The electrical conductivity of the surface layers of oxide polycrystalline semiconductors irradiated by accelerated ions

The effect of ion irradiation on the electrical conductivity of low resistance and high resistance subsurface layers of polycrystalline Li-Ti ferrites is studied. Irradiation was carried out with accelerated Ar+ ions with energy E=150 keV and the fluence F=10{16} ions/cm{2}. It is found that exposure of high-resistance ferrites significantly decreases the activation energy E? and considerably increases the electrical conductivity of the surface layers. The effect of the ion beam on the stated low-resistance characteristics of the samples is much weaker. The observed decrease in the numerical values of E[sigma] is due to the decrease in the values of the intergranular potential barrier caused by the exposure. The decrease in the potential barrier difference is due to the decreased degree of the grain boundary oxidation which is caused by preferential desorption of oxygen under the action of the ion beam. The thermal stability of the electrical characteristics of the investigated ferrites subjected to ion radiation-induced modification is determined

Influence of an initial chemical state of bivalent cation impurities on their diffusion activity in alkali-halide crystals

Influence of an initial chemical state of bivalent cation impurities on their diffusion activity in alkali-halide crystals is investigated. The effect of an intensive electron beam on diffusion of magnesium impurity in crystals of fluoride of lithium is studied

Physics and chemistry of producing silicon-hydroxylapatite-titanium composite materials

In the research, Si-HA poweders have been synthesized using SBF solution with different content of silicon. It was found that all the samples synthesized from the model solution of extracellular fluid under varying concentration of silicate ions are single-phase and repesent hydroxyapatite. The nature of the reagent containing SiO[44]- ions does not affect the hydroxyapatite structure. In the study of the surface and morphological characteristics of the phosphate coatings modified by silicon ions, it was found that as the degree of phosphate calcium substitution by SiO[44]- ions increases, the surface wettability on the titanium substrates deteriorates and cohesive energy decreases. It is shown that the titanium coating is formed in three stages. After irradiation of titanium substrates coated with Si-HA, the crystals can keep growing and the surface can keep regenerating

Sintering of zirconia ceramics using microwave and spark heating techniques

The paper presents the results of an complex study of structural and mechanical properties of zirconia ceramics sintered using different techniques. The samples were sintered via the conventional method of heating, in the field of microwave radiation and spark plasma. The experimental data indicates that a microwave field and spark plasma have a stimulating effect on zirconia ceramics sintering. In contrast to the microwave sintering, spark plasma sintering provides ceramics with improved properties at similar time-temperature annealing modes. Moreover, the properties of the ceramics under spark plasma sintering at T=1300 °C are similar to the properties of the ceramics sintered in a microwave field at T=1400 °C

Effect of ion-plasma treatment on oxidation-reduction processes in lithium-titanium-zinc ferrites

We examined the effect of nitrogen, oxygen and argon plasma on the diffusion-controlled oxidation-reduction processes in lithium-titanium-zinc ferrite ceramics by measuring the activation energy of electrical conductivity in the depth of the sample. The experimental results show that the high-temperature treatment in polycrystalline ferrites by nitrogen or argon ion plasma greatly accelerates the oxidation-reduction processes in ferrites and changes the process direction depending on the partial pressure of oxygen

Deformation characteristics of the near-surface layers of zirconia ceramics implanted with aluminum ions

The effect of ion treatment on the phase composition and mechanical properties of the near-surface layers of zirconium ceramic composition 97 ZrO[2-3]Y[2]O[3] (mol%) was studied. Irradiation of the samples was carried out by accelerated ions of aluminum with using vacuum-arc source Mevva 5-Ru. Ion beam had the following parameters: the energy of the accelerated ions E=78 keV, the pulse current density J[i] = 4mA/cm{2}, current pulse duration equal tay=250 mcs, pulse repetition frequency f=5 Hz. Exposure doses (fluence) were 10{16} и 10{17} ion/cm{2}. The depth distribution implanted ions was studied by SIMS method. It is shown that the maximum projected range of the implanted ions is equal to 250 nm. Near-surface layers were investigated by X-ray diffraction (XRD) at fixed glancing incidence angle. It is shown that implantation of aluminum ions into the ceramics does not lead to a change in the phase composition of the near-surface layer. The influence of implanted ions on mechanical properties of ceramic near-surface layers was studied by the method of dynamic nanoindentation using small loads on the indenter P=300 mN. It is shown that in ion- implanted ceramic layer the processes of material recovery in the deformed region in the unloading mode proceeds with higher efficiency as compared with the initial material state. The deformation characteristics of samples before and after ion treatment have been determined from interpretation of the resulting P-h curves within the loading and unloading sections by the technique proposed by Oliver and Pharr. It was found that implantation of aluminum ions in the near-surface layer of zirconia ceramics increases nanohardness and reduces the Young's modulus

Diffusion mass transfer in ionic materials under intense electron irradiation

The results of studies on the impact of an electron beam with the energy of 1-2 MeV on diffusion processes in materials with ionic bonds are presented in the paper. Used electron beam intensity is allowed to provide heating of the material to temperatures of 1600 K. Diffusion of Na, Mg, Al ions into single crystals KBr in the temperature range 573-883 K, Al ions in the NiO-AlO system at 1373-1573 K, was studied. Diffusion annealing carried out under thermal and radiation-thermal heating of the samples. Then diffusion coefficients were determined. It was found stimulating action of irradiation on diffusion processes of Mg, Al ions in Kbr and Al ions in the NiO-Al[2]O[3] system, which consists in increasing the diffusion coefficients at radiation-thermal annealing. The observed effect is achieved by increasing the effective rate of diffusion jumps