Data from: Nanotube structure of AsPS4–xSex (x = 0, 1)

Single-wall nanotubes of isostructural AsPS4−xSex (x = 0, 1) are grown
from solid-state reaction of stoichiometric amounts of the elements. The
structure of AsPS4 was determined using single-crystal X-ray diffraction
and refined in space group P1. The infinite, single-walled AsPS4 nanotubes
have an outer diameter of ≈1.1 nm and are built of corner-sharing PS4
tetrahedra and AsS3 trigonal pyramids. Each nanotube is nearly hexagonal,
but the ≈3.4 Å distance between S atoms on adjacent nanotubes allows them
to easily slide past one another, resulting in the loss of
long-range order. Substituting S with Se disrupted the crystallization of
the nanotubes, resulting in amorphous products that precluded the
determination of the structure for AsPS3Se. 31P solid-state NMR
spectroscopy indicated a single unique tetrahedral P environment in AsPS4
and five different P environments all with different degrees of Se
substitution in AsPS3Se. Optical absorption spectroscopy revealed an
energy band gap of 2.7 to 2.4 eV for AsPS4 and AsPS3Se, respectively.
Individual AsPS4 microfibers showed a bulk conductivity of 3.2 × 10−6 S/cm
and a negative photoconductivity effect under the illumination of light
(3.06 eV) in ambient conditions. Thus, intrinsic conductivity
originates from hopping through empty trap states along the length of the
AsPS4 nanotubes.

等结构的AsPS₄₋ₓSeₓ（x=0、1）单壁纳米管通过化学计量比单质的固相反应制备得到。AsPS₄的晶体结构采用单晶X射线衍射法解析，并在空间群P1中完成精修。该无限长单壁AsPS₄纳米管外径约为1.1 nm，由共顶点连接的PS₄四面体与AsS₃三角锥构筑而成。单根纳米管近似呈六边形结构，但相邻纳米管上硫原子间约3.4 Å的间距使其可轻易相互滑移，最终导致长程有序性的丧失。用硒取代硫会破坏纳米管的结晶过程，最终得到无定形产物，使得AsPS₃Se的晶体结构无法被解析。固态31P核磁共振（NMR）光谱分析表明，AsPS₄中仅存在一种独特的四面体配位磷环境，而AsPS₃Se中则存在五种因硒取代程度不同而各异的磷配位环境。光学吸收光谱测试结果显示，AsPS₄与AsPS₃Se的能带带隙分别为2.7 eV与2.4 eV。单根AsPS₄微纤维的体相电导率为3.2×10⁻⁶ S/cm，在环境条件下经3.06 eV光照时表现出负光电导效应。由此可知，其本征电导率源于沿AsPS₄纳米管轴向的空陷阱态跳跃传导。