Eu2 P2 S6 : The First Rare-Earth Chalcogenophosphate Exhibiting Large Second-Harmonic Generation Response and High Laser-Induced Damage Threshold

Metal chalcogenophosphates are receiving increasing interest, specifically as promising infrared nonlinear optical (NLO) candidates. Here, a rare-earth chalcogenophosphate Eu₂ P₂ S₆ crystallizing in the monoclinic noncentrosymmetric space group Pn was synthesized using a high-temperature solid-state method. Its structure features isolated [P₂ S₆ ]^4- dimer, and two types of EuS₈ bicapped triangular prisms. Eu₂ P₂ S₆ exhibits a phase-matchable second-harmonic generation (SHG) response ≈0.9×AgGaS₂ @2.1 μm, and high laser-induced damage threshold of 3.4×AgGaS₂ , representing the first rare-earth NLO chalcogenophosphate. The theoretical calculation result suggests that the SHG response is ascribed to the synergetic contribution of [P₂ S₆ ]^4- dimers and EuS₈ bicapped triangular prisms. This work provides not only a promising high-performance infrared NLO material, but also opens the avenue for exploring rare-earth chalcogenophosphates as potential IR NLO materials.

A highly distorted HgS4 tetrahedron-induced moderate second-harmonic generation response of EuHgGeS4

The first Eu,Hg-based chalcogenide EuHgGeS₄ exhibits phase-matchable SHG activity with an intensity ∼0.9 times that of AgGaS₂.

The size effect to O2- -Ce4+ charge transfer emission and band gap structure of Sr2 CeO4

Sr₂ CeO₄ phosphors with different crystalline sizes were synthesized by the sol-gel method or the solid-state reaction. Their crystalline size, luminescence intensity of O^2- -Ce⁴⁺ charge transfer and energy gaps were obtained through the characterization by X-ray diffraction, photoluminescence spectra, as well as UV-visible diffuse reflectance measurements. An inverse relationship between photoluminescence (PL) spectra and crystalline size was observed when the heating temperature was from 1000°C to 1300°C. In addition, band energy calculated for all samples showed that a reaction temperature of 1200°C for the solid-state method and 1100°C for sol-gel method gave the largest values, which corresponded with the smallest crystalline size. Correlation between PL intensity and crystalline size showed an inverse relationship. Band structure, density of states and partial density of states of the crystal were calculated to analyze the mechanism using the cambrige sequential total energy package (CASTEP) module integrated with Materials Studio software.

Recent progress in crystalline metal chalcogenides as efficient photocatalysts for organic pollutant degradation

Recent progress in crystalline metal chalcogenides as efficient visible-light-driven photocatalysts for aqueous organic pollutant degradation is reviewed.

Band gap tuning from an indirect EuGa2S4 to a direct EuZnGeS4 semiconductor: syntheses, crystal and electronic structures, and optical properties

Novel EuZnGeS₄, with a direct band gap, can be obtained via simple substitution from EuGa₂S₄, with an indirect band gap.

A series of pentanary inorganic supramolecular sulfides (A3X)[MB12(MS4)3] (A = K, Cs; X = Cl, Br, I; M = Ga, In, Gd) featuring B12S12 clusters

A series of multinary thiogallate- or thioindate-closo-dodecaborates synthesized by solid state reactions demonstrate second-harmonic generation behaviors.