Optimal La3⁺ window in Pb₁₋ₓLaₓTiO₃: Balancing structural, microstructural, dielectric, and optical properties

Abstract

Obtaining transparent ferroelectric ceramics requires balancing electrical and optical properties, typically achieved through controlled doping. In this study, densified lead titanate (PT) ceramics doped with different concentrations of lanthanum (PLT18, PLT20, and PLT22) were synthesized and characterized structurally, dielectrically, and optically. All compositions crystallized in a tetragonal perovskite structure; with increasing lanthanum content, the Curie temperature decreased and the diffuseness exponent (γ) increased, indicating a progressively more diffuse transition. Despite these trends, the maximum permittivity remained high and the dielectric loss was generally low. Among the compositions studied, PLT20 defined an optimal window for combined electrical and optical performance: it attained ~ 40% transmittance at 650 nm while exhibiting reduced influence of ferroelectric domain activity under operating conditions and a minimal contribution from secondary phases relative to adjacent compositions. This combination yields stable dielectric behavior with moderate loss and supports reliable electro-optic functionality. Collectively, the structural, dielectric, and optical results for the PLT20 ceramic establish it as a practical composition for lead-based transparent ferroelectric components.