Electrooptic, PLZT ceramics

Haertling, G.H. and Land, C.E. (1971) Hot-pressed (Pb,La)(Zr,Ti)03 ferroelectric ceramics for electrooptic applications, J. Am. Ceram. Soc. 54, 1. This is the original citation for transparent PLZT ceramics. Kaiser, P. (1973) Spectral losses of unclad fibers made from high-grade vitreous silica, Appl. Phys. Lett. 23, 45. Developed the MCVD process. 

Tatebayashi T, Yamamoto T, Sato H (1991) Electrooptic variable focal-length lens using PLZT ceramic. Appl Opt 30 5049-5055... 

Fogel, Y., BarChaim, N., Seidman, A. (1980). Longitudinal electrooptic effects in slim-loop and linear PLZT ceramics. Appl. Opt, Vol. 19, No. 10, pp. 1609-1617. 

The PLZT ceramics show large changes in birefringence by switching the polarization and these materials are of potential use in optical memories and displays. " However, the electrooptic properties utilized for such devices depend on the grain size. ... 

These lead-based materials (PZT, PLZT, PMN) form a class of ceramics with either important dielectric, relaxor, pie2oelectric, or electrooptic properties, and are thus used for appHcations ia actuator and sensor devices. Resistive properties of these materials ia film form mirror the conduction processes ia the bulk material. Common problems associated with their use are low dielectric breakdown, iacreased aging, and electrode iajection, decreasiag the resistivity and degrading the properties. 

Approximately ten years ago, it was first reported by Haertling and Land (jj that optical transparency was achieved in a ferroelectric ceramic material. This material was, in reality, not just one composition but consisted of a series of compositions in the lanthanum modified lead zirconate-lead titanate (PLZT) solid solution region. The multiplicity of compositions, each with different mechanical, electrical and electrooptic properties has led to a decade of study in defining the chemical and structural nature of these materials in understanding the phenomena underlying their optical and electrooptic properties and in evaluating the practicality of the large number of possible applications (2-12),... 

Electrooptic Properties, The electrooptic properties of the PLZT materials are intimately related to their ferroelectric properties. Consequently, varying the ferroelectric polarization with an electric field such as in a hysteresis loop, produces a change in the optical properties of the ceramic. In addition, the magnitude of the observed electrooptic effect is dependent on both the strength and direction of the electric field,... 

Mixed-metal oxides constitute a significant proportion of electroceramics (e.g., ferroelectrics or superconductors). In addition, electrooptical ceramics such as Pb(LaZrTi)03(PLZT), PbNb2/3Mg1/303(PNM), and Bi4Ti3Ol2 received considerable attention. It may be pointed out that the low-temperature SG route appears to be more suitable for lead containing materials in view of the comparatively more volatile characteristic of lead oxide, which tends to disturb the desired stoichiometry of the multimetal oxide material involving lead, prepared by the MOCVD procedure. 

Haertling, G.H. (1991) Electrooptic ceramics and devices , in Engineered Materials Handbook Volume 4 Ceramics and Glasses, ASM International, p. 1124. Haertling and Land (1971) developed the PLZT system of transparent ferroelectric ceramics. 

Much of this early effort dealt with modulator technology that is considered too slow (1-100 kilohertz) for high-speed applications such as optical interconnection and memory read/write. This includes modulators based on electrooptic effects in ferroelectric liquid crystals (ELCs) and in a ceramic containing lead, lanthanum, zinc, and titanium (PLZT). These electrooptic materials are bonded in some fashion to Si circuits to create hybrid SPAs. 

A special class of materials that is also ferroelectric are electrooptic ceramics. Materials such as lanthanum-modified lead zirconate titanate (PLZT) produce excellent electrooptic devices. These polycrystalline ceramics exhibit voltage-variable behavior—that is, they can be switched from optically transparent to opaque by the application of voltage. Most of these devices, which are used for shutters, modulators, and displays, are processed by hot pressing to full density. Experiments in many laboratories are being carried out to tape-cast these materials into thin sheets. The main problem encountered to date has been the ability to sinter to full density. The use of nanosized powders has helped in this regard. The ability to tape-cast large sheets could open a wide variety of applications for these materials. 

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