title: ABiO2X (A = Cd, Ca, Sr, Ba, Pb; X = halogen) Sillen X1 Series: Polymorphism Versus Optical Properties.
abstract: The Sillen X1 series of Bi(3+)A(2+)O2X (A = Cd, Ca, Sr, Ba, Pb; X = Cl, Br, I) compounds is composed of three main crystallographic types, namely, the tetragonal form (space group (S.G.) I4/mmm), the orthorhombic form (S.G. Cmcm), and the monoclinic form (S.G. P21/m). Because of Bi(3+)/A(2+) disorder the Bi(3+) based photoluminescence (PL) of the tetragonal polytypes is quenched at room temperature (RT). In the two other ordered forms, the Bi-O-Bi connectivity is different but limited, such that bluish/greenish emission occurs at RT in the monoclinic CdBiO2Cl and CaBiO2Cl and orthorhombic SrBiO2Cl and BaBiO2Cl phases. The crystal structure of BaBiO2Br was refined in the orthorhombic Cmcm space group and also shows RT emission. Focusing on the RT luminescent activity as a key parameter, the PL active compounds were investigated by means of density functional theory calculations and UV-visible reflectance spectroscopy. The influence of A and X ions on the excitation energy is discussed by analyzing the A-O-Bi and Bi-X bonding schemes and gives some insights for rational tuning of both the excitation and emission energies.
authors.affiliation: Univ. Lille, CNRS, Centrale Lille, ENSCL, Univ. Artois, UMR 8181 - UCCS - Unité de Catalyse et Chimie du Solide , F-59000 Lille, France.|Faculty of Science & Engineering, Inorganic Chemistry, University of Siegen , D-57068 Siegen, Germany.
authors.forename: Jacob
authors.initials: J
authors.lastname: Olchowka
authors.affiliation: Univ. Lille, CNRS, Centrale Lille, ENSCL, Univ. Artois, UMR 8181 - UCCS - Unité de Catalyse et Chimie du Solide , F-59000 Lille, France.
authors.forename: Houria
authors.initials: H
authors.lastname: Kabbour
authors.affiliation: Univ. Lille, CNRS, Centrale Lille, ENSCL, Univ. Artois, UMR 8181 - UCCS - Unité de Catalyse et Chimie du Solide , F-59000 Lille, France.
authors.forename: Marie
authors.initials: M
authors.lastname: Colmont
authors.affiliation: Faculty of Science & Engineering, Inorganic Chemistry, University of Siegen , D-57068 Siegen, Germany.
authors.forename: Matthias
authors.initials: M
authors.lastname: Adlung
authors.affiliation: Faculty of Science & Engineering, Inorganic Chemistry, University of Siegen , D-57068 Siegen, Germany.
authors.forename: Claudia
authors.initials: C
authors.lastname: Wickleder
authors.affiliation: Univ. Lille, CNRS, Centrale Lille, ENSCL, Univ. Artois, UMR 8181 - UCCS - Unité de Catalyse et Chimie du Solide , F-59000 Lille, France.
authors.forename: Olivier
authors.initials: O
authors.lastname: Mentré