Cadmium germanium arsenide (CdGeAs2) refractive indices, dielectric constant

2005 ◽  
pp. 1-2
Author(s):  
Keyword(s):  
Dielectric Constant ◽  
Refractive Indices ◽  
Cadmium Germanium Arsenide

Optical Properties of Low Dielectric Constant Polyimides and Effects of Orientation

1993 ◽  
Vol 323 ◽  
Author(s):  
David C. Rich ◽  
Peggy Cebe ◽  
Anne K. St. Clair
Keyword(s):  
Dielectric Constant ◽  
Refractive Index ◽  
Optical Properties ◽  
Fluorine Content ◽  
Polymer Chains ◽  
Low Dielectric Constant ◽  
Refractive Indices ◽  
Electronic Polarizability ◽  
Low Dielectric ◽  
Preferential Alignment

AbstractControl of the refractive index in low dielectric constant polyimides through modification of chemistry and structure was investigated. The optical refractive indices of several low dielectric constant polyimides were measured, and the effects of orientation on optical anisotropy were determined. Refractive index in these polyimides was found to decrease with increasing fluorine content due primarily to the low electronic polarizability of the fluorine-carbon bonds. In zone drawn polyimides, refractive index was found to increase substantially in the direction of the draw, but decrease substantially normal to the draw direction. This was explained in terms of the preferential alignment of the polymer chains.

Defect-Induced Properties of Doped Alpha Alumina Samples

2008 ◽  
Vol 55-57 ◽  
pp. 801-804 ◽  
Author(s):  
P. Jantaratana ◽  
Pisutti Dararutana ◽  
Wiwat Wongkokua ◽  
Sorapong Pongkrapan ◽  
P. Wathanakul
Keyword(s):  
Dielectric Constant ◽  
Parallel Plate ◽  
Reference Sample ◽  
Dielectric Constants ◽  
Refractive Indices ◽  
Plate Method ◽  
Physico Chemical ◽  
Voltage Frequency ◽  
Chemical Conditions ◽  
Alpha Alumina

The dielectric constant values of a set of synthetic alpha alumina samples doped with Cr and Be were determined using parallel plate method. The voltage frequency was selected at 1 MHz. When Cr was doped to the sample, the dielectric constant was increased due to the increase in polarizations of the sample, whereas the Be-doped one showed the decrease in dielectric constant cf. the undoped synthetic alpha alumina (reference sample). Experiments on doping alpha alumina with both elements showed increasing in dielectric constant compared to the undoped reference sample, i.e., Cr has more influence to the dielectric constant value. Dielectric constants of a set of natural sapphires were also measured and compared to those obtained from the synthetic ones. The results of both natural and synthetic samples varied in the same direction. It suggests, however, that the geological origins of the samples are needed to be considered. This is due to the differences in physico-chemical conditions of their formations that would have influenced partitioning of trace elements as well as evolving of defects in natural samples. Increasing of the R1 and R2 photoluminescence wavelengths and decreasing of refractive indices of the doped samples cf. those of the reference sample were obtained from the experiments.

scholarly journals Электрические и оптические свойства нерелаксированных гетероэпитаксиальных структур InAs-=SUB=-1-x-=/SUB=-Sb-=SUB=-x-=/SUB=-

2019 ◽  
Vol 53 (7) ◽  
pp. 922
Author(s):  
Р.Р. Гусейнов ◽  
В.А. Танрывердиев ◽  
G.L. Belenky ◽  
G. Kipshidze ◽  
Е.H. Алиева ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Dielectric Constant ◽  
Magnetic Fields ◽  
Energy Range ◽  
Electron Concentration ◽  
Wide Temperature Range ◽  
Refractive Indices ◽  
Heteroepitaxial Structures ◽  
Galvanomagnetic Properties ◽  
Shubnikov De Haas Oscillations

The electrical and galvanomagnetic properties of unrelaxed heteroepitaxial structures of InAs1-xSbx (x = 0.43 and x = 0.38) were studied in a wide temperature range of 5-300K and magnetic fields up to 8 T. The band gap of the composition InAs0.57Sb0.43 was estimated from the thermo-activation dependence of the electrical conductivity, and is equal to 120 meV. The electron concentration in InAs1-xSbx (n=6·1016 cm-3 for InAs0.62Sb0.38 and n=5·1016 cm-3 for InAs0.57Sb0.43) determined from the Hall effect and consistent with the electron concentration calculated from Shubnikov-de Haas oscillations. Also, implemented spectral ellipsometric studies of unrelaxed heteroepitaxial structures of InAs1-xSbx (x = 0.43 and x = 0.38) in the photon energy range of 1-6 eV. The spectral dependences of the imaginary and real parts of the dielectric constant are determined. The dispersion dependences of the refractive indices and extinction are calculated and given.

scholarly journals The refractive indices of calcite and aragonite

1924 ◽  
Vol 105 (732) ◽  
pp. 370-386 ◽  
Keyword(s):  
Dielectric Constant ◽  
Electric Field ◽  
Wave Train ◽  
Relative Displacement ◽  
Effective Dielectric Constant ◽  
Refractive Indices ◽  
Double Refraction ◽  
Isotropic Media ◽  
Cubic System ◽  
The Moment

1. The two crystalline forms of calcium carbonate, calcite and aragonite, have been analyzed by X-ray methods, and they both display strong double refraction. It is therefore of interest to see whether the large difference in the refractive indices for light polarized in different planes can be explained by the atomic arrangements in the crystals. The electron theory of dielectric media supposes that the atoms of the medium become polarized under the influence of an external electric field. The positive and negative components of the atom suffer a relative displacement, which is equivalent to the development of an electric doublet placed at or near the centre of the atom. The moment of the doublet is proportional to the strength of the electric field in its immediate neighbourhood, the constant of proportionality being characteristic of the atom considered. The local field which causes the polarization of the atom may for convenience be divided into two parts, the first being the force arising from charges in the field, including the doublets of the polarized medium not in the immediate neighbourhood of the atom, the second being the force arising from the doublets in its immediate neighbourhood. In isotropic media, such as liquids or amorphous solids, the average effect of the neighbouring doublets will be same what-ever the direction of the electric field which causes polarization. In Crystals of lower symmetry than that of the cubic system, this will not be the case. The influence of the neighbouring doublets on an atom will depend on the orientation of the electric field with reference to the crystal axes; this will be the case both for the alternating fields of a wave train as well as for a steady field. The effective dielectric constant will therefore depend upon the direction of the electric vector of the waves, and since the velocity of light is inversely proportional to the square root of the dielectric constant, the crystal will display double refraction.

Crystal optics

2004 ◽  
Author(s):  
Robert E. Newnham
Keyword(s):  
Dielectric Constant ◽  
Refractive Index ◽  
Acoustic Waves ◽  
Electromagnetic Waves ◽  
Constitutive Relations ◽  
Dielectric Anisotropy ◽  
Refractive Indices ◽  
Double Refraction ◽  
Light Waves ◽  
Wave Normal

Calcite (CaCO3) is a beautiful transparent mineral that readily cleaves into rhombohedra. Images viewed through a thin slice of a cleaved calcite crystal are split into two images, an effect known as double refraction, or birefringence. Birefringence is the most obvious manifestation of optical anisotropy in crystals. For any given wave normal, there are two light waves, transversely polarized in mutually perpendicular directions, traveling with different velocities, and consequently different refractive indices. Double refraction is caused by dielectric anisotropy. For transparent crystals like calcite, the magnetic susceptibility is small and the permeability μ ≌ μ0, the permeability of free space. In this class of materials the refractive index n = c/v = where c is the speed of light in vacuum, v the velocity of light in the crystal, and K is the dielectric constant measured at optical frequencies. Refractive indices of transparent materials lie between 1 and 3. Electromagnetic waves differ from acoustic waves in that there are, for a given wave normal, two waves rather than three. In the acoustic case there are, in general, two quasitransverse waves and a quasilongitudinal wave. Starting with Maxwell’s Equations and the material constitutive relations, the propagation of electromagnetic waves through transparent crystals are described in terms of the refractive indices, wave normals, and polarization directions.

scholarly journals Optical Properties of Perovskite Thin Film

2019 ◽  
Vol 30 (1) ◽  
pp. 174
Author(s):  
Bahjat B. Kadhim ◽  
Ali Zamil Manshad
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Dielectric Constant ◽  
Optical Properties ◽  
Energy Gap ◽  
Refractive Indices ◽  
Ambient Conditions ◽  
Step Method ◽  
Solar Cell Application ◽  
Gap Energy

Methyl-ammonium lead tri iodide (CH3NH3PbI3) perovskite thin films have been prepared by solution processing. Thin film after deposited in the laboratory ambient conditions by drop casting, it prepared by two step method PbI2 and CH3NH3I at the glass substrate. The analysis provides: the absorption coefficient, extinction coefficient, refractive indices, real and imaginary components of the dielectric constant of the CH3 NH3 PbI3 films, energy gap. Energy gap of perovskite thin films is reached 1.8 that is very important for solar cell application.

Dielectric Property of Barium-Bearing Glasses Based on Thai Resources Doped with Nd3+

2011 ◽  
Vol 216 ◽  
pp. 124-127
Author(s):  
Won In Krit ◽  
Pisutti Dararutana
Keyword(s):  
Dielectric Constant ◽  
Refractive Index ◽  
Dielectric Property ◽  
Absorption Spectra ◽  
Raw Material ◽  
Refractive Indices ◽  
Constant Density ◽  
Local Resource

Barium-bearing glass samples were fabricated using raw material from the beneficiation of local resource. Nd2O3was added in various concentrations. Dielectric constant, density, refractive index, and absorption spectra of the glass samples were measured. It was found that the densities and refractive indices increased with increasing Nd2O3contents. The dielectric constant and absorption spectra were plotted and discussed.

The spindle stage: A powerful optical tool

1988 ◽  
Vol 46 ◽  
pp. 52-53
Author(s):  
Mickey E. Gunter ◽  
F. Donald Bloss
Keyword(s):  
Significant Error ◽  
Optical Data ◽  
Refractive Indices ◽  
Axis Of Rotation ◽  
Polarizing Microscope ◽  
Microscope Stage

A single, reasonably homogeneous, nonopaque 30-to-300 μm crystal, mounted on a spindle stage and studied by immersion methods under a polarizing microscope, yields optical data frequently sufficient to identify and characterize a substance unequivocally. The data obtainable include (1) the orientation of the crystal's principal vibration axes and (2) its principal refractive indices, to within 0.0002 if desired, for light vibrating along these principal vibration axes. Spindle stages tend to be simple and relatively inexpensive, some costing less than $50. They permit rotation of the crystal about a single axis which is parallel to the microscope stage. This spindle or S-axis is thus perpendicular to the M-axis, namely the microscope stage's axis of rotation.A spindle stage excels when studying anisotropic crystals. It orients uniaxial crystals within minutes and biaxial crystals almost as quickly so that their principal refractive indices - ɛ and ω (uniaxial); α, β and γ (biaxial) - can be determined without significant error from crystal misorientation.

Microstructural characterization of YBaCuO Films on LaAlO3 substrates

1989 ◽  
Vol 47 ◽  
pp. 180-181
Author(s):  
E. L. Hall ◽  
A. Mogro-Campero ◽  
N. Lewis ◽  
L. G. Turner
Keyword(s):  
Dielectric Constant ◽  
Single Crystal ◽  
Film Growth ◽  
Microstructural Characterization ◽  
Lattice Parameter ◽  
Film Plane ◽  
Substrate Material ◽  
High Loss ◽  
Amorphous Substrates ◽  
High Dielectric

There have been a large number of recent studies of the growth of Y-Ba-Cu-O thin films, and these studies have employed a variety of substrates and growth techniques. To date, the highest values of Tc and Jc have been found for films grown by sputtering or coevaporation on single-crystal SrTiO3 substrates, which produces a uniaxially-aligned film with the YBa2Cu3Ox c-axis normal to the film plane. Multilayer growth of films on the same substrate produces a triaxially-aligned film (regions of the film have their c-axis parallel to each of the three substrate <100> directions) with lower values of Jc. Growth of films on a variety of other polycrystalline or amorphous substrates produces randomly-oriented polycrystalline films with low Jc. Although single-crystal SrTiO3 thus produces the best results, this substrate material has a number of undesireable characteristics relative to electronic applications, including very high dielectric constant and a high loss tangent at microwave frequencies. Recently, Simon et al. have shown that LaAlO3 could be used as a substrate for YBaCuO film growth. This substrate is essentially a cubic perovskite with a lattice parameter of 0.3792nm (it has a slight rhombohedral distortion at room temperature) and this material exhibits much lower dielectric constant and microwave loss tangents than SrTiO3. It is also interesting from a film growth standpoint since it has a slightly smaller lattice parameter than YBa2Cu3Ox (a=0.382nm, b=c/3=0.389nm), while SrTiO3 is slightly larger (a=0.3905nm).

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