Dielectric properties and structure of Bi4NbO8Cl and Bi4TaO8Cl

A New Bi4Mn1/3W2/3O8Cl Sillén–Aurivillius Intergrowth: Synthesis and Structural Characterisation by Quantitative Transmission Electron Microscopy

“…In Cc2m the 00l reflections with l = 2n + 1 are forbidden, whereas they are allowed in Cm2m. Figure 4 shows that 00l reflections with l = 2n + 1 are observed along the [010] and [1][2][3][4][5][6][7][8][9][10] [16] and lattice parameters a Ϸ b = 5.4 Å and c = 14.1 Å. (N = "net"; I = "ideal") …”

“…Around Bi(1) we can also observe an extension of the blobs corresponding to the O(3) Figure 5. Phase of the reconstructed exit wave along [1][2][3][4][5][6][7][8][9][10]. The bright dots correspond to the projected position of the different atoms.…”

“…Ackerman [9] revised these structures and assigned the orthorhombic space group P2 1 cn to the niobium oxychloride Bi 4 NbO 8 Cl (a Ϸ b = 5.49 Å and c = 28.75 Å) and the tetragonal space group P 4 (a = b = 3.84 Å; c = 14.35 Å) to PbBi 3 WO 8 Cl. Recently, Kusainova et al [10] reanalysed the structure of Bi 4 NbO 8 Cl by using neutron diffraction powder data in the same P2 1 cn space group (a = 5.44 Å, b = 5.49 Å and c = 28.81 Å). A study of the ferroelectric properties yields a T c of 765 K.…”

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

“…[9] are very close, indicating the obtained crystal is actually a pseudo-merohedral twin with domains existing along a four-fold axis. The formation of the pseudo-merohedral twin may cause a certain deviation of the O positions from the powder neutron data [16]. Figure 5b.…”

“…The structure of Bi 4 NbO 8 Cl was precisely refined by Lightfoot and his coworkers by using powder neutron data (space group: P2 1 cn, a = 5.4472(1) Å, b = 5.4901(1) Å, c = 28.8125(6) Å) [16]. As compared with the single-crystal work that yielded unusual bond valence sum values, e.g., 5.23 and 1.20 for Bi(3) and O(8), respectively [9], our refinement shows reasonable atomic positions as well as the bond valence sum, as shown in Table S3.…”