Lanthanum-doped lead zirconate titanate

Pressure sintering techniques have also been used to fabricate transparent lanthanum-doped lead zirconate titanate (PLZT) ceramics in air and in oxygen-gas atmosphere [31]. The microstructure of the sintered body was not uniform it was completely dense near the surface, but it was porous at the center. The thickness of the dense layer increased with sintering time and oxygen-gas pressure in the sintering atmosphere. Vaporization of PbO from the specimen surface and resultant formation of lattice vacancies were attributed to this microstructural evolution. Diffusion of the gas trapped in the pores was also important in determining the thickness of the dense layer. When the PLZT specimen was sintered in air at 1200 °C for 8 h, the thickness of the dense layer was 0.25 mm. Therefore, if the specimen thickness was 0.5 mm, the whole specimen was dense and transparent. When the specimen was sintered in an oxygen-gas atmosphere under the same conditions, the specimen thickness increased markedly. 

PLZT = lanthanum-doped lead zirconate-lead titanate. 

Zhao H, Sun XD, Zhang JW, Zou YYK, Li KWK, Wang YY et al (2011) Lasing action and optical amplification in Nd " doped electrooptic lanthanum lead zirconate titanate ceramics. Opt Express 19 2965-2971... 

Doping PZT with lanthanum ions (La replaces Pb ) shifts the morphotropic boundary to higher x-values and lowers the Curie temperature of the oxidic alloy. At 5% La, the Curie temperature can even drop below room temperature if X is high enough. The solid has become cubic and paraelectric and no longer has a permanent electric dipole moment at room temperature but is very polarizable. This material is called PLZT (short for lead lanthanum zirconate titanate) and is used for its nonlinear optical properties, e.g., in doubling the frequency of laser radiation. 

The Glass and Ceramics Institute of the Spanish CSIC carried out an analytical study of new materials used in structural and electrical ceramics, the stoichiometries and impurity contents of which were highly interesting because of their influence on the physico-chemical properties and service response of the pieces [24]. The specific materials studied were tetragonal zirconia stabilized with ceria and yttria (Y-TZP/Ce) lead titanate modified with gadolinium and doped with manganese (Gd-PT) and lead titanate-zirconate modified with lanthanum (PLZT). The first is a structural ceramic and the other two are electrical ceramics. 

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