the small defects are of the vacancy type. It was found that the defect type and the size distribution of the defects are influenced by the annealing atmosphere. Annealing in a dynamic vacuum at a pressure lower than 10-4 torr and in a reducing atmosphere have been tested. M Ruhle et al, Phys Stat Sol, 39 (2), June 1970, 609-620. 37 350. Transmission electron microscopy of point defect clusters in neutron-irradiated metals. H. Platinum. (Germany) Neutron-irradiated platinum foils 50 microns thick were investigated by means of transmission electron microscopy. The majority of the point defect clusters analyzed were found to be of the vacancy type. The effect of annealing the platinum at 1500°C in ultrahigh vacuum below 10-9 tort is investigated. M Ruble et al, Phys Star Sol, 39 (2), June 1970, 621-625. 37 351. The ~,-ray induced electric conductivity of fused silica as dependent on field strength, temperature and irradiation time. (Germany) The y-ray induced electrical conductivity of fused silica was studied theoretically and experimentally in high vacuum as a function of temperature, electric field strength, sample thickness and irradiation time. Gold electrodes were vacuum evaporated on to the sample. D Onnash, Phys Star Sol, 38 (2), April 1970, 579-592. 37 352. Principles of alloying semicondncting compounds with deviation from stoichiometry. (USSR) The microstructure and properties of G e T e + H g T e alloys prepared by alloying in an evacuated and sealed-off quartz, ampoules at a pressure of 10- ~ torr, are investigated. V M Glazov and V A Nagiev, Fiz Tekh Poluprovod, 4 (8), Aug 1970, 1536-1540 (in Russian). 37 353. Dislocation structure of nickel after load switching at low and ultrasonic frequencies. (USSR) Results are presented of an electron microscopic investigation of the dislocation structure of nickel heated in vacuum at 10 -s tort after loading at low and ultrasonic frequencies with direction changing. It is found that the mode of dislocation structure does not depend on loading frequency and that it is considerably altered by decrease of temperature. I A Giodin et al, Fiz Tverd Tela, 12 (8), Aug 1970, 2456-2458 (in
Russian). 197
37 346. Exciton induced colour centre growth in KBr and KI crystals at 5 K. (Germany) Colour centres were created in KBr and KI at 5 K by ultraviolet irradiation, corresponding to the excitun absorption region and detected by luminescence methods. Measurements were carried out in an evacuated metal helium cryostat pumped by means of a charcoal absorption pump. (USSR) R Kink and G Lildja, Phys Stat Sol, 40 (1), July 1970, 379-387. 37 347. Plastic deformation of corundum single crystals. (Germany) The deformation characteristics and deformation mechanism of sapphire and ruby single crystals are studied in a special vacuum apparatus at pressures of 5 × 10-5 torr. The influence of chromium additive, crystallographic orientation, temperature and deformation rate is investigated. (USSR) M V Kiassen-Neklyodova et al, Phys Star Sol, 39 (2), June 1970, 679688. 37 348. The establishment of long-range order in Ni2Cr using electron microscopy. (Germany) Using selected area diffraction in transmission electron microscopy, long-range order has been clearly detected in the equilibrium phase of solid, nickel-rich, nickel-chromium alloy prepared by melting pure Ni and Cr under vacuum. The alloy must be given sufficient ageing, ranging from at least four months at 480°C to 600 hr at 500°C. (USA) H J Klein et al, Phys Stat Sol, 38 (2), April 1970, 831-836. 37 349. Transmission electron microscopy of point-defect clusters in neutron-irradiated metals. I. Copper. (Germany) Neutron-irradiated copper foils were investigated by means of transmission electron microscopy. The nature of the point-defect clusters was determined. It is shown that the large defects are predominantly of the interstitial type and the small defects are of the vacancy type. It was found that the defect type and the size distribution of the defects are influenced by the annealing atmosphere. Annealing in a dynamic vacuum at a pressure lower than 10-4 torr and in a reducing atmosphere have been tested. M Ruhle et al, Phys Stat Sol, 39 (2), June 1970, 609-620. 37 350. Transmission electron microscopy of point defect clusters in neutron-irradiated metals. H. Platinum. (Germany) Neutron-irradiated platinum foils 50 microns thick were investigated by means of transmission electron microscopy. The majority of the point defect clusters analyzed were found to be of the vacancy type. The effect of annealing the platinum at 1500°C in ultrahigh vacuum below 10-9 tort is investigated. M Ruble et al, Phys Star Sol, 39 (2), June 1970, 621-625. 37 351. The ~,-ray induced electric conductivity of fused silica as dependent on field strength, temperature and irradiation time. (Germany) The y-ray induced electrical conductivity of fused silica was studied theoretically and experimentally in high vacuum as a function of temperature, electric field strength, sample thickness and irradiation time. Gold electrodes were vacuum evaporated on to the sample. D Onnash, Phys Star Sol, 38 (2), April 1970, 579-592. 37 352. Principles of alloying semicondncting compounds with deviation from stoichiometry. (USSR) The microstructure and properties of G e T e + H g T e alloys prepared by alloying in an evacuated and sealed-off quartz, ampoules at a pressure of 10- ~ torr, are investigated. V M Glazov and V A Nagiev, Fiz Tekh Poluprovod, 4 (8), Aug 1970, 1536-1540 (in Russian). 37 353. Dislocation structure of nickel after load switching at low and ultrasonic frequencies. (USSR) Results are presented of an electron microscopic investigation of the dislocation structure of nickel heated in vacuum at 10 -s tort after loading at low and ultrasonic frequencies with direction changing. It is found that the mode of dislocation structure does not depend on loading frequency and that it is considerably altered by decrease of temperature. I A Giodin et al, Fiz Tverd Tela, 12 (8), Aug 1970, 2456-2458 (in
Russian). 197