Mictomagnetic behaviour in MnAlC(Ni) alloys

The as cast, thermally treated and hot extruded Mn_1.058Al_0.909C_0.022Ni_0.011 samples were investigated by X-rays, neutron diffraction and magnetic measurements. The hot extruded magnets produced by Matsushita Electric Ind. Co., having (BH)_max = 5 MGOe, show a mictomagnetic-type behaviour.     

Martensitic transformations in Ti (Ni,Fe) alloys

In this work we used x-ray structural analysis to investigate the martensitic transformations (MTs)B2R andRB19 in Ti(Ni, Fe) alloys containing 1, 2.5, 4, 5 at. % Fe, and the effect of heat treatment on the MT temperatures and sequence. In the majority of cases, it was found that the MTB2R proceeds through a two-phase region (+R). Heat treatment leads to a narrowing of the temperature interval of the existence of the two-phase region, weakly affects the onset temperatures of the MTsB2R T_R andRB19 M_s, and sharply increases the temperature-of the end of the MT M_e. The existence of the two-phase region is related to the two MT channelsB2R andB2B19 initially intrinsic to the allovs of the given compositions.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 12, pp. 19–22, December, 1989.     

Anisotropy of spin wave dispersion relations in Ni (Fe) alloys

Spin wave dispersion relations were measured in Ni (Fe) samples grown in a magnetic field. Anisotropy of the stiffness constant was observed. The effect can be qualitatively explained by the existence of directional anisotropy.     

Investigation of electronic configurations of Ni3(Fe,Ti) and Ni3(Mn,Ti) alloys

The ordinary Hall constant R_o of quenched Ni₃(Fe, Ti) and Ni₃(Mn, Ti) alloys was measured. The number of 4s and 3d electrons per atom was calculated on the basis of a four-band model. At low Ti concentrations in Ni₃(Fe, Ti) the contribution of 3d holes to R_o is negligible, but at high concentrations it is significant. The contribution of 3d holes to R_o for Ni₃(Mn, Ti) is considerable, and for Ni₃Mn and Ni₃(Mn +9.8% Ti) it is dominant. It is concluded that the changes in band energy of the bond between Ni and Ti in the considered systems are of a different nature.Deceased.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 5, pp. 12–14, May, 1981.     

Investigation of the electronic characteristics of Ni3 (Fe,Ti) and Ni3 (Mn,Ti) alloys

The anomalous Hall (R_s) and the Nerst-Ettingshausen (Q_S) constants are measured for hardened Ni₃ (Fe, T_i) and Ni₃ (Mn, Ti) alloys. Scattering by phonons is detected, con tributing primarily to R_S as compared to scattering by magnetic inhomogeneities. Based on the positive signs of R_g and Q_S, it is concluded that 3d holes wi th antiparallel spin make the main contribution to the conductivity. A model is proposed for the electronic structure of the alloys studied.DeceasedTranslated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 6, pp. 59—63, June, 1981.     

Cation diffusion,semiconductivity and nonstoichiometry in (Co,Ni)O crystals

The diffusivities of ⁶⁰Co and ⁵⁷Ni, and the electrical semiconductivity in (Co,Ni)O crystals have been determined as a function of temperature and composition in an air atmosphere. Both ⁶⁰Co and ⁵⁷Ni diffuse by a vacancy mechanism. Their diffusivities increase exponentially with an increase cation fraction of cobalt in the mixed oxides at a constant temperature. Using Manning's model of diffusion in a random alloy, the relative extent of off-stoichiometry and, therefore, the concentration of cation vacancies relative to NiO as a function of c in (Co_cNi_1?c)O were evaluated from the diffusion data. The change in enthalpy of formation of a cation vacancy as a function of the cation composition in mixed oxides has also been deduced from the experimental results. From a comparison of the cation composition dependency characteristic of the electrical semiconductivity with that of the cation vacancy cocentration, it was deduced that the apparent number of effective negative charge on a cation vacancy varies almost linearly from two in NiO to almost unity in CoO. Interdiffusion experiments show that a net flow of cations in one direction in a CoO?NiO diffusion couple will produce a gradient in the oxygen activity that can alter the diffusion behavior of the sample.     

Hall effect in the ternary ordered alloys Ni3(Mn,Fe) and Ni3(Mn,Co) 1. Disordered solution solutions

The normal and anomalous Hall constants R₀ and R_s, respectively, and the resistivity have been measured for the quasibinary alloys Ni₃Mn-Ni₃Fe and Ni₃Mn-Ni₃Co. The results imply that in ternary alloys of Ni₃Mn containing slight Fe and Co impurities the hole regions of the Fermi surface make an important contribution to R₀ and that the primary scattering mechanism for the carriers corresponding to the anomalous Hall current in the alloys with Fe at room temperature is phonon scattering. It is concluded that the Fermi surface of the Ni₃Mn-Ni₃Fe alloys is closed.Translated from Izvestiya VUZ. Fizika, No. 3, pp. 21–29, March, 1970.     

Hall effect in the ternary ordered alloys Ni3(Mn,Fe) and Ni3(Mn,Co) II. Ordered solid solutions

An experimental study was made of the changes in the normal and anomalous Hall constants R₀ and R_s, respectively, the internal saturation induction B_s, and the resistivity ? during the ordering of quasibinary Ni₃Mn-Ni₃Fe and Ni₃Mn-Ni₃Co alloys. The concentration dependences of R₀, R_s, B_s, and ? were also studied in the ordered state of these alloys. It is concluded from an analysis of the experimental results that the decreases inR₀ and ? during the ordering of Ni₃Mn and as a result of the alloying of ordered Ni₃Mn with slight amounts (～5 at. %) of iron are due primarily to a decrease in the hole contribution to transport and to a decrease in the state density in the 3d band of these alloys near the Fermi level. The experimental data are in satisfactory agreement with the curve calculated by Yamashita et al. [6] for the density of 3d states in ordered Ni₃Mn and Ni₃Fe alloys.     

Trapping and diffusion mechanism in aluminum alloys

We have studied Al(Cu), Al(Mg) and Al(Ag) alloys to determine the μ⁺ trapping sites, and how impurity distortions affect these sites. Cu (Monovalent) contracts the Al lattice, Mg (divalent) expands it, and Ag (monovalent) has almost no effect. Fitting to a two-state model we obtained a temperature exponent β of 0.93 (26 for zero field and 1.16(14) for a longitudinal, field where β=1 implies a one-phonon induced diffusion process. The measured secon moment in Al(Mg) indicates a changing trapping site, which was confirmed by zero and longitudinal field studies. Comparing the Al(Mg) results with earlier Al(Cu) data, two types of sites can be identified: those which are distant from the defect and depend on the magnitude but not the sign of the deformation, and those close to Mg. Ag produces no lattice distortion, and its weaker depolarization suggests a different trapping mechanism.     

Structural defects in Ni-Ti alloys in the region of B2-phase homogeneity

A comparison is made of the x-ray and pycnometric densities of Ti-Ni alloys, with a high nickel content relative to the equiatomic composition, when the alloys are quenched outside the region of -phase homogeneity. An analysis is made of the possibility of the formation of vacancies, interstitial atoms, triple defects, and substitutional defects in the alloys. It is concluded that substitutional defects are formed: nickel atoms which are excess atoms relative to those found at the lattice points in the CsCl superstructure are located in the titanium sublattice. An evaluation showed that in the formation of alloys near the equiatomic composition of TiNi, the atomic volumes of titanium and nickel are about 1.8 and 7.4% smaller than for the pure components, respectively.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 11, pp. 45–50, November, 1987.     

Surface diffusion of Ni on Si(111) with coadsorption of Co

The effect of the coadsorption of Co and Ni on an Si(111) surface structure and on the diffusion of adsorbed atoms is investigated by low-energy electron diffraction and Auger electron spectroscopy. It is established that surface structures similar to those formed with the adsorption of Co alone are formed with the Ni and Co coadsorption on an Si(111) surface. It is found that the contribution of surface diffusion to the transport of Ni atoms is sharply higher on an Si(111) surface with submonolayer Co concentrations in the temperature range 500–750 °C than for a pure surface, where the main mechanism of Ni transport along the surface is diffusion of Ni atoms through the bulk of Si. Fiz. Tverd. Tela (St. Petersburg) 41, 1489–1494 (August 1999)     

X-ray photoelectron spectroscopy of Ni in Ni–Zn and Ni–Al alloys

X-ray photoelectron spectroscopy measurements on Ni in the alloys Ni, Ni₅₀Zn₅₀, Ni₂₀Zn₈₀ and Ni₅₀Al₅₀ have been made and confirm previous measurements of the band structure. The satellite lines on the Ni 2p and 3s lines are found to be present in the spectra even when the density of 3d states at the Fermi energy is low.     

Investigation of electrical resistivity and average magnetic moment per atom of Ni3(Fe,Ti) and Ni3(Mn,Ti) alloys

The electrical resistivity and average magnetic moment per atom of Ni₃(Fe, Ti) and Ni₃(Mn, Ti) alloys were measured. X-ray structural analysis revealed the presence of the Ni₃Ti phase in Ni₃(Fe+7% Ti) and Ni₃(Fe + 10.3% Ti), and strong interaction of Ni and Ti is deduced. The introduction of Ti into Ni₃Mn reduces the antiferromagnetic Mn-Mn interaction and thus leads to greater ordering.Deceased.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 5, pp. 9–12, May, 1981.     

Spontaneous resistivity anisotropy in Ni alloys

We present experimental results for the resistivity anisotropy of Ni alloys containing transition impurities. From these results and those of other authors, we show that the Smit spin mixing mechanism is dominant in all cases where there is no d virtual bound state at the spin ↑ Fermi level. When such a state is present, an additional mechanism due to the L_zS_z part of the spin-orbit interaction must be included in the analysis.