Structural Modulation from Cu3PS4 to Cu5Zn0.5P2S8: Single-Site Aliovalent-Substitution-Driven Second-Harmonic-Generation Enhancement.

Diamond-like (DL) chalcophosphates, which possess the merits of impressive second-harmonic-generation (SHG) responses, strong laser-induced damage thresholds, and low melting points, are highly desirable for IR nonlinear-optical (NLO) applications. Herein, a new quaternary DL chalcophosphate, Cu5Zn0.5P2S8, is successfully discovered, taking known Cu3PS4 as the template via a single-site aliovalent-substitution strategy. It crystallizes in the orthorhombic system with noncentrosymmetric space group Pmn21, and the 3D DL structure is built by corner-shared [(Cu/Zn)S4], [CuS4], and [PS4] tetrahedra. Compared with its parent Cu3PS4, Cu5Zn0.5P2S8 exhibits a good phase-matching capability and a sharply enhanced SHG effect (10Cu3PS4) benefiting from partial Zn substitution. Moreover, the structure-performance relationships have been illustrated by means of theoretical investigations. Such an aliovalent-substitution strategy based on known DL semiconductors might be widely applied for the discovery of high-performance IR NLO crystals.

Quaternary Chalcohalides CdSnSX2 (X = Cl or Br) with Neutral Layers: Syntheses, Structures, and Photocatalytic Properties.

Inorganic chalcohalides are attracting a tremendous amount of attention because of their remarkable structural variety and desirable physical properties. Although great advances have been made in recent years, functional inorganic chalcohalides with two-dimensional neutral layers are still rare. Herein, two novel chalcohalides CdSnSX2 (X = Cl or Br) with high yields were obtained by reacting CdX2 with SnS using a traditional solid-state method at 823 K. Both of these chalcohalides adopt orthorhombic space group Cmcm (No. 63) with the following structural values: a = 4.014(4)-4.064(2) Å, b = 12.996(2)-13.746(3) Å, c = 9.471(2)-9.621(2) Å, V = 494.1(8)-537.5(2) Å3, and Z = 4. The prominent architectural feature is the unique two-dimensional [CdSnSX2] neutral layer consisting of composite [CdX2] and [SnS] sublattices that are connected alternately through the Cd-S-Sn bonds along the ac plane. The [CdX2] sublattice consists of a single octahedral chain of Cd-centered [CdX4S2] groups sharing cis-X edges, while the [SnS] sublattice consists of a bend-shaped chain of unusual [SnS2X2] units sharing vertices of S atoms. Significantly, each CdSnSX2 form (X = Cl or Br) shows high visible-light-induced photocatalytic activity for rhodamine B degradation, which is ∼7.0 times higher than that of nitrogen-doped TiO2 (TiO2-xNx) under the same experimental conditions. This discovery enriches the categories of inorganic chalcohalides and provides more choices of candidate materials for photocatalytic applications.