Showing papers on "Ferroelectric ceramics published in 1973"

Reflective‐mode ferroelectric‐photoconductor image storage and display devices

Abstract: A new type of image storage and display device, called the Fericon, is described in which the image is stored by means of electrically induced surface deformation in ferroelectric ceramics. The preferred method of viewing or projecting the stored image is by reflected light using Schlieren optics. The device has nonvolatile storage and the capability of selective erasure of the stored image.

Dielectric breakdown of shock‐loaded PZT 65/35

Abstract: The dependence of dielectric breakdown in shock‐loaded ferroelectric ceramics on both the shock amplitude and the electric field strength was investigated by employing shock reverberation techniques. In these experiments thick projectile disks were impacted on relatively thin specimens of hot‐pressed PZT 65/35 [Pb0.99Nb0.02(Zr0.65Ti0.35)0.98 O3] poled to 10, 20, and 30 μC/cm2. The principal results of this investigation are: (i) dielectric breakdown is not explicitly a function of stress for stress values in the region of this study (<23 kbar), (ii) breakdown is not instantaneous, (iii) for fields greater than the breakdown threshold (≈5 kV/mm) the time between introduction of the shock into the ferroelectric and onset of breakdown decreases rapidly with increasing electric field, (iv) electric fields generated by 10‐kbar shocks in specimens poled to 30 μC/cm2 are sufficient to cause breakdown, and (v) axial release waves can travel at a velocity as much as 15% faster than the initial stress wave.

Convolution scattering model for ferroelectric ceramics and other display media

Abstract: A theoretical model has been developed which is based upon the approximation that the multiple scattering from ferroelectric ceramics and other display media can be described in terms of geometrical optics. The model has been used to describe the scattering from PLZT, liquid crystals, and display screens and has agreed well with exprimental data. The scattering characteristics of several current display materials have been compared with regard to their use in wide-angle direct-view displays. The model has predicted the material parameters for new and more effective display materials. Measurements of a simulated new medium have shown close agreement with the predicted scattering characteristics.

Variations of the dielectric constant of pzt ferroelectric ceramics with electric field

Abstract: The electric field dependence of the dielectric constant and loss of PZT perovskite-type ceramics have been investigated. Measurements were performed at frequencies of 1, 10 and 100 kHz, and 1 MHz, at several temperatures below the Curie temperature. The bias characteristics of the dielectric constant have two peaks, related to the 180° domain reversal and the 90° domain rotations, and show a temperaturedependent asymmetry in the electric field direction. A dielectric relaxation is observed in the frequency dependence of the dielectric constant. A discussion of the results in terms of domain switching processes is presented.

Sputtered films for display devices

Abstract: Sputter deposition techniques have been developed which yield directly usable films of transparent conductors and of photoconductors for display devices. These devices have been primarily light-valve structures incorporating a ferroelectric ceramic plate or a liquid-crystal layer as the control medium. The deposition techniques may be modified to allow deposition on a variety of substrates including thermally sensitive materials. Transparent electrodes of sputter-deposited In 2-x Sn x O 3-y (ITO) have been deposited on PLZT ferroelectric ceramics, glasses, and other substrate materials. These ITO films have excellent adherence and are hard but may readily be polished and etched. The visible-light transmission is excellent and the absorption in the near infrared is controlled by the conductivity. Films of resistivity of 3 × 10-4Ω ċ cm have routinely been deposited on thermally stable substrates while film resistivity of 10-3Ω ċ cm may readily be obtained on thermally sensitive substrates. Sputter-deposited CdS, which has a peak photosensitivity near the 514.5-nm line of the Ar laser, has had a photoconductive gain of 4 × 103and a dark resistivity greater than 107Ω ċ cm. Similar sputter-deposition techniques have been used to fabricate device structures incorporating Cd 1-x Zn x S as the photoconductor. The Cd 1-x Zn x S composition has been varied to match film peak photosensitivity with laser emissions between 400 and 500 nm. These films have not been as photosensitive as CdS but they permit greater visible-light transmission, are sufficiently insensitive to projecting light sources so that they may be used in simultaneous read-write systems, and are capable of being used in real-time display systems. The dark resistivity of Cd 1-x Zn x S is dependent on composition but has exceeded 1012Ω ċ cm in all films.

Variable delay line based on the nonlinear characteristics of ferroelectric ceramics

Abstract: A distributed parameter delay line, with an electrically controlled delay time, was built and investigated. It uses the non-linear bias dependence of the dielectric constant of PZT ferroelectric ceramics. At room temperature, delay times of about 200 ns (at impedance level of 100 Ω) and variations of 10 percent with electric field were obtained.