Nanowerk May 7, 2024
It is shown that structural disorder in the form of anisotropic, picoscale atomic displacements modulates the refractive index tensor and results in the giant optical anisotropy observed in BaTiS3. An international team of researchers (University of Southern California, Washington University, University of Wisconsin–Madison, UC Santa Barbara, Lawrence Berkeley National Laboratory, Oak Ridge National Laboratory, Switzerland) used scanning transmission electron microscopy to directly observe the globally disordered Ti a–b plane displacements and found them to be ordered locally over a few unit cells. First-principles calculations showed that the Ti a–b plane displacements selectively reduced the refractive index along the ab-plane, which had minimal impact on the refractive index along the chain direction, resulting in a giant enhancement in the optical anisotropy. According to the researchers their study opens a pathway for designing optical materials with high refractive index and functionalities such as large optical anisotropy and nonlinearity… read more. Open Access TECHNICAL ARTICLE
Optical anisotropy enhanced by Ti a–b plane displacements… Credit: Advanced Materials, 23 March 2024