Fabrication and ferroelectric/dielectric properties of La-doped PMN-PT ceramics with high optical transmittance

Relaxor ferroelectric 0.75(Pb 1–3 x /2 La x )(Mg 1/3 Nb 2/3 )O 3 -0.25(Pb 1–3 x /2 La x )TiO 3 (La 3+ :PMN-PT x /75/25, where x =2.8, 3.0, 3.5, and 4.0   mol% of La 3+ ) transparent ceramics were fabricated by the combination of oxygen atmosphere pressureless sintering and hot-pressing sintering process. The optical transmittances of above four ceramics are higher than 60% at the wavelength of 500–900   nm. La 3+ :PMN-PT 3.0/75/25 exhibits the highest transparency around 70% at 900   nm which is very close to the theoretical transmittance 71%. Each of the four ceramics exhibits the pure perovskite phases. They show fully dense microstructures and their relative densities are higher than 99.8%. The ferroelectric and dielectric measurements indicate that these four ceramics exhibit relaxation characteristics. With increasing La 3+ content, (200) peak in XRD patterns shifts to higher angles and the average grain size increases, while the temperature Tε max corresponding to the maximum ε r , the remanent polarizations P r and coercive fields E c decrease gradually.