Modelling IR-spectra of single-phase polycrystalline materials with random orientation – Supplementations and refinements for optically uniaxial crystallites
Abstract:The IR-reflectance spectra of a bulk sample of randomly oriented polycrystalline fresnoite (Ba2TiSi2O8) are presented. The sample was prepared by Spark Plasma Sintering from a powder consisting of optically large crystallites. The spectra are of notable higher quality than those of conventionally prepared samples, especially those of the cross-polarization terms. The spectra were modelled by a 4 ×4-matrix-formalism [T. G. Mayerhöfer, J. Opt. A: Pure Appl. Opt. 4, 540 (2002)], which was refined for optically uniaxial crystals, resulting in a correct prediction of the relative peak-intensities of the cross-polarization terms. The modelling was carried out with two different orientational averaging schemes. The comparison between modelled and measured spectra revealed that the use of any weighing factor is unjustified in case of orientational averaging of the IR-optical properties of solids.
Document Type: Research Article
Affiliations: 1: Institut für Physikalische Chemie, Friedrich-Schiller-Universität, Lessingstraße 10, D-07743 Jena, Germany 2: Department of Inorganic Chemistry, Arrhenius Laboratory, Stockholm University, S-106 91 Stockholm, Sweden 3: Otto-Schott-Institut für Glaschemie, Friedrich-Schiller-Universität, Fraunhoferstraße 6, D-07743 Jena, Germany 4: Institut für Oberflächenmodifizierung e.V., Permoserstrasse 15, D-04318 Leipzig, Germany
Publication date: November 1, 2003