Showing papers on "Dielectric published in 1969"
05 May 1969
TL;DR: In this article, the coplanar waveguide is used for non-reciprocal magnetic device applications because of the built-in circularly polarized magnetic vector at the air-dielectric boundary between the conductors.
Abstract: A coplanar waveguide consists of a strip of thin metallic film on the surface of a dielectric slab with two ground electrodes running adjacent and parallel to the strip. This novel transmission line readily lends itself to nonreciprocal magnetic device applications because of the built-in circularly polarized magnetic vector at the air-dielectric boundary between the conductors. Practical applications of the coplanar waveguide have been experimentally demonstrated by measurements on resonant isolators and differential phase shifters fabricated on low-loss dielectric substrates with high dielectric constants. Calculations have been made for the characteristic impedance, phase velocity, and ripper bound of attenuation of a transmission line whose electrodes are all on one side of a dielectric substrate. These calculations are in good agreement with preliminary experimental results. The coplanar configuration of the transmission system not only permits easy shunt connection of external elements in hybrid integrated circuits, but also adapts well to the fabrication of monolithic integrated systems. Low-loss dielectric substrates with high dielectric constants may be employed to reduce the longitudinal dimension of the integrated circuits because the characteristic impedance of the coplanar waveguide is relatively independent of the substrate thickness; this may be of vital importance for Iow-frequency integrated microwave systems.
910 citations
TL;DR: In this paper, the Clausius-Mossotti theory of the electronic dielectric constant of diatomic crystals is extended to the case of the diamond, zincblende, wurtzite, and rock-salt types.
Abstract: Electronegativity difference is redefined as a scaling parameter, generalizing the concept of valence difference. A procedure for its evaluation is developed in terms of the dielectric constants of diatomic crystals. A simple alternative to the Clausius-Mossotti theory of the electronic dielectric constant is developed in terms of this concept. The effect of $d$-electron states and of hydrostatic pressure are discussed, and procedures for their approximate evaluation are developed. The treatment is extended to 68 crystals of the diamond, zincblende, wurtzite, and rock-salt types; values of the electronegativity parameter are tabulated for these crystals.
829 citations
TL;DR: In this paper, the dielectric constants, electrical conductivity, specific heat, and pyroelectric coefficients of ferroelectric Sr1−xBaxNb2O6 (SBN) were investigated as a function of temperature in the range 10°-500°K, and as a result of the Sr/Ba composition of the material.
Abstract: The dielectric constants, electrical conductivity, specific heat, and pyroelectric coefficients of ferro‐electric Sr1−xBaxNb2O6 (SBN) are investigated as a function of temperature in the range 10°–500°K, and as a function of the Sr/Ba composition of the material. A simple technique for measuring absolute pyroelectric coefficients and spontaneous polarizations of ferroelectrics is described. The electric field and frequency dependence of the dielectric properties are also investigated. The theory of pyroelectric detection is discussed from a materials point of view, and the experimental data are considered in terms of the usefulness of SBN as a pyroelectric detector of electromagnetic radiation.
702 citations
TL;DR: In this article, light transmission through a curved dielectric rod of rectangular cross section embedded in different dielectrics is analyzed in closed-form, though approximate form, in three ranges: (i) small cross section guides such as a thin glass ribbon surrounded by air; making its width 1 percent of the wavelength, most of the power travels outside of the glass; the attenuation coefficient of the guide is two orders of magnitude smaller than that of glass; and the radius of curvature that doubles the straight guide loss is around 10,000Λ.
Abstract: Light transmission through a curved dielectric rod of rectangular cross section embedded in different dielectrics is analyzed in closed, though approximate form. We distinguish three ranges: (i) Small cross section guides such as a thin glass ribbon surrounded by air—Making its width 1 percent of the wavelength, most of the power travels outside of the glass; the attenuation coefficient of the guide is two orders of magnitude smaller than that of glass, and the radius of curvature that doubles the straight guide loss is around 10,000Λ. (ii) Medium cross section guide for integration optics—It is only a few microns on the side and capable of guiding a single mode either in low loss bends with short radii of curvature or in a high Q closed loop useful for filters. Q's of the order of 108 are theoretically achievable in loops with radii ranging from 0.04 to 1 mm, if the percentage refractive index difference between guide and surrounding dielectric lies between 0.1 and 0.01. (iii) Large cross section guides—They are multimode and are used in fiber optics. Conversion to higher order modes are found more significant than radiation loss resulting from curvature.
699 citations
TL;DR: In this paper, a new ellipsometry technique was developed for the measurement of the dielectric constants of high reflectivity metals, which is especially well suited to the measurements of high-reflectivity metals.
Abstract: We report the development of a new ellipsometry technique which is especially well suited to the measurement of the dielectric constants of high reflectivity metals. Modulation methods are used to permit the measurement of a differential reflectance parameter which does not decrease in sensitivity in the high reflectivity limit as do the usual reflectance parameters measured with standard techniques. In addition the ellipsometer is faster than previous methods, being capable of recording the relevant data in a few minutes as the wavelength is swept continuously over a range of several thousand angstroms. The precision of the dielectric constants so measured is 1% in most cases. The polarization modulation technique, upon which the ellipsometer is based, is presented in detail, with emphasis on its wider applicability to any problem involving the study of dichroic phenomena.
532 citations
TL;DR: In this paper, measurements have been made of the charge density produced on dielectric surfaces by contact with metals of known difference in work function in vacuo and the injected charge density is dependent on the metal work function and, therefore, described by electron transfer for all the materials examined.
Abstract: Measurements have been made of the charge density produced on dielectric surfaces by contact with metals of known difference in work function in vacuo. The injected charge density is dependent on the metal work function and, therefore, described by electron transfer for all the materials examined. Values of work function are presented for PVC, 485 ev; polyimide, 436 ev; PTFE, 426 ev; polycarbonate, 426 ev; PET, 425 ev; polystyrene, 422 ev; and nylon 66, 408 ev. The positions of some of these materials in the familiar `triboelectric series' are readily described by their work functions.
521 citations
TL;DR: In this article, the stability of a uniform orientation pattern in electric fields parallel or perpendicular to the preferred axis is investigated, with respect to a complete set of sinusoidal perturbations and including distortional and (stabilizing) magnetic torques.
Abstract: It is shown by way of model orientation patterns how conduction in nematic liquid crystals may cause a torque per unit volume that more than offsets the dielectric torque felt in the insulating state. This conduction‐induced torque arises from an anisotropy of the conductivity or of the dielectric constant. It is partly dielectric but its more important part is shear‐induced, the shear flow being a consequence of space charge which is generated by and interacts with the applied electric field. The stability of a uniform orientation pattern in electric fields parallel or perpendicular to the preferred axis is investigated, with respect to a complete set of sinusoidal perturbations and including distortional and (stabilizing) magnetic torques. The analysis shows that the shear‐induced torque cannot be treated like its dielectric counterpart. It depends in a peculiar way on the direction of the perturbational wave vector and may contain a nonconservative contribution. Formulas for the instability threshold, ...
508 citations
TL;DR: In this article, a new energy parameter was introduced to describe dispersion of the electronic dielectric constant, which was found to obey an extraordinarily simple empirical relation in the more than 50 ionic and covalent crystals for which reliable refractive-index dispersion data are available.
Abstract: A new energy parameter ${\mathcal{E}}_{d}$ is introduced to describe dispersion of the electronic dielectric constant. This dispersion energy is found to obey an extraordinarily simple empirical relation in the more than 50 ionic and covalent crystals for which reliable refractive-index dispersion data are available. Based on this result we derive a structure-dependent electronic dielectric response function consisting of constant optical-frequency conductivity with high-and low-frequency cutoffs.
353 citations
TL;DR: In this paper, an analytically simple self-consistent description of the modes of a circular dielectric structure is presented, resulting in an asymptotic technique.
Abstract: An asymptotic technique is presented, resulting in an analytically simple self-consistent description of the modes of a circular dielectric structure. When the dielectric difference between the rod and surrounding medium is small, the asymptotic expressions are valid for all frequencies. Even when the inside dielectric constant is twice the outside, less than a 10 percent error is usually involved. A simple functional expression for the eigenvalues of both the circular rod and the dielectric slab results from the analysis, thus eliminating the need for numerical or graphical methods.
295 citations
TL;DR: In this article, audio and radio-frequency dielectric constants, of far infrared transmission spectra and of refractive indices through the visible spectrum were used to assess critically the current theoretical treatments and interpretations of the electronic structures and interionic forces in ionic crystals.
Abstract: Dielectric and spectroscopic measurements have been made on the alkali halides and several thallium and silver halides, at 2 and 290 $^\circ$K, in order to determine, for each, values for the parameters which characterize the dispersion of the dielectric constant due to lattice vibrations. These have then been used to assess critically the current theoretical treatments and interpretations of the electronic structures and interionic forces in ionic crystals. The measurements were of audio and radio-frequency dielectric constants, of far infrared transmission spectra and of refractive indices through the visible spectrum.
Patent•
21 Apr 1969
TL;DR: In this article, the authors propose a transition from the wave of the launch to the line of the dielectric of the Dielectric, which gradually decays over the line.
Abstract: THE INVENTION ESSENTIALLY CONSISTS OF PROVIDING A SUBSTANTIALLY CONTINUOUS TRANSITION OF THE WAVE OF THE LAUNCHER TO THE WAVE OF THE LINE BY SURROUNDING THE LINE WHEN EMERGING FROM THE LAUNCHER WITH A PREFERABLY LOWLOSS DIELECTRIC OF RELATIVELY LARGE DIAMETER CORRESPONDING TO THE DIAMETER OF THE LAUNCHER, WHICH IS GRADUALLY DECREASED WHILE EXTENDING OVER THE LINE OF THE DIAMETER OF THE DIELECTRIC COATING OF THE LINE ITSELF.
TL;DR: In this paper, the angular distribution of the radio-frequency electric field of a short antenna in a plasma in a static magnetic field was observed to vary with incident frequency, cyclotron frequency, and plasma frequency in agreement with simple plasma dielectric theory.
Abstract: We report experimental observation of resonance cones in the angular distribution of the radio-frequency electric field of a short antenna in a plasma in a static magnetic field. The cone angle is observed to vary with incident frequency, cyclotron frequency, and plasma frequency in agreement with simple plasma dielectric theory. We discuss the relationship of these cones to the limiting phase- and group-velocity cones which appear in the theory of plane wave propagation.
TL;DR: In this article, the optical, electrical, and structural properties of orthorhombic perovskite polymolybium permixtures have been investigated and the properties of all three forms of polymorphic permixtures are described.
Abstract: Large single crystals of and can be grown by Czochralski pulling from the melt. In the case of a small amount of excess is used to avoid incongruent crystallization. Both materials show pronounced cleavage very similar to that of mica. The electrical properties of are also very similar to those of mica, making this material a possible mica substitute as well as being an interesting new dielectric material in its own right. is orthorhombic Pmmm, with , not the previously reported perovskite structure. Other characteristics determined include optical, mechanical, and chemical properties. When exposed to atmospheres between about 25 and 85% relative humidity, becomes a trihydrate, with higher hydration above about 85% relative humidity. Optical, electrical, and structural properties of all three forms of are described.
Abstract: The effects of pressures up to 4 kbar on the density, dielectric constant, and viscosity of n-pentane, n-hexane, n-octane, cyclopentane, methylcyclohexane, and 2,2-dimethylbutane (DMB) were measure...
TL;DR: In this paper, the authors investigated the effects of small additions of Fe2O3 to lead zirconate-lead titanate ceramics with compositions between 45 and 60 mol% lead ZIRconate and showed that the dielectric constant and dissipation factor for both rhombohedra1 and tetragonal materials were decreased by addition of iron oxide.
Abstract: An investigation of the effects of small additions of Fe2O3 to lead zirconate-lead titanate ceramics with compositions between 45 and 60 mol% lead zirconate has shown that, with 2 moles of PbO to balance each mole of Fe2O3, the solubility of Fe2O3 was about 0.8 wt% in compositions near the tetragonal-rhombohedra1 boundary. The dielectric constant and dissipation factor for both rhombohedra1 and tetragonal materials were decreased by addition of iron oxide, whereas the mechanical quality factor and frequency constant were increased. The dependence of the electromechanical properties on grain size was qualitatively similar for both undoped and iron oxide-doped materials; the presence of iron oxide inhibited grain growth and lowered the limiting grain size below which the electromechanical properties change rapidly with grain size.
TL;DR: A unified treatment of various properties of ferroelectric crystals in their non-polar phases, typified by BaTiO3, KH2PO4 and NaNO2, is given in this article.
Abstract: A unified treatment is given of various properties of ferroelectric crystals in their non-polar phases, typified by BaTiO3, KH2PO4 and NaNO2. Certain relations are established between measurable dielectric and scattering properties. Critical scattering is discussed in terms of lattice dynamics.
TL;DR: In this paper, the optical and dielectric properties of liquid water in the vacuum ultraviolet have been determined from spectral data and Fresnel's equations, and the spectral region from 3000 to 1050 A for three angles of incidence.
Abstract: Two methods have been used to determine the optical and dielectric properties of liquid water in the vacuum ultraviolet. In the first, the reflectance of water in equilibrium with its vapor at 1°C was measured in the spectral region from 3000 to 1050 A for three angles of incidence. In the second, water was placed against the plane surface of a transparent semicylinder, which formed one side of a sealed cell, and the reflectance was measured at the water–semicylinder interface. Real and imaginary parts of the complex index of refraction and dielectric constant were deduced from the data and Fresnel's equations. Peaks in the complex dielectric constant occur at 8.3 and 9.6 eV. Though the absorption bands cannot at present be unambiguously assigned, possible mechanisms to explain the ultraviolet structure are presented.
TL;DR: In this article, the Clausius-Mossotti polarization for all liquids at constant temperature shows a linear decrease with increasing density, and only isopentane and toluene show a temperature dependence of Clausiusmossotti polarities at constant density consistent with the presence of a permanent dipole moment.
Abstract: The dielectric constant and density have been measured simultaneously for carbon tetrachloride, carbon disulfide, isopentane, and toluene. The Clausius–Mossotti polarization for all liquids at constant temperature shows a linear decrease with increasing density. Only isopentane and toluene show a temperature dependence of the Clausius–Mossotti polarization at constant density consistent with the presence of a permanent dipole moment. The dipole moments derived from the constant density data are 0.105 D for isopentane and 0.332 D for toluene. Also, the Bottcher–Onsager equation is shown to be incompatible with the measured data.
TL;DR: In this paper, experimental evidence is presented bearing on the low current conduction and on the rapid electrical switching phenomena that have been found in thin films of certain amorphous chalcogenide semiconducting materials.
Abstract: : Experimental evidence is presented bearing on the low current conduction and on the rapid electrical switching phenomena that have been found in thin films of certain amorphous chalcogenide semiconducting materials. The principal findings are that (1) the low current conduction consists of an 'ohmic' region linear with voltage and an exponentially varying nonlinear region, both of which arise from the same conduction process; (2) at voltages just below switching, the equivalent parallel capacitance of the film becomes negative; and (3) a field-influenced dielectric phase transition is implicated in the switching process. The phase transition temperature appears to be related to the glass transition temperature. (Author)
TL;DR: In this article, Penn's model of an isotropic semiconductor is used to calculate epsilon (q), the diagonal part of the static microscopic dielectric function, which is important in developing a quantum theory of lattice vibrations of diamond and zinc-blende crystals.
Abstract: : Penn's model of an isotropic semiconductor is used to calculate epsilon (q), the diagonal part of the static microscopic dielectric function. Penn's results have been extended beyond q = K sub F. This region is important in developing a quantum theory of lattice vibrations of diamond and zinc-blende crystals. Explicit results are given for the range 0 < q < 4K sub F. (Author)
Patent•
27 Feb 1969
TL;DR: In this article, a flexible multiple flat conductor electric cable fabricatable in long lengths with variable and uniform characteristic impedance is described, where the cable comprises a conductive layer, at least one flat dielectric layer continuous to each face of the conductive layers, and a ground plane layer contiguous to the outer face of each outermost layer.
Abstract: A flexible multiple flat conductor electric cable fabricatable in long lengths with variable and uniform characteristic impedance. The cable comprises a conductive layer, at least one flat dielectric layer continuous to each face of the conductive layer, and a ground plane layer contiguous to the outer face of each outermost dielectric layer. The flat conductor layer or continuous-wiring cable comprises a planar array of parallel spaced flat conductive strips preferably encapsulated in thin dielectric film. The dielectric layers are of materials, thicknesses, number, and configurations to provide a specific predetermined or a range of desired electrical characteristic values. The ground plane layer comprise conductive metal foil, optionally solid or perforated and optionally encapsulated. A flat conductor drain line may be disposed contiguously inward of the ground plane layer. The cable layers are loosely coupled by sewing or other interrupted bonding near the cable edges.
TL;DR: In this article, the resonant modes of GaAs junction lasers are obtained from a proposed model and compared with experimental results, based on an assumed laser medium whose dielectric constant varies both along and perpendicular to the junction plane.
Abstract: The resonant modes of GaAs junction lasers are obtained from a proposed model and compared with experimental results. Theoretical results are based on an assumed laser medium whose dielectric constant varies both along and perpendicular to the junction plane. The frequency separations of the transverse modes are found to be in very good agreement with presented high-resolution spectral measurements of stripe-geometry laser radiation. Furthermore, the theoretical field distributions are also in good agreement with observed transverse field variations reported previously. The laser output spectrum usually shows a number of "satellites" located adjacent to each longitudinal (Fabry-Perot) resonance. It is shown that each satellite represents the frequency of a transverse resonance having a different mode number along the junction plane and a corresponding Hermite-Gaussian intensity profile along the plane. Theory shows that the frequency separation of two adjacent satellites is related to the falloff rate of the dielectric constant along the junction plane. This focusing is measured from the intensity profile of a far-field pattern. From this information, the theoretical frequency separation is calculated and found to agree well with the measured separation of 6.4 GHz (0.15 A).
TL;DR: In this paper, it is argued that to treat the quantum-mechanical effects appearing at large wave vectors properly, the nonlocal dielectric functions which appear in the expressions for the surface impedance should be finite-electron-lifetime generalizations of the Lindhard dielectrics rather than those resulting from the Boltzmann equation.
Abstract: Our previous studies of the optical properties of an electron gas for which the surface scattering is specular have been extended. It is argued that to treat the quantum-mechanical effects appearing at large wave vectors properly, the nonlocal dielectric functions which appear in the expressions for the surface impedance should be finite-electron-lifetime generalizations of the Lindhard dielectric functions rather than those resulting from the Boltzmann equation. The striking anomalous absorption, due to plasmon excitation, occurring above the plasma frequency is emphasized in the discussion of the semi-infinite gas. For the case of a slab, the thickness dependence of the processes characterizing the optical properties is discussed. Electron-gas parameters representing both K and Al were used in the calculations, as were both types of dielectric functions mentioned above. A comparison of the present theory with some alternative theories, particularly that of Melnyk and Harrison, is presented.
TL;DR: In this article, the high-field electron distribution function for GaAs, its small-signal frequency response and its behavior in large sinusoidal electric fields were analyzed and the response speed is limited by the low scattering rate within the (000) valley.
Abstract: Numerical calculations have been made of the high-field electron distribution function for GaAs, its small-signal frequency response and its behavior in large sinusoidal electric fields-The response speed is limited by the low scattering rate within the (000) valley. With increasing frequency the threshold field for negative conductivity rises and the negative mobility and oscillator efficiency fall. The free-electron dielectric constant is positive at high fields, with a peak near the threshold field.
TL;DR: In this article, it was suggested that an anomaly observed by C.A. Mead in measurements of the capacitance of thin dielectric films, may be due to an electromechanical effect not accounted for in the classical, continuum theory of piezoelectricity.
TL;DR: In this paper, the finite-electron-lifetime expressions for the longitudinal and transverse dielectric functions of a freeelectron gas obtained by Lindhard in the self-consistent field approximation are examined.
Abstract: The finite-electron-lifetime expressions for the longitudinal and transverse dielectric functions of a free-electron gas obtained by Lindhard in the self-consistent-field approximation are examined. It is shown that these results are incorrect, and appropriate expressions are developed for the case where the system can be characterized by a single relaxation time.
TL;DR: In this article, a theory assuming specular scattering of electrons and incorporating nonlocal transverse and longitudinal dielectric functions predicts that a thin metallic film may exhibit anomalous optical properties due to the wave-vector-dependent structure in the longitudinal Dielectric function.
Abstract: A theory assuming specular scattering of electrons and incorporating nonlocal transverse and longitudinal dielectric functions predicts that a thin metallic film may exhibit anomalous optical properties due to the wave-vector-dependent structure in the longitudinal dielectric function.
TL;DR: In this paper, the dielectric properties and crystal chemistry of the bismuth titanates are discussed with reference to related structures, and the results of preliminary optical and electrical measurements are given.
Abstract: Ferroelectric compounds in the family have been prepared as ceramics and single crystals. The solid solution limit increases with ionic radius: exceeds 2 for La3+ and Pr3+ and approaches zero for the smaller Yb3+ and Lu3+ ions. The larger rare earth ions also stabilize the paraelectric phase. The dielectric properties and crystal chemistry of the bismuth titanates are discussed with reference to related structures, and the results of preliminary optical and electrical measurements are given.