The modulated structure of the commensurate misfit-layer compound (BiSe)_1.09TaSe₂

Abstract

Single-crystal X-ray diffraction (Mo Ka radiation, A = 0.71073 A) was used to determine the structure of the commensurate inorganic misfit-layer compound (BiSe),,oTaSe2, a0 = 12/11 = 1.09. The struc-* Present address:

Transport properties of VSe2 monolayers separated by bilayers of BiSe

“…17 The charge is localized in Bi-Bi bonds at antiphase boundaries, which are thought to systematically occur due to the mutual accommodation of the lattice mismatch to form a commensurate structure. 16,18 We find that the VSe 2 layer(s) in a superlattice containing single layers of BiSe and VSe 2 is structurally similar to what was previously reported for [(SnSe) 1.15 ] 1 (VSe 2 ) 1 . The inplane diffraction pattern and layer positions from Rietveld refinement of the specular diffraction pattern are consistent with BiSe having a rocksalt type structure.…”

“…14 In (BiSe) 1.09 TaSe 2 , a gap of 0.3232 nm is found between the BiSe and the Se plane of TaSe 2 . 18 A gap of 0.289 (1) nm was reported in a recent paper containing the structure of a BiSe-NbSe 2 heterostructure. 24 The refined model is consistent with the targeted BiSe-VSe 2 heterostructure.…”

“…Clearly visible in these layers is a periodic anti-phase boundary, similar to that previously reported for (BiSe) 1.09 TaSe 2 . 16,18 Resistivity as a function of temperature is shown in prepared in this study along with that of bulk VSe 2 (Ref. 11) and [(SnSe) 1.15 ] 1 (VSe 2 ) 1 .…”

Correlation of Reduced Interlayer Charge Transfer with Antiphase Boundary Formation in BixSn1–xSe–NbSe2 Heterostructures

“…For appropriately oriented zone axes ([100] for a rectangular basal plane, [110] for a square basal plane lattice), the x = 0.73 sample shows a modulated structure characterized by periodic chains of Bi–Bi bonds, highlighted by the red arrows in the inset for this sample in Figure . The modulated structure was first observed in the BiS layers of (BiS) 1.08 TaS 2 by Wulff et al and later characterized in more detail for BiSe‐containing compounds by Wiegers and co‐workers , . The chains of Bi–Bi bonds are frequently referred to as antiphase boundaries .…”

“…However Bi‐containing misfit compounds with T = Ta or Nb do not exhibit significantly increased interlayer charge transfer relative to those with Pb or Sn, which has been explained as resulting from a structural modulation that occurs in the BiX layers characterized by periodic Bi–Bi bonds. Initially discovered by Wulff et al and further explored by Zhou and Petříček, for (BiX) 1+ δ TX 2 with T = Ta or Nb, the periodic Bi–Bi bonds were referred to as antiphase boundaries. Bond‐valence calculations by Petříček suggested that the antiphase boundaries allow the Bi in BiX layers to exist as a combination of nominally zero and trivalent states, resulting in charge localization and minimal interlayer charge transfer.…”