Thermal expansions of ceramics in the system Pb1-x(La1/2K1/2)xTiO3

The solid solution limit of Pb1-x(La1/2K1/2)(x)TiO3 was determined in the composition range of 0 less than or equal to x < 1. The compounds of Pb1-x(La1/2K1/2)(x)TiO3 were indexed in a tetragonal system for 0 less than or equal to x less than or equal to 0.4 and indexed in a cubic one for 0.45 less than or equal to x < 1 at room temperature. A tiny amount of La2Ti2O7 pyrochlore phase was detected in the sample Pb1-x(La1/2K1/2)(x)TiO3 for x = 1.0. The lattice parameters of Pb1-x(La1/2K1/2)(x)TiO3 (x = 0.1, 0.2, 0.3, 0.4, 0.6, 0.8) were determined by high temperature XRD, and their intrinsic thermal expansion coefficients were obtained in the temperature range from room temperature to 900degreesC. In the temperature range from room temperature to the Curie point, the compound Pb-0.8(La1/2K1/2)(0.2)TiO3 has a low intrinsic thermal expansion coefficient (-7.1 x 10(-6) degreesC(-1)), which is the value closest to zero in all the investigated compounds. The (ferroelectric) Curie temperatures of Pb1-x(La1/2K1/2)(x)TiO3 could be predicted from our experimental results for 0 less than or equal to x less than or equal to 0.4. (C) 2003 Elsevier B.V. All rights reserved.