Thin films of ferroelectric PZT were deposited on substrates of platinum and sapphire by means of rf sputtering, where the source material employed is a stoichiometric mixture of PbO, ZrO2, and TiO2 powders, contributing to, enhanced simplification and reproducibility over the hitherto reported processes. Relation between substrate temperature and crystal structure of the deposited films as well as the transition of crystal structure with heat treatment after film formation were investigated by X-ray diffraction. Studies of dielectric constant, loss tangent, remanent polarization and coercive field versus film thickness have indicated that both the dielectric constant and loss tangent settled to a constant value of ε=800, tanδ=1.0%, while the value of remanent polarization became no less than 15μC/cm2, and the coercive field grew to be more than 50 kV/cm in the vicinity and above a film thickness of about 2μm. Furthermore, heat treatment in an atmosphere of Ar-O2 has shown an ε=400, tanδ=1.2% and remanent polarization of 10μC/cm2 even at a film thickness of 0.5μm. Optical transmittance in the visible range observed is about 80%. for films deposited on sapphire. The studies also deal with electrical and optical characteristics versus film compositions analyzed by Auger Electron Spectroscopy.
Electroreflectance in undoped ZnTe single crystals grown from Zn solution is measured around the fundamental absorption edge at 80K and room temperature. The measurements are performed by using a Au-ZnTe Schottky-barrier configuration. The spectra at 80K are interpreted as being due to the excitonic and the band-to-band transitions. By analyzing the data at 80 K, the energies of the n=1 and n=2 exciton levels, and the band gap are determined to be 2. 369, 2. 376, and 2. 379eV, respectively, whereas from the spectra at room temperature, the band-gap energy is determined to be 2. 268 eV. Moreover, the binding energy and reduced mass of free excitons are determined to be 10 meV and 0.08mo, respectively.
A Doppler frequency shift of an electromagnetic wave scattered by a moving medium has already been investigated by many researchers. It seems, however, that the wave propa-gation in a stationary medium with a moving boundary has not been studied as yet. It can be shown that the frequency of an electromagnetic wave transmitted and reflected at a fast moving boundary is also shifted due to the Doppler effect. In this paper, the Doppler frequency shift is investigated theoretically and experimentally. The fast moving boundary can be produced by a large amplitude pulse incident upon a non-linear transmission line loaded with variable capacitance diodes. We have observed the spec-trum of a small amplitude signal transmitted through the boundary moving at a velocity of about twenty percent of the velocity of light. It is concluded that the Doppler frequency shift predicted theoretically agrees well with the one observed experimentally, both qualitatively and quantitatively. The results of this paper may present many useful data to the study of relativistic electromagnetism.
The phase variation of light transmitted through a nematic liquid crystal (MBBA) cell has been measured by means of a holographic interference microscope. From these experimental results the molecular alignment of nematic liquid crystal in the Williams domains mode (WDM) has been inves-tigated. It has been found that the molecular alignment in the WDM has a two-dimensional distribution with components along the applied electric field direction and the initial molecular alignment direction. Influence of sample thickness and excitation frequency of applied ac field on the voltage depen-dence of the molecular alignment has also been investigated.
Impurity lattice location using channeling effect seems to have been established as a powerful tool in solid state physics. In the present article, the principle of this application is briefly introduced and the techniques used in the experiments and analyses are summarized. Especially, each step of the analysis procedure is explained in detail. Successful examples for various impurity situations and remaining difficulties are also presented.
Geometrical relation of transitions and critical points in phase diagrams of the one com-ponent system was discussed thermodynamically. Only transition of odd order of the Ehrenfest classification is possible along a finite length of phase boundary. The critical points was defined as an intersecting point of a first order transition line and a stability limit of the state. So-called second order transition was critisized. The discussion was extended to three dimen-sional space, and some two dimensional phase diagrams were understood as the subspace. Ferro-electrics and antiferroelectrics were taken as pedagogical examples of three dimensional phase diagram and tricritical point.
Physical prperties of the one-dimensional organic conductor TTF-TCNQ are reviewed. Especially the properties of charge-density-waves and of the Peierls transition are shown in relation to the low-dimensionality of electrons. Also is discussed the possibility of the applica-tion of the one-dimensional conductors to the future electronic engineering.