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The equilibrium structure of [100] oriented steps on the (100) surface of a simple cubic crystal has been examined by Monte Carlo simulation methods. The structures of four surfaces (20,1,0), (10,1,0), (5,1,0) and (100), were simulated and the results combined to determine the properties of an isolated step. The step edge (ledge) energy/length first increases with temperature and then decreases continuously until, at a temperature TR, it vanishes. This temperature, TR, corresponds to the critical temperature for surface roughening, at which the structural and thermodynamic properties of the stepless surface exhibit singularities. These results indicate that TR may be regarded as the temperature above which surface steps may form without increasing the surface free energy. Alternatively, these results show that TR also corresponds to the temperature above which the cusp in a polar plot of surface free energy disappears and the surface becomes nonsingular. e/kTR as determined in this simulation is ∼ 1.57, where e is the strength of the first neighbor bond.

A pair approximation method is described for the interface kinetics of a simple cubic (100) surface with no surface migration. Condensation and evaporation are considered explicitly in a system of master equations applied to a pair of sites; and the effect of the neighboring sites is treated with a set of parameters which are determined self-consistently. Runge Kutta numerical integration of the equations yields the time evolution of the surface. The results for a high entropy of transformation indicate a region of metastable states (zero growth rate) for small driving force, and the instantaneous growth rate is a periodic function of time for larger driving force. The period of the variations is the time required to grow a monolayer, and the amplitude is less than that obtained by Temkin using the mean field approximation. The variations appear as artifacts of most approcimation methods which treat a limited number of sites. The average growth rate is less than the limiting Wilson-Frenkel law for all growth conditions studied. This results since the surface becomes quite rough in the presence of a large condensation rate, and therefore its evaporation rate is greater than the evaporation rate of an equilibrium surface assumed in the Frenkel model. The metastable region is absent at low entropies of transformation and here the growth rate is nearly linear in the driving force. Agreement with Monte Carlo data is excellent for a low entropy of transformation and for all materials at high growth rates.

The structure of the (110) crystal-vapor or crystal-melt interface of an fcc crystal has been calculated in zeroth order approximation. The results indicate that structural roughening of the interface occurs in the range 0.03 kT / L kT / L . Here L is the enthalpy of vaporization or melting and T is the absolute temperature. The relative population of surface energy levels has also been computed. For kT / L > 0.3, the surface approximates an ideally rough configuration. The surface self diffusion coefficient has been computed from the theoretical distribution of atoms at the interface. The results indicate a positive departure from Arrhenius behavior in the temperature interval where roughening occurs. In the L / kT range encountered in metal-vapor systems the theoretically obtained log ( D s versus L / kT relationship is linear. The departure from linearity commonly observed in fcc metal-vapor system is therefore not predicted to be the result of structural roughening of the (110) orientation surface.

This letter contains some calculations of the thermodynamic properties of lattice model interfaces. The work is compared with that reported recently by Hunt and Gale (see abstr. A16653 of 1974). Their results are shown to be greatly influenced by their restrictive limitation of the interface width.

The (100), simple-cubic, lattice-gas interface structure has been simulated by Monte Carlo methods. For the interface width $L$ we find $L=(1.05\ifmmode\pm\else\textpm\fi{}0.04){(1\ensuremath{-}\frac{T}{{T}_{c}})}^{\ensuremath{-}0.69}$, in the range $T\ensuremath{\gtrsim}0.5{T}_{c}$. This is larger than the bulk correlation length $\ensuremath{\xi}$ by a factor of \ensuremath{\sim} 3.

We have studied the interface between regions of opposite spin in the simple cubic Ising model. Low-temperature expansions of moments of the gradient of the density profile and of the slope at its midpoint suggest that the interface width diverges at a temperature ${T}_{R}$ about half the critical temperature. We discuss the physical significance of this transition and implications for general theories of interfacial properties.

Magnetic properties of metallic glasses in the system (Fe‐Co‐Ni) 0.75 (P‐B‐Al)0.25 have been investigated. Samples were made by the roller quenching technique in the form of ribbons 0.002 in. thick and about 0.125 in. wide. Room temperature saturation magnetization, 4πMs, ranged from a high value of 13,500 Gauss for Fe0.75P0.06Al0.03 to essentially zero for Ni0.75P0.16B0.06Al0.03 which exhibits only weak temperature independent paramagnetism. The highest Curie temperatures occurred in mixed Fe‐Co alloys with a high value of 715°K for (Fe0.4Co0.6)0.75 P0.16B0.06Al0.03. The sign of the magnetostriction was found to change from positive for Fe rich alloys to negative for Co rich alloys so that low or zero magnetostriction composition can be made near the Co rich side of the pseudo‐ternary phase field. For example (Fe0.04Co0.96)0.75P0.16B0.06 Al0.03 has nearly zero magnetostriction. This alloy responds to heat treatment in a magnetic field, developing properties which compare favorably with commercial superma...

We have recently examined the microscopic electrical inhomogeneities present in dislocation free, floating zone, Si crystals grown under various conditions by conductivity mode scanning electron microscopy. Schottky barriers produced by evaporation of thin Au-Pd (on N type) or Ti (on P type) electrodes were employed in order to eliminate possible changes in defect structure or electrical activity during production of a diffused junction.Doped and undoped crystals, as well as crystals subjected to special treatments, such as melt quenching were examined in this study. Prior to SEM analysis, each crystal was characterized by preferential etching, Cu or Li decoration, and x-ray topography. All of the defects detected by these methods, save C impurity striations detected via their dilatation of the Si lattice in x-ray topographs, were observed in the SEM experiments. For example, “swirl” defects of both type “A” (large) and type “B” (small) were readily revealed via the enhanced recombination rate of electron beam injected carriers in their vicinity (see Figs. 1 and 2).

The formation of glassy (amorphous) metallic alloys by rapid quenching from the liquid state was discovered in 1960 (1), and subsequent work revealed that certain metallic glasses are ferromagnetic (2). Recently, transition metal based alloys, which possess Curie temperatures as high as 700°K and saturation magnetizations up to 15,000 Gauss, have been shown to be both mechanically very hard and magnetically quite soft (3). We have applied the SEM technique of Fathers et al. (4) as well as electron transmission Lorentz microscopy to a study of roller quenched (5) metallic glass ribbons of composition: TM0.75P.16X.06A1.03, where TM denotes Fe, Co, Ni, or an alloy of these and X denotes either B, C or Si (6).

We have applied the scanning electron microscopy (SEM) technique of Fathers et al. to a study of domain structure in metallic glasses of the form TM0.75P0.16X0.06Al0.03, where TM denotes Fe, Co, Ni, or an alloy of these and X denotes either B, C, or Si. The domain structure is dominated by the presence of a spatially nonuniform uniaxial anisotropy which is related to the flow processes induced by quenching the molten alloy. The existence of both a magnetostrictive and a directional ordering source of anisotropy is indicated.

The magnetic properties of zero magnetostrictive metallic glass have been investigated using both standard fluxmeter methods and domain patterns obtained from a scanning electron microscope technique. This investigation shows that the material is not magnetically isotropic but rather has preferred directions of magnetization that are determined by the details of the quenching process. The magnetic aniostropy produced by subsequent field anneal dominates the original anisotropy and determines the magnetic behavior after the heat treatment.