Structural Diversity and Magnetic Properties of Hybrid Ruthenium Halide Perovskites and Related Compounds

Abstract

There has been a great deal of recent interest in extended compounds containing Ru3+ and Ru4+ in light of their range of unusual physical properties. Many of these properties are displayed in compounds with the perovskite and related structures. Here we report an array of structurally diverse hybrid ruthenium halide perovskites and related compounds: MA2RuX6 (X=Cl or Br), MA2MRuX6 (M=Na, K or Ag; X=Cl or Br) and MA3Ru2X9 (X=Br) based upon the use of methylammonium (MA=CH3NH3+) on the perovskite A site. The compounds MA2RuX6 with Ru4+ crystallize in the trigonal space group R3‾m and can be described as vacancy‐ordered double‐perovskites. The ordered compounds MA2MRuX6 with M+ and Ru3+ crystallize in a structure related to BaNiO3 with alternating MX6 and RuX6 face‐shared octahedra forming linear chains in the trigonal P3‾m space group. The compound MA3Ru2Br9 crystallizes in the orthorhombic Cmcm space group and displays pairs of face‐sharing octahedra forming isolated Ru2Br9 moieties with very short Ru–Ru contacts of 2.789 Å. The structural details, including the role of hydrogen bonding and dimensionality, as well as the optical and magnetic properties of these compounds are described. The magnetic behavior of all three classes of compounds is influenced by spin–orbit coupling and their temperature‐dependent behavior has been compared with the predictions of the appropriate Kotani models.

Chemical Control of Spin‐Orbit Coupling and Charge Transfer in Vacancy‐Ordered Ruthenium(IV) Halide Perovskites

“…where x = ξ / k B T and ξ is the spin‐orbit coupling strength. This behavior is universal for magnetic ions such as Ru IV and has been successfully used to quantify spin‐orbit coupling strengths in a range of complexes [10, 32, 33] . The A 2 Ru X 6 compounds reported here follow d 4 Kotani behavior extremely well (Figure 3), with the effective magnetic moments dropping sharply at low temperatures, corresponding to the ground state J eff =0.…”

“…A few Ru IV halides have also been explored. The temperature‐dependent magnetism of (NH 4 ) 2 RuCl 6 was reported, [32] and we have recently demonstrated the single‐ion behavior of the hybrid (CH 3 NH 3 ) 2 Ru X 6 ( X =Cl or Br) compounds [10] . The magnetism of some alkali‐metal hexahaloruthenates(IV) was reported, [33] but no dependence on the identity of the alkali‐metal or the halide was noted.…”

Temperature-Responsive Photoluminescence and Elastic Properties of 1D Lead Halide Perovskites R- and S-(Methylbenzylamine)PbBr3

“…Metal halide perovskites (MHPs) are attracting considerable interest owing to their excellent optoelectronic properties tunable at a molecular level [ 1 , 2 , 3 , 4 , 5 ]. The merits of a high absorption coefficient, good defect resistance, and ease of synthesis [ 6 , 7 , 8 ] have led to their wide application in solar cells [ 9 , 10 , 11 , 12 ], photodetectors [ 13 , 14 , 15 ], and light-emitting diodes [ 16 , 17 , 18 , 19 , 20 , 21 ]. Currently, the number of reported three-dimensional (3D) MHPs is very limited due to their structural requirement by the Goldschmidt tolerance factor [ 6 , 7 , 8 ].…”

“…The merits of a high absorption coefficient, good defect resistance, and ease of synthesis [ 6 , 7 , 8 ] have led to their wide application in solar cells [ 9 , 10 , 11 , 12 ], photodetectors [ 13 , 14 , 15 ], and light-emitting diodes [ 16 , 17 , 18 , 19 , 20 , 21 ]. Currently, the number of reported three-dimensional (3D) MHPs is very limited due to their structural requirement by the Goldschmidt tolerance factor [ 6 , 7 , 8 ]. To overcome this restriction, low-dimensional (LD) MHPs, including zero-dimensional (0D), one-dimensional (1D), and two-dimensional (2D) MHPs, are being widely explored.…”

Spectroscopic Identification of Disordered Molecular Cations in Defect Perovskite‐Like ALn(HCO2)(C2O4)1.5 (Ln=Tb‐Er) Phases

“…Amongst the hybrid halide perovskites inclusion of a diamine has been shown to lead to random vacancies on the B and X‐sites, which suppresses undesirable ion diffusion [30,31] . Vacancy ordered double hybrid perovskites are also known, adopting the K 2 PtCl 6 ‐type structure in which half the B‐sites are vacant in an ordered fashion [32,33] . Despite this interest in defects there are scarce studies on hybrid perovskite phases with ordered anion vacancies.…”