[en] The thermal expansion and forced volume magnetostriction of Zr(Fesub(1-x)Cosub(x))₂ have been measured. The results indicate that the magnetovolume coupling between spontaneous volume magnetostriction and spontaneous magnetisation is very large and is almost independent of the concentration of Co in the ferromagnetic region (i.e. for x = 0.0 to 0.4). Furthermore, an extraordinarily large negative thermal expansion at low temperatures and a large forced volume magnetostriction at 4.2 K have been observed in the ferromagnetic compound with x = 0.4, both of which are comparable in magnitude to those observed in Fe-Ni Invar alloys. Fairly large forced volume magnetostriction, which does not vary linearly with the applied field, has been observed in mictomagnetic compounds with x = 0.5 and 0.6. This phenomenon has been explained by use of a simple model in which the volume change is ascribed to the change in the polarisation of the 3d band. (author)

[en] Magnetic and Moessbauer measurements have been made for the pseudobinary Zr(Fesub(1-x)Cosub(x))₂ system. Both measurements clearly show that mictomagnetism appears for x=0.5 approximately 0.7, as ferromagnetism vanishes

[en] We analyze the three-dimensional axial next-nearest-neighbor Ising model composed of two kinds of alternately stacked ferromagnetic layers with different intralayer interactions by using Monte Carlo (MC) simulation. The detailed analyses of the magnetization and the spin correlations perpendicular to the stacked direction, assure and clarify the existence and the nature of the paramagnetic layers in some modulated phases with wave numbers, 1/4, 1/8, 3/16. This is the first MC confirmation of the partially disordered states which have been predicted by previous molecular field calculation and/or observed in materials such as CsCoCl₃, CuFeO₂ and CeSb

[en] We consider an extended 3-d axial next-nearest-neighbor Ising model, which is composed of two kinds of alternately stacked ferromagnetic layers with different intralayer interactions. Monte Carlo simulation is performed on L³ simple cubic lattice (L=20-80). Since a minimum of the fourth-order energy cumulant(V_L), which corresponds to phase transition to partially disordered phase, reaches the value very close to ((2)/(3)) as L→∞, we conclude that this phase transition is second order. From the finite-size scaling analysis of V_L and specific heat, we estimate the critical exponents

[en] A systematic study of extraction of pertechnetate with tetraphenylarsonium chloride (TPAC) in chloroform from aqueous chloride solutions has been carried out at 25 deg C at ionic strength of 1.0. Fundamental parameters governing the distribution equilibrium of TPAC were determined. Extraction behavior of pertechnetate was established on the basis of the distribution mechanism of TPAC. (author) 12 refs,; 5 figs

[en] The magnetic phase diagrams of S=((1)/(2)) axial third-nearest-neighbour Ising (A3NNI) model under an external field have been studied by means of the molecular field approximation. The phase boundaries among paramagnetic, (anti)ferromagnetic and various modulated phases are determined by analysing the frequency-dependent susceptibility, or by solving the coupled equations for magnetisations for spins up to 17, iteratively. The resultant phase diagram is found to be very consistent with the exact results for the ground state spin ordering and to be far improved than existing finite temperature phase diagrams for the same model

[en] Small-angle total and inelastic neutron scattering measurements were performed on a single crystal of the ordered alloy Fe/sub 0.7/Al/sub 0.3/. The behavior of the Q dependence of the small-angle intensity can be classified into four temperature regions which correspond to the bulk behavior: (i) T>T/sub c/ = 510 K (paramagnetic region); the line shape is Lorentzian with kappa→0 as T>T/sub c/. (ii) 300 K< T< T/sub c/ (ferromagnetic region); I(Q)approx.Q^-2 as expected from spin waves. (iii) 100 K< T<300 K (near T/sub c//sup inv/); I(Q)approx.Q/sup -alpha/, with α being T dependent and reaching a maximum value α = 2.6. In this region the T dependence of the intensity exhibits a peak which is Q dependent. Near T/sub c//sup inv/roughly-equal160 K, a thermal hysteresis and novel time dependence of the scattering is observed. (iv) T<100 K (spin-glass regime); the line shape is again Lorentzian with kappa increasing with decreasing T. No anomaly is observed at T/sub f/roughly-equal90 K. The inelastic measurements reveal that spin waves exist in the ferromagnetic regime but disappear as the temperature is lowered. For temperatures less than T/sub c//sup inv/, an elastic central peak appears which increases as T is decreased. The results are interpreted in terms of random-field effects

[en] An attempt is made to investigate the quantitative relationship between VLF phase deviations in SPA (sudden phase anomalies) events and associated solar X-ray fluxes in the 1 to 8 A band during solar flares. The phase deviations (Δphi) of the 18.6 kHz VLF wave transmitted from NLK, USA are used in this analysis which were recorded at Nishinomiya, Japan during the period June 1974 to May 1975. The solar X-ray fluxes (F₀) in the 1 to 8 A band are estimated from fsub(min) variations using the empirical expression given by Sato (J.Geomag.Geoelectr.;27: 95(1975)), because no observed data were available on the 1 to 8 a X-ray fluxes during the period of the VLF observation. The result shows that the normalized phase variation, Δphi/coschisub(min), where chisub(min) represents the minimum solar zenith angle on the VLF propagation path, increases with increasing logF₀. A theoretical explanation for this is presented assuming that enhanced ionizations produced in the lower ionosphere by a monochromatic solar X-ray emission are responsible for the VLF phase deviations. Also it is found that a threshold X-ray flux to produce a detectable SPA effect is approximately 1.5 x 10^-3 cm^-2 sec^-1 in the 1 to 8 a band. (author)

[en] The crystal structures, magnetic properties, and ⁵⁷Fe Moessbauer effects are studied on the A(Fesub(1-x)Bsub(x))₂ (A = Y or Zr, B = Al or Ni) Laves phase intermetallic compounds over the concentration range from x = 0 to 0.4. The substitution of Al for Fe rapidly reduces the Fe magnetic moment in both the Y and Zr systems. In the Y system, beyond the concentration where the ferromagnetic ordering vanishes, the Fe moments are still retained and couple antiferromagnetically or form a spin glass. The substitution of Ni for Fe causes no remarkable change in the Fe magnetic moment in the Y system, but it reduces the Fe moment in the Zr system. (author)

[en] Magnetization, Moessbauer effect, and thermal expansion are measured on the pseudobinary (Zr/sub 1-x/Ta/sub x/)Fe₂ Laves phase intermetallic compounds. With increasing x, the crystal structure changes from C15 to C14 around x=0.3 to 0.4. Ferromagnetism is observed for the C15 phase and antiferromagnetism for the C14 phase, where the spin structure is considered to be the same as that of TiFe₂. An Invar like large thermal expansion anomaly is observed, most prominently for x=0.2. A strong magnetovolume coupling is found in the antiferromagnetic C14 phase as well as in the ferromagnetic C15 phase. (author)