Index of refraction of doped batio₃, crystals

The indices of refraction in the cubic phase of a crystal of BaTiO3doped with Fe, and one doped with Mn, as well as (Ba0.56Sr0.44)TiO3are reported and compared to that of pure BaTiO3. In all cases similar precursor effects are seen approximately 100°C above Tc. Thus, this effect seems to be an intrinsic property of BaTiO3, and not directly caused by impurities. The connection of these effects to overdamped phonons is discussed. © 1990, Taylor & Francis Group, LLC. All rights reserved.