Infrared nonlinear optical (IR NLO) materials are the key materials in the modern laser frequency conversion technology that are widely applied in many fields. Yet, the major issue is lacking of high performance materials with large nonlinear susceptibility and high laser damage threshold, which are two correlated and contradictory parameters. Here, the novel dual ion substitution synergy leads to the discovery of Ba₄MGa₄Se₁₀Cl₂ (M = Zn, 1; Cd, 2; Mn, 3; Cu/Ga, 4; Co, 5; and Fe, 6), crystallizing in the tetragonal . Polycrystalline 1–4 exhibits very strong IR second harmonic generations (SHG). (1: 59×; 2: 52×; 4: 39×; and 3: 30× that of IR benchmark NLO material AgGaS₂). Remarkably, the laser-induced damage threshold of 1 is 143.6 MW cm^–2, roughly 17 times that of benchmark AgGaS₂. These distinguish 1 as a new promising NLO material. In addition, 1, 2, and 4 illustrate the coexistence of NLO and photoluminescence properties. Especially, 3 demonstrate for the first time the coexistence of triple properties (NLO, photoluminescence, and magnetism) in a single crystal structure. The insights of the driving force of the synergetic substitution, SHG origin, and microscopic contributions of the building units open a new route to discovering novel multi-functional NLO materials.

A novel type of supertetrahedral connectivity is exhibited by the 72-atom discrete supercubooctahedron in (Cs₆Cl)₂Cs₅[Ga₁₅Ge₉Se₄₈] (1), which undergoes both cation and anion exchange, as revealed by unambiguous single-crystal X-ray diffraction data. Electronic-structure studies helped to understand the Ge/Ga distribution.

Thermoelectric (TE) materials have continuously attracted interest worldwide owing to their capability of converting heat into electricity. However, discovery and design of new TE material system remains one of the greatest difficulties. A TE material, TmCuTe₂, has been designed by a substructure approach and successfully synthesized. The structure mainly features CuTe₄-based layers stacking along the c axis that are separated by Tm³⁺ cations. Such an intrinsic Cu site vacancy structure undergoes a first-order phase transition at around 606 K driven by the energetically favorable uniform Cu atom re-distribution on the covalent CuTe₄-based layer substructure, as shown by crystal structure simulations and variable-temperature XRD data. Featured with very low thermal conductivity (ca. 0.6 W m⁻¹ K⁻¹), large Seebeck coefficient (+185 μV K⁻¹), and moderate electrical conductivity (220 S cm⁻¹), TmCuTe₂ has a maximum ZT of 0.81 at 745 K, which is nine times higher than the value of 0.09 for binary Cu₂Te, thus making it a promising candidate for mid-temperature TE applications. Theoretical studies uncover the electronic structure modifications from the metallic Cu₂Te to the narrow gap semiconductor TmCuTe₂ that lead to such a remarkable performance enhancement.

Uniform Cu₂S nanodisks have been synthesized from a well-characterized layered copper thiolate precursor by structure-controlling solventless thermolysis at 200–220 °C under a N₂ atmosphere. The development from small Cu₂S nanoparticles (diameter ≈3 nm) to nanodisks (diameter 8.3 nm) and then to faceted nanodisks (diameter 27.5 nm, thickness 12.7 nm) is accompanied by a continuous phase transition from metastable orthorhombic to monoclinic Cu₂S, the ripening of small particles by aggregation, and finally the crystallization process. The growth of the nanoproduct is constrained by the crystal structure of the precursor and the in situ-generated thiol molecules. Such controlled anisotropic growth leads to a nearly constant thickness of faceted nanodisks with different diameters, which has been confirmed by TEM observations and optical absorption measurements.