Thermodynamic study of the Cu-As-S system by EMF measurements with Cu<Subscript>4</Subscript>RbCl<Subscript>3</Subscript>I<Subscript>2</Subscript> as a solid electrolyte

The Cu-As-S system has been studied at temperatures from 300 to 370 K using emf measurements with Cu₄RbCl₃I₂ as a Cu⁺ ion conducting solid electrolyte, and its subsolidus phase diagram has been mapped out, including the ternary compounds Cu₃AsS₄, Cu₆As₄S₉, Cu₄As₂S₅, Cu₃AsS₃, and CuAsS. From the emf data, we have calculated the partial molar thermodynamic functions (D[`(G)]\Delta \bar G, D[`(H)]\Delta \bar H, and D[`(S)]\Delta \bar S) of the copper in the alloys and the standard thermodynamic functions of formation and standard entropies of the ternary compounds.     

New compounds Cu2MnTi3S8 and Cu2NiTi3S8 with thiospinel structure

Cu₂MnTi₃S₈ and Cu₂NiTi₃S₈ compounds were prepared by high-temperature synthesis. The crystal structure of these quaternary phases was investigated by X-ray powder diffraction. The compounds are described in the thiospinel structure (space group ) with the lattice constants a = 1.00353(1) nm (Cu₂MnTi₃S₈) and a = 0.99716(1) nm (Cu₂NiTi₃S₈). The atomic parameters were calculated in anisotropic approximation (R_I = 0.0456 and R_I = 0.0520 for Cu₂MnTi₃S₈ and Cu₂NiTi₃S₈, respectively).     

New Arsenide Yb2Cu4As3: Crystal Structure and Electronic State of Ytterbium

A new arsenide of composition Yb₂Cu₄As₃ was prepared by elemental synthesis, and its structure was determined by x-ray diffraction (Rietveld powder-diffraction analysis, 118 independent reflections, R _I = 0.064, R _p = 0.097): Hf₂Co₄P₃ type, sp. gr. P 2m, a = 1.33072(3) nm, c = 0.40091(1) nm. Magnetic susceptibility measurements and EXAFS data indicate that Yb₂Cu₄As₃ contains roughly equal amounts of Yb²⁺ (4f ¹⁴ configuration) and Yb³⁺ (4f ¹³).     

Tailoring Chiroptical Activity of Iron Disulfide Quantum Dot Hydrogels with Circularly Polarized Light

Chiral inorganic nanomaterials have recently attracted significant attention because of their many important applications, such as in asymmetric catalysis and chiral sensing. Here, chiral iron disulfide quantum dots (FeS₂ QDs) are synthesized via chirality transfer using l/d ‐cysteine (Cys) as chiral ligands. The chiral FeS₂ QDs are coassembled with two gelators to produce a cogel (l ‐ or d ‐[Gel+FeS₂]) with a g‐factor value of ±0.06. Interestingly, the cogels display intense circularly polarized luminescence. More significantly, the degree of twisting (twist pitch) and the diameter of the cogels can be markedly regulated by illumination with circularly polarized light (CPL) in the ranges of 120–213 and 37–65 nm, respectively, which is caused by the CPL‐induced electron transfer. This research opens the way for the design of chiroptical devices with a wide range of functions and applications.     

Cu7.2S4 nanosheets decorated on the {3 3 2} high index facets of Cu2O with controllable oxygen defects and enhanced photocatalytic activity

The heterostructure of Cu_7.2S₄ nanosheets/trisoctahedron Cu₂O were successfully constructed on the {3 3 2} high-index facets of Cu₂O. The results show that oxygen defects amount of the Cu_7.2S₄/Cu₂O samples are closely related to the thickness of Cu_7.2S₄ nanosheets. Compared with the unmodified cuprous oxide and the Cu_7.2S₄/Cu₂O modified with thick Cu_7.2S₄ nanosheets, the Cu_7.2S₄/Cu₂O grafted with 10 nm thickness of Cu_7.2S₄ show higher oxygen defects content and photocatalytic performance for MO decoloration. UV–VIS DRS and PL detection show that the Cu_7.2S₄ nanosheets grafting on Cu₂O with high-index facets accelerates the charge carrier separation, which results in an elevated degradation properties for MO.     

Chiral Octahydro‐Binaphthol Compound‐Based Thermally Activated Delayed Fluorescence Materials for Circularly Polarized Electroluminescence with Superior EQE of 32.6% and Extremely Low Efficiency Roll‐Off

Circularly polarized organic light‐emitting diodes (CP‐OLEDs) are particularly favorable for the direct generation of CP light, and they demonstrate a promising application in 3D display. However, up to now, such CP devices have suffered from low brightness, insufficient efficiency, and serious efficiency roll‐off. In this study, a pair of octahydro‐binaphthol ( OBN )‐based chiral emitting enantiomers, (R/S)‐OBN‐Cz , are developed by ingeniously merging a chiral source and a luminophore skeleton. These chirality–acceptor–donor (C–A–D)‐type and rod‐like compounds concurrently generate thermally activated delayed fluorescence with a small ΔE_ST of 0.037 eV, as well as a high photoluminescence quantum yield of 92% and intense circularly polarized photoluminescence with dissymmetry factors (|g_PL|) of ≈2.0 × 10^?3 in thin films. The CP‐OLEDs based on (R/S)‐OBN‐Cz enantiomers not only display obvious circularly polarized electroluminescence signals with a |g_EL| of ≈2.0 × 10^?3, but also exhibit superior efficiencies with maximum external quantum efficiency (EQE_max) up to 32.6% and extremely low efficiency roll‐off with an EQE of 30.6% at 5000 cd m^?2, which are the best performances among the reported CP devices to date.     

Centimeter-Sized Piezoelectric Single Crystal of Chiral Bismuth-Based Hybrid Halide with Superior Electrostrictive Coefficient

The lead-free hybrid perovskite piezoelectrics possess advantages of easy processing, light weight, and low-toxicity over inorganic ceramics. However, the lack of understanding in structure–property relationships hinders exploration of new molecular piezoelectric crystals with excellent performances. Herein, by introducing chiral α-phenylethylammonium (α-PEA⁺) cations into bismuth-based hybrid halides, centimeter-sized (R-α-PEA)₄Bi₂I₁₀ and (S-α-PEA)₄Bi₂I₁₀ single crystals with a superior piezoelectric voltage coefficient g₂₂ of 309 mV m N⁻¹, are obtained. Structural rigidity in crystals leads to a remarkable electrostrictive coefficient Q₂₂ of 25.8 m⁴ C⁻², nearly 20 times higher than that of poly(vinylidene fluoride) (PVDF), which is beneficial to improve piezoelectricity with the synergistic effect of chirality. Moreover, the as-grown crystals show outstanding phase stability from 173 K to ≈470 K. This work suggests a design strategy based on rigidity and chirality to exploit novel piezoelectrics among hybrid metal halides.     

Enantiomeric MOF Crystals Using Helical Channels as Palettes with Bright White Circularly Polarized Luminescence

The host–guest chemistry of metal–organic frameworks (MOFs) has enabled the derivation of numerous new functionalities. However, intrinsically chiral MOFs (CMOFs) with helical channels have not been used to realize crystalline circularly polarized luminescence (CPL) materials. Herein, enantiomeric pairs of MOF crystals are reported, where achiral fluorophores adhere to the inner surface of helical channels via biology-like H-bonds and hence inherit the helicity of the host MOFs, eventually amplifying the luminescence dissymmetry factor (g_lum) of the host l /d -CMOF (±1.50 × 10⁻³) to a maximum of ±0.0115 for the composite l /d -CMOF⊃fluorophores. l /d -CMOF⊃fluorophores in pairs generate bright color-tunable CPL and almost ideal white CPL (0.33, 0.32) with a record-high photoluminescence quantum yield of ≈30%, which are further assembled into a white circularly polarized light-emitting diode. The present strategy opens a new avenue for propagating the chirality of MOFs to realize universal chiroptical materials.     

H/F‐Substitution‐Induced Homochirality for Designing High‐Tc Molecular Perovskite Ferroelectrics

A ferroelectric with a high phase‐transition temperature (T_c) is an indispensable condition for practical applications. Over the past decades, both strain engineering and the isotope effect have been found to effectively improve the T_c within ferroelectric material systems. However, the former strategy seems to prefer working in inorganic ferroelectric thin films, while the latter is also limited to some certain systems, such as hydrogen‐bonded ferroelectrics. It is noted that a mono‐fluorinated molecule is geometrically very similar to its parent molecule and the substitution of H by an F atom can introduce a chiral center on the molecule to template or stabilize polar structures. Significantly, the barrier of rotation of the fluorinated organic molecules is raised, resulting in a remarkable increase in T_c. Herein, by applying the molecular design strategy of H/F substitution to the organic–inorganic perovskite ferroelectric (pyrrolidinium)CdCl₃ with a low T_c of 240 K, two high‐T_c chiral perovskite ferroelectrics, (R)‐ and (S)‐3‐F‐(pyrrolidinium)CdCl₃ are successfully synthesized, for which the T_c reaches 303 K. The significant enhancement of 63 K in T_c extends the ferroelectric working temperature range to room temperature. This finding provides a new effective way to regulate the T_c in ferroelectrics and to design high‐T_c molecular ferroelectrics.     

Synthesis of Thermally Stable and Highly Luminescent Cs5Cu3Cl6I2 Nanocrystals with Nonlinear Optical Response

Low-dimensional Cu(I)-based metal halide materials are gaining attention due to their low toxicity, high stability and unique luminescence mechanism, which is mediated by self-trapped excitons (STEs). Among them, Cs₅Cu₃Cl₆I₂, which emits blue light, is a promising candidate for applications as a next-generation blue-emitting material. In this article, an optimized colloidal process to synthesize uniform Cs₅Cu₃Cl₆I₂ nanocrystals (NCs) with a superior quantum yield (QY) is proposed. In addition, precise control of the synthesis parameters, enabling anisotropic growth and emission wavelength shifting is demonstrated. The synthesized Cs₅Cu₃Cl₆I₂ NCs have an excellent photoluminescence (PL) retention rate, even at high temperature, and exhibit high stability over multiple heating–cooling cycles under ambient conditions. Moreover, under 850-nm femtosecond laser irradiation, the NCs exhibit three-photon absorption (3PA)-induced PL, highlighting the possibility of utilizing their nonlinear optical properties. Such thermally stable and highly luminescent Cs₅Cu₃Cl₆I₂ NCs with nonlinear optical properties overcome the limitations of conventional blue-emitting nanomaterials. These findings provide insights into the mechanism of the colloidal synthesis of Cs₅Cu₃Cl₆I₂ NCs and a foundation for further research.     

Cu7S4 Nanosuperlattices with Greatly Enhanced Photothermal Efficiency

According to the simulation, the self‐assembly of Cu₇S₄ nanocrystals would enhance the photothermal conversion efficiency (PCE) because of the localized surface plasmon resonance effects, which is highly desirable for photothermal therapy (PTT). A new strategy to synthesize Cu₇S₄ nanosuperlattices with greatly enhanced PCE up to 65.7% under irradiation of 808 nm near infrared light is reported here. By tuning the surface properties of Cu₇S₄ nanocrystals during the synthesis via thermolysis of a new single precursor, dispersed nanoparticles (NPs), rod‐like alignments, and nanosuperlattices are obtained, respectively. To explore their PTT applications, these hydrophobic nanostructures are transferred into water by coating with home‐made amphiphilic polymer while maintaining their original structures. Under identical conditions, the PCE are 48.62% and 56.32% for dispersed NPs and rod‐like alignments, respectively. As expected, when the nanoparticles are self‐assembled into nanosuperlattices, the PCE is greatly enhanced up to 65.7%. This strong PCE, along with their excellent photothermal stability and good biocompatibility, renders these nanosuperlattices good candidates as PTT agents. In vitro photothermal ablation performances have undoubtedly proved the excellent PCE of our Cu₇S₄ nanosuperlattices. This research offers a versatile and effective solution to get PTT agents with high photothermal efficiency.     

Structural and optical properties of Cu2SnS3 and Cu3SnS4 thin films by successive ionic layer adsorption and reaction

Thin films of Cu₂SnS₃ and Cu₃SnS₄ were obtained by sulfurizing (Cu, Sn)S structured precursors prepared by successive ionic layer absorption and reaction method. The results of energy dispersive spectroscopy (EDS) indicate that some loss in Sn with increasing sulfurization temperature. For the sulfurization temperatures of 380, 400 and 500 °C, tetragonal (I-42m) Cu₂SnS₃, cubic (F-43m) Cu₂SnS₃ and tetragonal (I-42m) Cu₃SnS₄ were formed, respectively. The combination of X-ray diffraction (XRD) results and Raman spectroscopy reveals that there are small Cu_2?x S phase existing in the CTS thin films (400 and 500 °C). Scanning electron microscopy was used to study the morphology of the layers. The ternary compounds present a high optical absorption coefficient (>10⁴ cm^?1). The band gap energy (E _g ) of the CTS thin films is estimated by reflection spectroscopy. The ternary compounds present a high optical absorption coefficient (>10⁴ cm^?1). The estimated band gap energy (E _g ) is 1.05 eV for tetragonal (I-42m) Cu₂SnS₃, 1.19 eV for cubic (F-43m) Cu₂SnS₃, and 1.22 eV for tetragonal (I-42m) Cu₃SnS₄.     

Electrical conduction in some important copper based superionic solids

Measurement of the thermoelectric power (S) and electrical conductivity () of six superionic solids namely CuI, CuPb₃Br₇, Cu₂HgI₄, Cu₃CdI₅, Cu₃RbCl₄, Cu₇(C₆H₁₂NH₃)Br₈ and Cu₁₆Rb₄I₇Cl₁₃ are reported from 300 K to nearly the melting point of each material. The log T andS againstT ^–1 plots are linear in some temperature ranges with different slopes. For each material they show two distinct regions: one corresponding to superionic (SP) and the other to normal phase (NP). In the superionic phase, Cu⁺ ions are the main entity of charge carrier and an extended lattice gas model explains the transport mechanism fairly well. On the higher temperature side of SP, the other cation in the material starts contributing significantly to. In the normal phase the conduction is mainly due to Frenkel defects (Cu⁺ ions at interstitial sites). The enthalpy for migration and heat of transport of these defects has also been evaluated for CuI, CuPb₃Br₇, Cu₂HgI₄ and Cu₃CdI₅. The formation energy of defects has also been calculated for CuI and Cu₃CdI₅. Normal phase has not been obtained in Cu₃RbCl₄, Cu₇(C₆H₁₂NCH₃)Br₈ and Cu₁₆Rb₄I₇Cl₁₃ as their phase transition temperatures lie below room temperature.     

Thin film preparation and characterization of wide band gap Cu3TaQ4 (Q = S or Se) p-type semiconductors

The structural, optical, and electronic properties of thin films of a family of wide band gap (E_g > 2.3 eV) p-type semiconductors Cu₃TaQ₄ (Q = S or Se) are presented. Thin films prepared by pulsed laser deposition of ceramic Cu₃TaQ₄ targets and ex-situ annealing of the as-deposited films in chalcogenide vapor exhibit mixed polycrystalline/[100]-directed growth on amorphous SiO₂ substrates and strong (100) preferential orientation on single-crystal yttria-stabilized zirconia substrates. Cu₃TaS₄ (E_g = 2.70 eV) thin films are transparent over the entire visible spectrum while Cu₃TaSe₄ (E_g = 2.35 eV) thin films show some absorption in the blue. Thin film solid solutions of Cu₃TaSe_4 − xS_x and Cu₃TaSe_4 − xTe_x can be prepared by annealing Cu₃TaSe₄ films in a mixed chalcogenide vapor. Powders and thin films of Cu₃TaS₄ exhibit visible photoluminescence when illuminated by UV light.     

Photoluminescence of Rare-Earth-Doped Ca4Ga2S7

The photoluminescence of Ca₄Ga₂S₇crystals activated with Nd³⁺, Ce³⁺, Pr³⁺, and Tb³⁺was investigated between 77 and 300 K. The spectra of all the crystals studied show an emission band at 543 nm, which is due to the Nd³⁺ G _7/2 I _9/2transition. There is efficient nonradiative energy transfer from Ce³⁺, Pr³⁺, and Tb³⁺to Nd³⁺.     

Growth of silver nano-particle embedded in tellurite glass: Interaction between localized surface plasmon resonance and Er ions

In this paper we show a systematic study of the growth of silver nano-particles (NPs) embedded in an Erbium-doped tellurite glass with annealing time, aiming to a photoluminescence enhancement. The results indicate an improved or quenching of the photoluminescence due to an energy transfer mechanism in the coupling between NP’s electric dipoles and Er⁺³ transitions (⁴S_3/2 → ⁴I_15/2, ⁴F_9/2 → ⁴I_15/2 and ⁴I_13/2 → ⁴I_15/2).     

Synthesis and crystal structures of a new (2,3-(CH3)2C6H3NH3)H2XO4 (X=P,As)

The aim of encapsulation of 2,3-dimethylanilinium cation in (H₂XO₄)_n polymeric anion chains is to build acentric frameworks that are efficient for non-linear optical (NLO) applications. The synthesis and structures of two new inorganic–organic NLO crystals with general formula (2,3-(CH₃)₂C₆H₃NH₃)H₂XO₄ (X=P, As) are reported. The magnitude of their second harmonic generations (SHG) responses was found to be between the KDP and urea. They crystallize with monoclinic unit-cells and are isotopic. We have determined the structure of phosphoric salt. The following unit-cell parameters were found: a=8.866(3) Å, b=5.909(6) Å, c=10.644(5) Å, β=112.44(1)°, V=515.5(5) Å³ and D_X=1.412 g cm⁻³. The space group is P2₁ with Z=2. The structure was refined with R=0.041 (R_w=0.057) for 1652 reflections with I≥3σ(I). It exhibits infinite (H₂PO₄)_nⁿ⁻ chains. The organic groups (2,3-(CH₃)₂C₆H₃NH₃)⁺ are anchored between adjacent polyanions through multiple hydrogen bonds. Chemical preparation, crystal structure, calorimetric and spectroscopic investigation are described.     

Plasmon Enhanced Direct Bandgap Emissions in Cu7S4@Au2S@Au Nanorings

Nanostructured copper sulfides, promising earth‐abundant p‐type semiconductors, have found applications in a wide range of fields due to their versatility, tunable low bandgap, and environmental sustainability. The synthesis of hexagonal Cu₇S₄@Au₂S@Au nanorings exhibiting plasmon enhanced emissions at the direct bandgap is reported. The synthesized Cu₇S₄@Au₂S@Au nanorings show greatly enhanced absorption and emission by local plasmons compared to pure copper sulfide nanoparticles.     

Zur kenntnis von Na2Cu4S3 und KCu3Te2

The crystal structures of the new compounds Na₂Cu₄S₃ and KCu₃Te₂ have been solved. Na₂Cu₄S₃ crystallizes in the K₂Ag₄S₃ structure (space group: C2/m, a = 1563(3) pm, b = 386(2) pm, c = 1033(2) pm, β = 107.6^o, N = 4), KCu₃Te₂ in the CsAg₃S₂ structure (space group: C2/m, a = 1645.3(9) pm, b = 429.4(4) pm, c = 866.1(6) pm, β = 111.86^o, N = 4).