Black Current: Structure, Characterization, and Optoelectronic Properties of Ce3Cl3[MoO6]. Issue 33 (14th May 2019)

• Record Type: Journal Article
• Authors: Dorn, Katharina V.; Blaschkowski, Björn; Bamberger, Heiko; van Slageren, Joris; Doll, Klaus; Claus, Ralf; Matsumoto, Yosuke; Takagi, Hidenori; Hartenbach, Ingo
• Is Part Of: Chemistry. Volume 25:Issue 33(2019)
• Page Start: 7921
• Page End: 7926
• Publication Date: 2019-05-14
• Subjects: cerium -- density functional calculations -- EPR spectroscopy -- optoelectronic properties -- oxidomolybdates; Chemistry -- Periodicals; 540
• DOI: 10.1002/chem.201901038
• Languages: English
• ISSNs: 0947-6539

Abstract

Abstract: The admixture of CeO2, Ce, CeCl3, and MoO3 with an excess of LiCl as flux in evacuated silica ampules leads to large black single crystals as well as a black microcrystalline powder of Ce3 Cl3 [MoO6 ] after tempering at 850 °C for three days. The title compound crystallizes in the hexagonal space group P 63 / m ( a= 934.93(4), c= 538.86(2) pm) with two formula units per unit cell. The crystal structure consists of rather unusual trigonal‐prismatic [MoO6 ] 6− units besides Ce 3+ ions in a tetra‐capped trigonal‐prismatic coordination, formed by four Cl − and six O 2− ions. The black color is related to an optical band gap of 1.35(2) eV, which was determined by diffuse reflectance spectroscopy and confirmed by theoretical calculations. The low band gap between the 4f 1 state of cerium (HOMO) and the 5d 0 state of molybdenum (LUMO) gave rise to the idea of electronic excitation between these two states by IR irradiation, creating a drop in the resistivity of the material, which was detected by appropriate measurements. Abstract : Switchable black : The black compound Ce3 Cl3 [MoO6 ] was obtained through solid‐state reactions and comprises trigonal‐prismatic [MoO6 ] 6− entities. The material shows notable spectroscopic properties regarding the dependency of its specific resistivity under irradiation with IR light (see figure).