# Showing papers in "Journal of Applied Physics in 1962"

••

[...]

TL;DR: In this paper, a unified treatment of the mechanics of deformation and acoustic propagation in porous media is presented, and some new results and generalizations are derived, including anisotropic media, solid dissipation, and other relaxation effects.

Abstract: A unified treatment of the mechanics of deformation and acoustic propagation in porous media is presented, and some new results and generalizations are derived. The writer's earlier theory of deformation of porous media derived from general principles of nonequilibrium thermodynamics is applied. The fluid‐solid medium is treated as a complex physical‐chemical system with resultant relaxation and viscoelastic properties of a very general nature. Specific relaxation models are discussed, and the general applicability of a correspondence principle is further emphasized. The theory of acoustic propagation is extended to include anisotropic media, solid dissipation, and other relaxation effects. Some typical examples of sources of dissipation other than fluid viscosity are considered.

3,158 citations

••

[...]

TL;DR: In this article, the authors established and applied variational theorems for the derivation of bounds for the effective magnetic permeability of macroscopically homogeneous and isotropic multiphase materials.

Abstract: Variational theorems are established and applied to the derivation of bounds for the effective magnetic permeability of macroscopically homogeneous and isotropic multiphase materials. For reasons of mathematical analogy the results are also valid for the dielectric constant, electric conductivity, heat conductivity, and diffusivity of such materials. For the case of two‐phase materials, the bounds derived are the most restrictive ones that can be given in terms of the phase permeabilities and volume fractions. Comparison of present theoretical results with existing experimental data shows good agreement.

2,636 citations

••

[...]

TL;DR: In this article, the acceptor electrode can form ohmic contact for hole injection into these crystals and that space-charge-limited currents can be drawn through them, which strongly indicates that the acceptors electrode can strongly indicate that the hole mobility in p−terphenyl is about 3×10−2 cm2/v sec, is independent of the field at least up to about 4×104 v/cm, and the hole trap concentration is at least 1013 cm−3.

Abstract: Electrical conductivity measurements were performed with thin (50 μ) single crystals of p‐terphenyl, p‐quaterphenyl, and anthracene supplied with aqueous electrodes, one of which was an iodine‐iodide solution (acceptor electrode), and the other an iodide solution. The results strongly indicate that the acceptor electrode can form ohmic contact for hole injection into these crystals and that space‐charge‐limited currents can be drawn through them. The crystals were found to contain hole‐trapping states the location‐in‐energy of which can be approximated by a decreasing exponential distribution above the valence band. The measurements showed that the hole mobility in p‐terphenyl is about 3×10−2 cm2/v sec, is independent of the field at least up to about 4×104 v/cm, and that the hole‐trap concentration is at least 1013 cm−3. The acceptor electrode used does not form ohmic contact to crystals of naphthalene and diphenyl; an explanation for this is proposed. Some theoretical aspects of ohmic contact formation ...

780 citations

••

[...]

TL;DR: In this paper, the authors investigated the electrical conduction mechanism in the film plane of ultrathin, evaporated metal films and showed that the conductivity depends exponentially on reciprocal temperature, and it should be independent of field at low fields.

Abstract: The electrical conduction mechanism in the film plane of ultrathin, evaporated metal films was investigated. These films consist of a planar array of many small discrete islands. The conduction process consists of, first, charge carrier creation which is thermally activated and involves charge transfer between initially neutral particles, and, second, the drift velocity of these charges in an applied field. Charge transfer between particles occurs by tunneling. The following features were predicted and can be verified experimentally: the conductivity depends exponentially on reciprocal temperature, and it should be independent of field at low fields. Deviations from the exponential temperature dependence can be understood in terms of a spectrum of activation energies, while deviations from Ohm's law at high fields can be explained readily in terms of a field dependent activation energy.

685 citations

••

[...]

TL;DR: In this paper, the authors derived an analytic expression for the time spent by a particle tunneling through a potential barrier with constant average velocity, and showed that the resultant transmission time is positive, nonzero and in principle measurable.

Abstract: Analytic expressions are given for the time spent by a particle tunneling through a potential barrier. The expressions are derived for an incident wave packet which is initially Gaussian, centered about a point an arbitrary distance away from a rectangular potential barrier and moving toward the barrier with constant average velocity. Upon collision with the barrier, the packet splits into a transmitted and a reflected packet. The resultant transmission time is positive, nonzero and in principle measurable. Although the transmission time becomes quite large as the incident kinetic energy becomes very small, in general, for nonzero incident momentum and finite potential barriers which are neither very thick nor very thin, the transmission times are less than the time that would be required for the incident particle to travel a distance equal to the barrier thickness. The transmission times for metal‐insulator‐metal thin film sandwiches, given approximately by δt3=ℏ/(Efφ)12, where Ef is the Fermi energy of ...

653 citations

••

[...]

General Electric

^{1}TL;DR: Exchange anisotropy describes a magnetic interaction across the interface between two magnetic materials as discussed by the authors, and it has been found to exist between ferro-antiferromagnetic materials, ferri−antiferrous materials, and ferri-ferromagnetic material.

Abstract: Exchange anisotropy describes a magnetic interaction across the interface between two magnetic materials. A shifted hysteresis loop, sinθ torque curve, and rotational hysteresis in magnetic fields greater than 2K / Ms may result from this interaction if one of the materials is antiferromagnetic. This interaction has been found to exist between ferro‐antiferromagnetic materials, ferri‐antiferromagnetic materials, and ferri‐ferromagnetic materials. The work of various people is discussed in terms of the expected behavior in these exchange coupled systems. Some interesting results of the exchange interaction are reviewed. These include improved properties of fine particle magnets, a memory effect in a mixed ferrimagnetic spinel, a rotatable anisotropy in thin films, and an explanation for the reverse magnetization of a deposit in the earth's crust. The interfacial conditions necessary to obtain the interaction between the two magnetic systems are discussed, and it is shown that they are met in several cases. Models are presented which yield rotational hysteresis in magnetic fields greater than 2K / Ms as has been found in all of the exchange coupled systems.

596 citations

••

[...]

TL;DR: In this paper, the voltage for maximum current is independent of film thickness for films between 150 and 1000 A/cm2, and peak-to-valley ratios of 30:1 and current densities of 10 A/m2 are typical.

Abstract: Negative resistance and large current densities have been observed in the direct‐current—voltage characteristics of five metal‐oxide‐metal sandwiches prepared from evaporated metal films. The systems studied and their voltages for maximum current are: Al‐SiO‐Au, 3.1 V; Al‐Al2O3‐Au, 2.9 V; Ta‐Ta2O5‐Au, 2.2 V; Zr‐ZrO2‐Au, 2.1 V; and Ti‐TiO2‐Au, 1.7 V. For aluminum oxide, which has been most extensively studied, the voltage for maximum current is independent of film thickness for films between 150 and 1000 A thick; the phenomenon is not field dependent. Peak‐to‐valley ratios of 30:1 and current densities of 10 A/cm2 are typical. Maximum current densities at peak voltage are 25 A/cm2; minimum current densities are 0.01 A/cm2. Switching time from peak current to valley current is <0.5 μsec but negative resistance is not found for 60‐cycle voltages. Establishment of the dc characteristics and dependence on temperature and atmosphere are described. Electron emission from aluminum oxide sandwiches can occur at 2.5 V. Space‐charge‐limited currents in the insulator provide a possible mechanism for the current‐voltage curves and large currents below the voltage for maximum current through the oxide films. The mechanism responsible for negative resistance is uncertain.

586 citations

••

[...]

TL;DR: In this article, high explosive driving systems and high speed optical techniques have been used to investigate the compressional behavior of xcut, ycut, and zcut quartz crystals and fused quartz up to about 750 kbar pressure.

Abstract: High explosive driving systems and high‐speed optical techniques have been used to investigate the compressional behavior of x‐cut, y‐cut, and z‐cut quartz crystals and fused quartz up to about 750 kbar pressure. In both forms of silica two‐wave structures over a wide pressure range are identified as resulting from unusually high Hugoniot elastic limits. In crystalline quartz a dependence of the pressure of these elastic limits on driving shock pressure and sample thickness is associated with a relaxation‐time phenomenon connected with the transition from elastic to fluid‐like flow. Recovery experiments are reported which confirm a previous observation that sufficiently high shock pressures result in the transition of crystalline quartz to the fused state, and the implications of the compression data in this regard are discussed. Observations on fused quartz deomonstrate that shock‐wave loading results in both the anomalous compression at low pressures and the compaction phenomena above 100 kbar which have been reported from hydrostatic experiments.

580 citations

••

[...]

TL;DR: In this paper, the authors show that for properly prepared material, significant amplification is expected up to the microwave frequencies, and at high frequencies, gain is reduced because electron diffusion smooths out the electron bunching necessary for amplification.

Abstract: An ultrasonic wave traveling in certain directions in a piezoelectric semiconductor such as cadmium sulfide can be amplified or attenuated by application of a dc electric field. The direct current flowing through the medium in the presence of an ultrasonic wave creates a traveling ac field which interacts with the ultrasonic wave. Amplification occurs when the drift velocity of the electrons exceeds the velocity of sound. For strongly piezoelectric semiconductors, amplification of as much as several percent per wavelength of path is obtainable. Calculations show that for properly prepared material, significant amplification is expected up to the microwave frequencies. At high frequencies, gain is reduced because electron diffusion smooths out the electron bunching necessary for amplification. The dc power required increases rapidly with frequency, and at frequencies above one or two thousand megacycles only pulsed operation seems feasible. Applications as a tool in ultrasonic studies, and for devices such as delay lines and amplifiers, are also discussed.

548 citations

••

[...]

TL;DR: In this paper, a plane elastic wave propagating in a piezoelectric crystal may be accompanied by longitudinal electric fields which provide an additional elastic stiffness when the crystal is also semiconducting, these fields produce currents and space charge resulting in acoustic dispersion and loss.

Abstract: A plane elastic wave propagating in a piezoelectric crystal may be accompanied by longitudinal electric fields which provide an additional elastic stiffness When the crystal is also semiconducting, these fields produce currents and space charge resulting in acoustic dispersion and loss A linear theory of this effect is developed, taking into account drift, diffusion, and trapping of carriers for both extrinsic and intrinsic semiconductors Conductivity modulation sets an upper limit on strain amplitude for a linear theory The directional characteristics and the magnitude of the effects are illustrated for CdS and GaAs The Appendix treats the interaction of an arbitrary acoustic plane wave with the electromagnetic fields in a piezoelectric crystal (based on a treatment by Kyame [J J Kyame, J Acoust Soc Am 21, 159 (1949); 26, 990 (1954)]) and further shows explicitly that only the effects of longitudinal electric fields need be considered

496 citations

••

[...]

TL;DR: In this article, an analysis for the absorption corrections necessary for the x-ray analysis of diffraction data from a liquid sample confined within a cylindrical sample cell is presented, and the evaluation of necessary absorption integrals has been formulated in a numerical calculus procedure appropriate for a digital computer.

Abstract: An analysis is presented for the absorption corrections necessary for the x‐ray analysis of diffraction data from a liquid sample confined within a cylindrical sample cell. The evaluation of necessary absorption integrals has been formulated in a numerical calculus procedure appropriate for a digital computer. The procedure has been verified against previous graphical computations.

••

[...]

TL;DR: In this paper, the diffusion coefficients of Al26 and Mn54 in aluminum have been determined between 450° and 650°C. The exact solution to Fick's second law for the appropriate boundary conditions was used in treating the data.

Abstract: Diffusion coefficients of Al26 and Mn54 in aluminum have been determined between 450° and 650°C. Low specific activities of the isotopes necessitated use of a thick layer technique. The exact solution to Fick's second law for the appropriate boundary conditions was used in treating the data. Temperature dependence of the diffusion coefficients may be expressed by the following equations: DAl26=1.71 exp−(34 000/RT)DMn54=0.22 exp−(28 800/RT).

••

[...]

TL;DR: In this paper, the dependence of space-charge-limited currents on applied electric field in insulators is investigated. But the results indicate that gross errors in trap depth and density can be made if it is simply assumed that the rapid rise in current toward the trap-free curve with increasing applied voltage always occurs when the traps are filled.

Abstract: Trap depths and densities can be determined from the analysis of the dependence of space‐charge‐limited currents on applied electric field in insulators. Values obtained from space‐charge‐limited current measurements are compared with those obtained from thermally stimulated currents and from photocurrent decay on the same crystal of cadmium sulfide. The results indicate that gross errors in trap depth and density can be made if it is simply assumed that the rapid rise in current toward the trap‐free curve with increasing applied voltage always occurs when the traps are filled. Although this may sometimes be true, it is also possible for such a rapid rise to result from field ionization of the traps, or even in certain cases from the onset of double injection. Even if the latter effects occur, however, proper analysis of the space‐charge‐limited current data permits an evaluation of trap depth and density which is completely consistent with independent measurements of thermally stimulated current and photocurrent decay.

••

[...]

TL;DR: Sputtering yields of various metals have been determined for He+−, Kr+•, and Xe+−ion bombardment in the energy range 100 to 600 ev as mentioned in this paper, showing a periodic dependence on atomic number similar to that of the reciprocals of the heats of sublimation.

Abstract: Sputtering yields of various metals have been determined for He+‐, Kr+‐, and Xe+‐ion bombardment in the energy range 100 to 600 ev. Yields at 400 ev show a periodic dependence on atomic number similar to that of the reciprocals of the heats of sublimation.

••

[...]

TL;DR: In this article, the authors obtained stress-strain curves and transient creep curves for single crystals from calculations based on the observed behavior of dislocations in LiF, and the strain rate equation, e=bnv.

Abstract: Stress‐strain curves and transient creep curves for single crystals are obtained from calculations based on the observed behavior of dislocations in LiF, and the strain rate equation, e=bnv. The pronounced yield drops and apparent ``delay times'' predicted by the calculations are observed experimentally. This agreement between calculation and experiment implies that further consideration of the calculations may give some insight into the yield point and transient creep behavior of single crystals. Several parameters are varied in the calculation in order to determine the effect of such things as testing machine speed, machine hardness, rate of dislocation multiplication, work‐hardening rate, number of mobile dislocations initially present, and the dependence of dislocation velocity on stress. The parameter that most strongly influences the yield points and transient creep behavior of a given material is n0, the number of mobile dislocations initially present. The wide range of observed yield point and tr...

••

[...]

TL;DR: A functional relationship between dielectric constant and voltage for a ferroelectric in the paraelectric state is derived, and Fourier capacitance coefficients for different applied voltage functions are computed.

Abstract: A functional relationship between dielectric constant and voltage for a ferroelectric in the paraelectric state is derived, and Fourier capacitance coefficients for different applied voltage functions are computed. It is shown that because the loss tangent of a ferroelectric in the paraelectric state is proportional to frequency, it can be represented in the same way as a varactor; i.e., as a series resistance and capacitance. It is concluded that since the power‐handling capability of single‐crystalline ferroelectric is virtually unlimited, and since in many cases it has lower loss than a varactor diode, it will soon find wide application in parametric device design.

••

[...]

TL;DR: In this paper, a theory for impurity-controlled dislocation mobility and the resultant temperature variation of the flow stress of lithium fluoride is derived for tetragonal lattice distortions such as result from the introduction of magnesium into lithium fluoride.

Abstract: A theory is derived for impurity‐controlled dislocation mobility and the resultant temperature variation of the flow stress of lithium fluoride. The theory is suitable to crystals in which the hardening is primarily due to tetragonal lattice distortions such as result from the introduction of magnesium into lithium fluoride, these being defects whose interactions with dislocations have been calculated previously. Dislocation motion is envisioned as a series of thermally activated dislocation jumps through the stress fields produced by individual solute atoms. The theory predicts the observed temperature variation of the flow stress within 25%, approximate values of the slopes of the velocity‐stress relations, and the activation energy for dislocation motion.

••

[...]

General Electric

^{1}TL;DR: Magnetization and electrical resistivity measurements on an iron-rhodium alloy of approximate composition FeRh, having CsCl-type structure, confirm recent x-ray and neutron diffraction evidence for a first-order antiferromagnetic-ferromagnetic transition at about 350°K as discussed by the authors.

Abstract: Magnetization and electrical resistivity measurements on an iron-rhodium alloy of approximate composition FeRh, having CsCl-type structure, confirm recent x-ray and neutron diffraction evidence for a first-order antiferromagnetic-ferromagnetic transition at about 350°K. From 350°K down to 77°K, an essentially constant, field-independent susceptiblity of about 1×10−4 emu/g is observed. Above 350°K, the alloy behaves like a normal ferromagnet with a Curie point of 675 °K and a saturation magnetization (extrapolated to 0°K) of 130 emu/g. This σ0 value is equivalent to an average atomic moment of 1.85 μb, or to 3.85 μb per iron atom if the rhodium moment is assumed to be zero. Alternatively, if the iron moment is taken to be 2.2 μb, the rhodium moment has to be about 1.5 μb. Qualitative results are given for the effect of high magnetic fields and pressures on the first-order transition temperature of this alloy.

••

[...]

TL;DR: In this article, the possibility of the rotation of a subgrain with respect to its neighbors as a natural process during recrystallization is analyzed thermodynamically and kinetically.

Abstract: The possibility of the rotation of a subgrain with respect to its neighbors as a natural process during recrystallization is analyzed thermodynamically and kinetically. It is found that it is energetically possible if the direction of rotation favors the elimination of low‐angle boundaries over that of high‐angle boundaries, the elimination of twist and asymmetric boundaries over that of the tilt and symmetric boundaries, and the elimination of the large‐area boundaries over that of the small‐area boundaries. Since the rotation direction has two degrees of freedom, there exists a relation between the two degrees of freedom such that directions whose two degrees of freedom fulfill such a relation provide no driving force for rotation. All other directions will supply free energy to rotate in one sense or the opposite. Kinetically one of the following two processes within one boundary can be rate‐controlling: the cooperative movement of dislocations in the boundary, and the cooperative diffusion of vacancies in the lattice. The rotation of a subgrain favors the elimination of one of the boundaries which contributes the largest fraction of driving force and also the largest fraction of resistance. This causes the subgrain to coalesce with the other subgrain separated by this boundary. The estimated time required for one such coalescence compares favorably with the observed rate of subgrain growth in Al.

••

[...]

TL;DR: In this article, the authors presented an analysis of the field variation of Townsend's first ionization coefficient and ion mobilities, and the length of the dark space has been obtained from the calculated distribution of light output across the gap and agrees with the cathode-fall distance calculated from the field distribution.

Abstract: Calculations of the variation of cathode‐fall voltage, the cathode‐fall distance, and the Aston dark space with current density have been made for the rare gases and a few molecular gases on an electronic computer. The calculations were based upon Townsend's ionization equations, but included the field distortion due to space charge. New analyses of the field variation of Townsend's first ionization coefficient and ion mobilities are presented. The length of the dark space has been obtained from the calculated distribution of light output across the gap and agrees with the cathode‐fall distance calculated from the field distribution. Comparisons of the calculated cathode‐fall characteristics with published experimental results indicate the probable validity of the model used for the calculations.

••

[...]

TL;DR: The properties of a pressure transducer consisting of a single-crystal silicon diaphragm having stress-sensitive piezoresistive regions formed by localized diffusion of impurities have been theoretically and experimentally investigated as mentioned in this paper.

Abstract: The properties of a pressure transducer consisting of a single-crystal silicon diaphragm having stress-sensitive piezoresistive regions formed by the localized diffusion of impurities have been theoretically and experimentally investigated. The longitudinal and transverse piezoresistance effects are discussed and the results are applied to the stress pattern of a deformed diaphragm. The conditions under which the stress in the diaphragm varies linearly with applied pressure are discussed and good agreement between the predicted and measured sensitivity is found in both the linear and nonlinear cases.

••

[...]

HRL Laboratories

^{1}TL;DR: Giant pulses of optical maser radiation have been produced by varying the effective reflectivity of the reflecting surfaces at the ends of the ruby rod through a Kerrcell switching technique as discussed by the authors.

Abstract: Giant pulses of optical maser radiation have been produced which are several orders of magnitude larger than the commonly observed spontaneous pulses. The pulses were produced by varying the effective reflectivity of the reflecting surfaces at the ends of the ruby rod through a Kerr‐cell switching technique. The measured pulse characteristics are found to be in agreement with theoretical predictions.

••

[...]

TL;DR: In this paper, the spectroscopic method has been used to study sputtering yields under normally incident ion bombardment at very low ion energies, and data have been extrapolated to determine threshold energies for sputtering under normal incidence.

Abstract: The spectroscopic method has been used to study sputtering yields under normally incident ion bombardment at very low ion energies. Data have been extrapolated to determine threshold energies for sputtering under normal incidence. These estimated thresholds are approximately the same energy (roughly four times the heat of sublimation) as the displacement thresholds for radiation damage. The mass ratio between ion and target atoms plays hardly any role in the thresholds.

••

[...]

TL;DR: In this article, low voltage electron diffraction and pumping speed measurements have been used to study the reactions of oxygen with clean Si (111) and (100) surfaces in the temperature range between 600° and 1000°C and the oxygen pressure range between 7×10−9 and 1 ×10−4 mm Hg.

Abstract: Low voltage electron diffraction and pumping speed measurements have been used to study the reactions of oxygen with clean Si (111) and (100) surfaces in the temperature range between 600° and 1000°C and the oxygen pressure range between 7×10−9 and 1×10−4 mm Hg. The results support the contention that a wide region in which Si is atomically clean exists in this range. Measurements of steady states yield an activation energy of about 90 kcal/mol for the clean‐up process. The results also suggest a practical method for producing pure coatings of SiO2 by a technique similar to, but with several advantages over, the familiar Si+SiO2 reaction process.

••

[...]

TL;DR: The Hall mobility in semiconductors and insulators can be greatly affected by inhomogeneous impurity distributions due to the formation of large space-charge regions surrounding local inhomogeneities.

Abstract: The Hall mobility in semiconductors and insulators can be greatly affected by inhomogeneous impurity distributions. This is due to the formation of large space‐charge regions surrounding local inhomogeneities. The scattering cross section of Coulombic centers can be increased by over an order of magnitude when inhomogeneously distributed. The mobility resulting from scattering from inhomogeneities varies roughly as T−½ and decreases with decreasing carrier concentration. Assuming that inhomogeneities can occur frequently, various anomalous Hall mobility effects can be explained, such as mobility ``killers'' in GaAs, InAs, and InP; giant scattering cross sections in GaAs, InP, CdS, and CdSe; abnormally low mobilities in compensated InAs; and low mobilities in ZnO containing precipitates.

••

[...]

TL;DR: The thermoelectric figure of merit (z), resistivity, and Seebeck coefficient have been measured between 20° and 300°K on single crystals of several alloys in the range from 1% to 40% antimony in bismuth.

Abstract: The thermoelectric figure of merit (z), resistivity, and Seebeck coefficient have been measured between 20° and 300°K on single crystals of several alloys in the range from 1% to 40% antimony in bismuth. These materials are semimetals (0 to 5% antimony) or small energy gap intrinsic semiconductors (5 to 40% antimony) and all are n type. The Seebeck coefficients and figures of merit are anisotropic, the larger values being those measured parallel to the threefold symmetry axis. In the 12% antimony alloy the larger z rises from 1.0×10−3/°K at 300°K to a maximum of 5.2×10−3/°K at 80°K and falls rapidly at lower temperatures. All of the alloys between 3% and 16% antimony have a maximum z near 5×10−3/°K at a temperature between 70°K and 100°K. The 5% antimony alloy has the highest z at room temperature (z=1.8×10−3/°K). In this material, the Seebeck coefficient is practically constant (S=−110±10 μv/°K) between 77° and 300°K and the ratio of the thermal to electrical conductivities is close to the theoretical Wi...

••

[...]

TL;DR: In this article, a study of the effect of etching on particle tracks in various silicate minerals is reported as a function of the etching reagent, etching temperature, and etching time.

Abstract: When a heavy charged particle such as a fission fragment traverses certain materials it leaves a trail of radiation damage which shows up as a track when a sample is viewed by transmission electron microscopy. If a sample of a silicate mineral containing such tracks is immersed in a suitable reagent such as hydrofluoric acid it has been found that the tracks are very selectively attacked. Fine hollow channels are formed along the particle paths while the rest of the material is untouched. A study of this effect in various silicate minerals is reported as a function of etching reagent, etching temperature, and etching time. The minimum width of the etched channels is considerably less than the apparent widths of the tracks prior to etching. It is concluded that the track images result in large part from elastic strains surrounding a damaged core. The etching effect also serves to ``develop'' and ``fix'' particle tracks and hence increases the usefulness of silicate minerals as particle detectors.

••

[...]

TL;DR: In this article, the problem of electromagnetic wave propagation along a dielectric cylinder of elliptical cross section is considered, and two infinite determinants representing the characteristic equations for the two types of hybrid waves (the eHEmn, and the 0HEmns) are derived.

Abstract: The problem of electromagnetic wave propagation along a dielectric cylinder of elliptical cross section is considered. Two infinite determinants representing the characteristic equations for the two types of hybrid waves (the eHEmn, and the 0HEmn waves) are derived. It is found that there exists two dominant waves which possess zero cutoff frequencies. The characteristic roots of these two dominant waves are computed for various values of eccentricity and relative dielectric constant. Theoretical propagation constants for the dominant waves are verified by experiments.

••

[...]

TL;DR: In this article, the geometric structure factor for x-ray scattering was found different in opposite directions along the polar axis, and the two types of surfaces perpendicular to the polar axes were identified.

Abstract: Crystallographic polarity associated with the zinc‐blende and the wurtzite structures has been studied in the following II‐VI sulfides, selenides and tellurides; ZnS, ZnTe, CdS, CdSe, CdTe, HgSe, and HgTe. The CdS and CdSe have the wurtzite structure and the others the zinc‐blende structure. Consistent with theoretical calculations, the geometric structure factor for x‐ray scattering was found different in opposite directions along the polar axis. Consequently, the two types of surfaces perpendicular to the polar axis were identified. The etching behavior of these surfaces was correlated with the x‐ray results so that simple etching tests were developed for the identification of the {111} (zinc blende) or the {00.1} (wurtzite) surfaces.

••

[...]

TL;DR: In this article, it is shown that a large part of the correlation error can be removed by permitting different orbitals for different spins, which leads to a scheme intermediate between band theory and valence bond method and, by means of a single parameter, one can obtain an essential lowering of the energy curve and the correct asymptotic behavior for separated atoms or constituents.

Abstract: In the theory of the electronic structure of crystals, the fundamental features of the band theory, the valence bond method, and the tight‐binding approximation are reviewed. The band theory is studied on the basis of the Hartree‐Fock scheme, and the Bloch functions are formed by a projection technique. The main methods for calculating Hartree‐Fock functions in a solid are briefly discussed. The advantages and disadvantages of the band theory and the valence bond method are emphasized, and special attention is paid to the correlation error.In connection with the tight‐binding approximation, the importance of the continuum part and of the approximate linear dependencies is stressed. It is shown that a complete orthonormal set of translationally connected atomic orbitals may be constructed as a convenient basis for this approach. The implication of the virial theorem in interpreting the cohesive properties of the ionic crystals is further emphasized.Some recent refinements of band theory are then discussed. It is shown that a large part of the correlation error can be removed by permitting ``different orbitals for different spins.'' This leads to a scheme intermediate between band theory and valence bond method and, by means of a single parameter, one can obtain an essential lowering of the energy curve and the correct asymptotic behavior for separated atoms or constituents. This approach may be generalized to an extension of the Hartree‐Fock scheme, where the total wave function is defined as a projection of a Slater determinant.The band theory can be further refined and connected to the exact solution of the many‐electron Schrodinger equation of the crystal by means of an extension of the self‐consistent‐field scheme, utilizing the so‐called reaction operator here exactly defined by means of a simple partitioning technique. The various types of self‐consistent field theories are finally compared.