Single Crystal Growth of Sillén–Aurivillius Perovskite Oxyhalides Bi4NbO8X (X = Cl, Br)

Abstract

Sillén-Aurivillius perovskite Bi 4 NbO 8 X (X = Cl, Br) is a promising photocatalyst for water splitting under visible light, as well as a potential ferroelectric material. In this work, we investigate the crystal growth conditions by mainly varying soak temperature, soak time and cooling rate. Under the optimal conditions, we successfully obtained yellow platelet single crystals with an in-plane distance of several hundred microns. As opposed to conventional crystal growth, a moderate cooling is essential to suppress an evaporation of the Bi-O-Cl species from a melt zone. The single crystals of Bi 4 NbO 8 Br were also grown using a similar condition. We suggest that the knowledge obtained in this study can be generally applied to other Sillén-Aurivillius phases and related oxyhalides.

Orbital Engineering in Sillén–Aurivillius Phase Bismuth Oxyiodide Photocatalysts through Interlayer Interactions

“…However, the secondary mixing of the nominally empty Bi 6p orbitals results in energetic stabilization with a stereochemically active Bi lone pair. Most studies have focused on the valence band effects (e.g., BiVO 4 , 4,5 31 The interlayer Bi−Bi distance in the present materials (e.g., 3.9 Å in Bi 4 NbO 8 Cl) 32,33 is comparable to the Sn−Sn distance in SnO (3.8 Å), 31 which suggests that the interlayer interaction should also be considered in the present case. Such interlayer interaction can form a band (Figure 5).…”

Lone-Pair-Induced Intra- and Interlayer Polarizations in Sillén-Aurivillius Layered Perovskite Bi4NbO8Br

“…Subsequently, the P 2 1 cn model was suggested for Bi 4 M O 8 X ( M = Nb, Ta; X = Cl, Br) by Kusainova et al based on the NPD data . We previously analyzed the structure of Bi 4 NbO 8 Br based on the single-crystal XRD, but the refinement was not satisfactory due to the nanoscale domain formation in the ab plane …”

“…Singe crystals of Bi 4 NbO 8 Br were grown using the molten salt method . As-received powders of Bi 2 O 3 (Wako, 99.99%) and Nb 2 O 5 (Wako, 99.9%) were used as starting materials, while BiOBr was prepared with a soft liquid deposition method .…”

Flux Crystal Growth, Structure, and Optical Properties of the New Germanium Oxysulfide La4(GeS2O2)3

“…The La-O1 and La-S2 bond distances are 5% shorter and 7% longer, respectively, than the sum of the ionic radii of La 3+ and O 2-/S 2-. In contrast to these two lanthanum atoms, La3 is 12-fold coordinated with only oxygen atoms, forming a relatively symmetric icosahedron (dLa-O1 = 2.7159 (19) Å, dLa-O2 = 2.7524(16) Å). The bond distances between lanthanum and oxygen atoms agree well, as they are within 1% of the sum of their ionic radii.…”

“…The flux crystal growth method has been recognized as a useful technique for synthesizing new mixed-anion compounds, most of which do not readily occur in single-crystal form. − In particular, alkali or alkaline earth halides, which can be easily removed with water, are widely used as fluxes for the synthesis of a wide range of new oxychalcogenides, including nonlinear optical materials, , low-dimensional magnets, , and superconductors . Following the discovery of SrZn 2 S 2 O, we applied this approach to develop new optical oxysulfide materials based on d 10 metal-centered tetrahedra.…”