Transparent PLZT Ceramics Research Articles

Theoretical Density and PbO Deficiency of Pore-Free Transparent PLZT Ceramics

Lanthanum modified lead zirconate titanate (PLZT) ceramics are useful for electrooptic devices. However, as far as the defect structure of PLZT, there are still some arguments. In this study, the single phase widths of the completely pore-free transparent PLZT x/65/35 ceramics have been studied as a function of La concentration x. The PbO loss data corresponding to the upper and lower limits of the single phase from the starting composition were measured by the thermogravimetric method in controlling atmospheres. Also, the density approach corresponding to the single phase region has been tried for the almost completely porefree specimens prepared by Two-Stage Processing. The defect structures are discussed so as to fit in both the single phase regions. Some electrical properties are measured for specimens with various PbO deficiency within the single phase region.

Vacuum sintering of transparent piezo-ceramics

Transparent PLZT ceramics were fabricated by a new vacuum-atmosphere sintering method combining vacuum sintering and atmosphere sintering. Cold pressed powders were first sintered in vacuum for 15 – 30 minutes at 1150 – 1180°C and then heated in air for 60 – 90 hours with atmosphere powder. By this process, highly transparent PLZT ceramics were obtained. The production of nearly colourless small grain - size samples is possible.

Photochromic Effect in Fe‐Doped PLZT Ceramics

The photochromic effect in Fe‐doped transparent PLZT ceramics was investigated. The ceramics are darkened by irradiation with blue light having a wavelength of <4800 Å. The induced dark state is stable at room temperature and can easily be bleached back to its original transparent state by heat treatment at ∼200°C. The photo induced optical density change depends strongly on the transparency of the ceramic. Response times for the darkening and bleaching have been investigated as a function of the excitation light intensity and the temperature of the ceramic. A tentative model explaining the observed effect is proposed, and the photochromic mechanism is discussed on the basis of a charge‐transfer process between the photo activated Fe3+ and Fe4+ impurities in the ceramic.

Investigations of domain proccesses by the depolarization of linearly polarized light in transparent plzt ceramics

Investigations of domain proccesses by the depolarization of linearly polarized light in transparent plzt ceramics

Electrical, optical and acoustic properties of PLZT ceramics by two-stage processing

Abstract A new sintering technique for transparent PLZT ceramics was developed which uses a unique two-stage process involving both vacuum hot pressing for a short time (first stage) and atmosphere sintering (second stage). By this process we obtained highly transparent, virtually colorless, and extremely pore-free PLZT 9/65/35. The quality of materials fabricated by this process depends strongly upon the method of controlling the liquid phase excess lead oxide in the grain boundaries.

An improved preparation technique for ferroelectric ceramics

Abstract Many potential applications of ferroelectric ceramics are limited by porosity. Ceramics prepared by a standard technique exhibit pores and other inhomogeneities the size of which is up to 20 fim. The paper describes an improved technique which includes an improvement of powder preparation as well as sintering in an evacuated oven. Density of resulting PZT-ceramics is larger than 99.8% of theoretical density. In addition an increase of dielectric constant and piezoelectric coupling factor could be observed. The described technique was used for the preparation of high stability piezoelectric ceramics, of substrates for acoustic surface wave devices, and of transparent PLZT-ceramics.

Improvements in Atmosphere Sintering of Transparent PLZT Ceramics

An improved atmosphere sintering process was developed for fabricating large transparent PLZT plates for electrooptic applications. Cold‐pressed 9/85/35 PLZT slugs were sintered in O2 in Pt crucibles for ∼45 min at 1180°C and were then heat‐treated in air for 60 h at 1200°C in Al2O3 crucibles containing PbZrO3 atmosphere powder. Transparent plates as large as 8.4 cm in diameter and I cm thick were thus fabricated. A mechanism is proposed which qualitatively accounts for the success of this process.

Fabrication of Transparent Electrooptic PLZT Ceramics by Atmosphere Sintering

PLZT electrooptic ceramics were fabricated by a unique atmosphere sintering technique. The ceramics produced were significantly more transparent than those obtained by ordinary O2 sintering methods; in fact, they were comparable in transparency to those obtained by hot‐pressing. To achieve good transparency, the powder must be batched with excess PbO, which at the sintering temperature is present as a liquid phase at the grain boundaries. Sintering was conducted at 1200°C for 60 h in an atmosphere containing O2 and a relatively high partial pressure of lead oxide.