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Black Current: Structure, Characterization, and Optoelectronic Properties of Ce 3 Cl 3 [MoO 6 ]
Author(s) -
Dorn Katharina V.,
Blaschkowski Björn,
Bamberger Heiko,
van Slageren Joris,
Doll Klaus,
Claus Ralf,
Matsumoto Yosuke,
Takagi Hidenori,
Hartenbach Ingo
Publication year - 2019
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201901038
Subject(s) - ion , trigonal prismatic molecular geometry , crystallography , band gap , triclinic crystal system , materials science , microcrystalline , cerium , crystal structure , ampoule , analytical chemistry (journal) , chemistry , octahedron , metallurgy , optoelectronics , organic chemistry , chromatography , composite material
The admixture of CeO 2 , Ce, CeCl 3 , and MoO 3 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 Ce 3 Cl 3 [MoO 6 ] after tempering at 850 °C for three days. The title compound crystallizes in the hexagonal space group P 6 3 / 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 [MoO 6 ] 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.