Crystal growth and X-ray structure determination of Rb3Bi2I9

Crystal and Electronic Structures of Complex Bismuth Iodides A3Bi2I9 (A = K, Rb, Cs) Related to Perovskite: Aiding the Rational Design of Photovoltaics

“…For all three phases, the densities calculated from the structural data correspond nicely to the experimental densities which were determined by He gas displacement measurements (Supporting Information). For K 3 Bi 2 I 9 21 and Cs 3 Bi 2 I 9 , 22 an excellent agreement with previous crystal structure reports was obtained, while the redetermination of the structure of Rb 3 Bi 2 I 9 led to a new structure model with the space group P 2 1 /n instead of the previously reported model in space group P c. 20 From X-ray diffraction of Rb 3 Bi 2 I 9 single crystals, this space group Crystal structures of (a) BiI 3 (R3), 64 (b) Cs 3 Bi 2 I 9 (P 6 3 /mmc), 22 and (c) Rb 3 Bi 2 I 9 (P 2 1 /n) with empty squares marking the unoccupied metal positions of the perovskite aristotype. Small spheres represent I − , large spheres are counter cations A + , and spheres inside polyhedra are Bi 3+ .…”

“…Previously, methods for growing single crystals, typically at high temperatures from the melts, have been reported. 20,21,23 We have found that single crystals of up to 1 mm can also be obtained at very mild solvothermal conditions in ethanol at 120…”

“…Additional structural data as well as information about the transformation between the group subgroup pair P 2 1 /c (P 2 1 /n) and P c are included in the Supporting Information. It is likely that Sidey et al 20 reported the Rb 3 Bi 2 I 9 crystal structure in the acentric space group Pc as a consequence of the crystal twinning in the crystal studied. The atomic positions and unit cell derived in this work are very similar to this previously published structure.…”

“…In the present work however, PBE without SOC was applied for the monoclinic systems to reduce computation time. Computations of the NMR observables for two structure models of Rb 3 Bi 2 I 9 , this work's model in P 2 1 /n and the P c model reported by Sidey et al, 20 were performed with the plane wave and PAW-based QUAN-TUM ESPRESSO package 57 together with the QE-GIPAW extension. QE-GIPAW computes the magnetic shielding at each nucleus using the gauge-including projector augmented wave formalism, 58,59 and the electric field gradient at each nuclear site using standard PAW expressions.…”

“…[17][18][19] Despite their much simpler composition, the optoelectronic properties of the ternary inorganic bismuth halides, with their most common family being the enneahalogenidometallate phases A 3 Bi 2 X 9 (A = K, Rb, Cs, or Tl; X = halide), have not been explored as extensively. Here we focus on the heavy alkali metal bismuth iodides A 3 Bi 2 I 9 for which the crystal structures have been reported: A = K, 20 Rb, 21 and Cs. 22 While the phase transitions in the Cs compound have been wellstudied, [23][24][25][26] only one report each for the K and Rb salt are to be found.…”