The processes of the accumulation and annealing of radiation-induced defects that occur under low-temperature (at 77 K) irradiation (with an energy E > 0.1 MeV) of V−4Ti−4Cr and V−10Ti−5Cr bcc alloys both nonmodified and modified with hydrogen isotopes in a concentration of 200 ppm, as well as the effect of these processes on the physicomechanical properties of these alloys, have been studied. It has been found that the saturation of these alloys with hydrogen leads to slight changes in their strength and ductility characteristics. The irradiation of the alloys at the temperature of 77 K results in a substantial increase in their yield stress and ultimate strength, as well as a decrease in their ductility. In the course of the postradiation annealing of the alloys at a temperature of 130 K, the stage related to the migration of interstitial atoms is observed. At temperatures of 290–320 K, the recovery stage occurs due to the formation of vacancy clusters. The stage that occurs at a temperature of 470 K can be attributed to the formation of impurity-vacancy clusters. Possible mechanisms of the radiation-induced strengthening of the alloys during irradiation and subsequent annealing have been discussed.

The effect of hydrogen, accumulation and annealing of radiation defects on the physicomechanical properties of an austenitic Kh16N15M3T1 steel (16Cr15Ni3Mo1Ti) has been investigated upon low-temperature (77 K) neutron and electron irradiations. It has been shown that, when its concentration is about 300 at ppm, hydrogen reduces plasticity by 25%. The presence of helium (2.0–2.5 at ppm) introduced by the tritium-trick method exerts an effect on the yield strength and hardly affects embrittlement. Upon both electron and neutron irradiation, there is a linear relation between the increment of the yield strength and the square root of the increment of the residual electrical resistivity (the concentration of radiation defects). The annealing of vacancies occurs in the neighborhood of 300 K (energy for vacancy migration is 1.0–1.0 eV). Vacancy clusters dissociate near 480 K (energy for dissociation is 1.4–1.5 eV).

Complex investigations of radiation damage of Ni and Ni- 880 at. ppm C alloy under electron and neutron irradiation in the region of room temperature hardened and deformed state. In pure nickel, with the deformation microstructure, both in electron and in the neutron irradiation is observed separation of radiation-induced defects. When electron irradiation in the alloy Ni-C separation effect is observed, and when neutron irradiation there is no. This is due to the interaction of carbon atoms with radiation defects. The main sinks for radiation-induced defects are the areas with a high concentration of defects in cascades of atomic displacements.

The effect of pressure up to 22 GPa on the electrical resistance and thermopower of lanthanum monobismuthide at room temperature has been studied. A semiconductor-metal phase transition in the pressure range of 4–6 GPa has been revealed from the change in the sign of thermopower and the thermal dependence of the electrical resistance of LaBi. The observed inflections in the pressure dependences of the thermopower and electrical resistance of LaBi samples in the pressure range of 8–11 GPa can be ascribed to the structural phase transition from the B 1 phase to the PT and B 2 phases.

It is shown that lanthanum monochalcogenides (LaS, LaSe, LaTe), in which metal ions are trivalent at least up to 22 GPa, may be used as reference materials in finding the stability domains of a variable-valence state in rare-earth elements in different compounds studied under pressure. The thermopower of these materials throughout the pressure interval studied varies between 1 and 4 μV/K.

The electrical resistivity, the Hall effect, the free charge carrier mobility, and their field dependences have been studied in lanthanum monobismuthide (LaBi) over the temperature range of 1.7–300 K in magnetic fields to 13 T. For comparison, similar measurements have been performed on samples of lanthanum monotelluride (LaTe). It has been shown that LaBi is a semiconducting material with a complex structure of the conduction band.

Pure nickel, the model material for austenitic steels used in reactors, with an electrical resistivity ratio of ρ300 K/ρ4.2 K ∼ 300 has been investigated under electron and neutron irradiation at T IRR ∼ 320–340 K. Three of its states have been subjected to irradiation: a recrystallized state at 873 K, a deformed one to 90%, and an annealed one at 450 K after deformation to remove deformation-induced vacancies. It is has been experimentally shown that neutron and electron irradiation of the deformed nickel results in the separation of radiation-induced defects. This separation occurs because a significant portion of the radiation-induced interstitial atoms is captured by dislocation sinks and does not participate in recombination with vacancies. As a result, the concentration of accumulated vacancies in the deformed nickel can exceed their concentration in the annealed nickel and be almost twice as high. At higher doses of neutron irradiation, above 1018 cm−2, separation does not occur, since vacancy sinks in the form of clusters are more powerful than dislocation sinks.

Using examples of some perspective electronic materials (HgSeS, Fe3O4, InN, and others) it is shown that magnetoresistance data at high magnetic fields allow evaluating the true values of mobility of charge carriers in spite of any "adverse factors". Additional impacts involving high pressure and irradiation with high-energy particles (neutrons, electrons, ions) produce the enhancement of magnetoresistance technique of testing and allow to go into details of the type of electron structure and scattering mechanisms of charge carriers.

The influence of atomic disorder induced by irradiation with fast neutrons on the properties of normal and superconducting states of polycrystalline samples of FeSe has been studied. The irradiation with fluences of fast neutrons up to 1.25 × 10 20 cm −2 at the irradiation temperature T irr ≈ 50°C leads to relatively small changes in the temperature T c of the superconducting transition and in the electrical resistivity ρ 25 at 25 K. This behavior is related to the relatively low concentration of radiation defects arising at a given irradiation temperature, which is a consequence of a specific crystal structure of FeSe, which is more simple as compared to other layered compounds of this class.

Single crystals FeSex were grown in an evacuated sealed quartz tube using polycrystalline material by gas-transport reaction with I2 as a gas-carrier. Crystals with hexagonal-prismatic, tetragonal-prismatic, planar-square and hexagonal faceting 0.1 to 0.5 mm in size were obtained. The electronic transport and magnetic prop-erties measurements of FeSex single crystal exhibit an onset of superconducting transition Tc at up to 24 K.

The processes of accumulation and annealing of radiation defects at low-temperature (77 K) electron and neutron irradiation and their effect on the physicomechanical properties of Fe-Cr alloys and oxide dispersion strengthened (ODS) steel have been studied. It has been shown that the behavior of radiation defects in ODS steel and Fe-Cr alloys is qualitatively similar. Above 250 K, radiation-induced processes of the solid solution decomposition become conspicuous. These processes are much less pronounced in ODS steel because of specific features of its microstructure. Processes related to the overlapping of displacement cascades under neutron irradiation have been considered. It has been shown that, in this case, it is the increase in the size of vacancy clusters, rather than the growth of their concentration, that is prevailing. Possible mechanisms of the radiation hardening of the ODS steel and the Fe-13Cr alloy upon irradiation and subsequent annealing have been discussed.

The experimental data concerning the effect of hydrogen (300 appm), radiogenic helium, and low-temperature neutron irradiation (77 K) on the properties of the promising austenitic 16Cr15Ni3Mo1Ti and austenitic-martensitic 16Cr9Ni3Mo steels have been reported. It has been found that hydrogen saturation causes an increase in the yield stress, with this increase being larger in the martensitic than in the austenitic phase. The yield stress of both steels increases substantially after exposure to fast neutrons. The variation of the yield stress of the two-phase steel and its phase components under low-temperature neutron irradiation has been estimated. The displacement cascades begin overlapping under irradiation at a fluence larger than 1.5 × 10 18 cm −2 .

The Fe x TiTe2 system, which belongs to the class of materials with the electronic spectrum containing below the Fermi level the band of localized states with a strong temperature dependence of the band width, has been investigated experimentally. Heating of the material leads to a broadening of the band of localized states. When the top of this band crosses with the Fermi level, the effect of retrograde solubility is observed in the system; i.e., the metal precipitates to the composition ensuring the absence of increase in the Fermi energy during heating. The influence of the band of localized states on the structure of the material and its magnetic and electrical properties has been analyzed.

The results of synthesizing a new layered phase—nickel oxybismuthide LaO 1−δ NiBi in a series of superconducting oxypnictides—and its properties in the superconducting and normal states are reported. Although the temperature of the transition of this phase to the superconducting state, T c ∼ 4 K, is much lower than the value T c = 55 K reached at present in oxyarsenide SmO 1−δ FeAs, the similarity of the crystal structures and ρ( T ) dependencies indicates that the mechanism responsible for the appearance of the semiconducting state is the same in lanthane oxybismuthide and samarium oxyarsenide.

The Pb-207 NMR spectra and the rates of spin-lattice relaxation were measured in a temperature range of 10-100 K using the superconducting oxide BaPb0.88Bi0.12O3(T-c(phi(n)=0)=6K)subjected to structural disordering by a flux of fast neutrons (T-irr = 350 K, E-n similar to 2 MeV, phi(n) = 1.3 x 10(19) cm(-2)). The shape of the NMR line of Pb-207 is determined by the Knight-shift distribution (whose magnitude is proportional to the local spin susceptibility X, of the conduction-band electrons) over the crystal. The spectrum fine structure arising upon disordering indicates the formation of nonconducting microregions that are, presumably, located near the neutron track. In the metallic regions of structural relaxation that are far from the neutron track, the relative decrease in the local spin density of charge carriers (Delta chi(s)/chi(s) similar to 0.15)is insufficient to explain a substantial suppression of the critical temperature of the superconducting transition of the oxide T-c(phi(n) = 1.3 x 10(19) cm(-2)) < 4 K obtained in terms of the models of uniformly disordered systems.

In this paper, the influences of fast neutron bombardment, high pressure and chemical substitution on the electronic properties of PbSe single crystals are studied. For the first time in p-PbSe an electronic transition has been established of 'metal-semiconductor' type accompanied by an increase of resistivity of several orders of magnitude under the action of fast neutron bombardment. A similar increase in electrical resistance R was observed also under application of high pressure P above similar to 3-4 GPa. The last increase was associated with the phase transformation from the NaCl-lattice to the GeS-lattice, which was seen also in sharp jumps of thermopower S. From the R (P) and S(P) dependences a linear decrease has been found of pressure of the above phase transition with increase of < Sn > content for n-Pb1-xSnxSe (x = 0.06, 0.08, 0.125) compounds.

The temperature dependences of the electrical resistivity ρ(T) and the ac magnetic susceptibility χ(T, H = 0) are thoroughly investigated for a perovskite-like lanthanum manganite, namely, La0.85Sr0.15MnO3, which is preliminarily exposed to neutron irradiation with a fluence F = 2 × 1019 cm−2 and then annealed at different temperatures ranging from 200 to 1000°C. The results of the electrical resistance measurements demonstrate that neutron irradiation of the samples leads to the disappearance of the low-temperature insulating phase. As the annealing temperature increases, the insulating phase is not restored and the manganite undergoes a transformation into a metallic phase. Analysis of the magnetic properties shows that, under irradiation, the ferromagnet-paramagnet phase transition temperature TC decreases and the magnetic susceptibility is reduced significantly. With an increase in the annealing temperature, the phase transition temperature TC and magnetic susceptibility χ(T, H = 0) increase and gradually approach values close to those for an unirradiated sample. This striking difference in the behavior of the electrical and magnetic properties of the radiation-disordered La0.85Sr0.15MnO3 manganite is explained qualitatively.

Using neutron diffraction, X-ray diffraction, and magnetic measurements, we studied the structural and magnetic states of polycrystalline samples of the manganite La0.8Ba0.2MnO3 before and after fast-neutron and irradiation to a fluence of 3 x 10(20) cm(-2). The irradiated manganite is found to be inhomogeneous and to contain an amorphous phase, a partially disordered cubic phase (space group Pm3m), and an initial rhombohedral phase (space group R (3) over barc). Actually, the structural state detected after irradiation is a "frozen" incomplete transition from the amorphous into the initial crystalline state, and this state is controlled by the concentration of "antisite" defects in any of these phases. The radiation-induced structural transformation is shown to lead to the transformation of the initial collinear ferromagnetic ordering (T-C = 275 K) into spin-glass ordering (T-f = 35 K). The main cause of the change in the magnetic state of the manganite is shown to be the destruction of the double ferromaonetic exchange and the frustrations of the negative exchange interactions during structural disordering.