Journal of Materials Chemistry C最新文献

Measuring hydrogen concentrations in solid materials, in situ, at the low parts-per-million or parts-per-billion level is extremely challenging, with such concentrations being at or below detection limits of commonly used spectroscopic, ion beam and nuclear methods. Even if hydrogen is detectable, analyses may suffer from poor spatial resolution, precision and accuracy. Rather than measuring hydrogen directly, indirect methods may provide an alternative. Here, we present a novel technique where the luminescence lifetime of Cr³⁺, present as a contaminant at trace levels (sub-ppm) is used to determine hydrogen concentrations in single crystals of magnesium-doped corundum. The crystals are partially diffused with hydrogen, therefore providing a range of hydrogen concentrations to test the method. While we cannot currently fully quantify the data, we can estimate that hydrogen concentrations on the order of tens of parts-per-billion are readily detected with spatial resolution ∼1 μm. Results from lifetime imaging are corroborated and compared with ultraviolet-visible-near infrared and Fourier transform infrared spectroscopy. Overall, the method can be used to achieve significantly higher spatial resolution than widely used absorption techniques, with increased sensitivity. A further advantage is that the method can be used to resolve hydrogen concentration distributions in three dimensions.

The integration of lanthanide ions (Ln³⁺) into halide double perovskites has emerged as a promising approach to tailor their optical and electronic properties for optoelectronic applications. In this study, an Sb³⁺–Tm³⁺ co-doped Cs₂NaInCl₆ double perovskite was synthesized via a simple hydrothermal method. The prepared Cs₂NaInCl₆:Sb³⁺–Tm³⁺ exhibits a single-crystal octahedral structure and achieves an optimal NIR photoluminescence quantum yield of 20%. The co-doping strategy with Sb³⁺ and Tm³⁺ facilitates energy transfer from Sb³⁺ to Tm³⁺, leading to the appearance of an NIR emission peak at 1220 nm. Temperature-dependent (80 to 300 K) photoluminescence measurements elucidate the excitation and emission mechanisms. Through the deposition of the perovskite on a commercial 365 nm LED chip, a pc-LED was engineered to be capable of producing both visible light and NIR emissions.

This study investigates the effects of field-cycling on the critical electric fields (E_t→PO and E_PO→t) of the field-induced ferroelectric (FFE) effect in atomic layer deposited ZrO₂ thin films, focusing on their reversibility and temperature dependence. High-field cycling decreases these critical fields, whereas subsequent lower-field cycling effectively rejuvenates them, challenging the previous report of their irreversibility. Elevated temperature experiments reveal that higher temperature increases the lower limit of E_t→PO reduction, corroborating the thermodynamic predictions of the Landau–Ginzburg–Devonshire (LGD) theory. The rejuvenation effect is also more pronounced at higher temperatures, further corroborating the LGD theory. This study highlights that these reversible transitions between polar and non-polar phases with high- and low-field cycling are a universal phenomenon in fluorite-structured materials, not limited to ferroelectric materials. These findings provide new insights into the field-cycling and temperature-dependent behavior of FFE thin films.

While stimuli-responsive luminescence of organic–inorganic metal halides has reached maturity, the achievement of self-recovering PL (photoluminescence) switching remains a challenge. Herein, we designed and synthesized a 1D organic–inorganic Mn(II) metal halide (C₈H₉N₂)_n{(MnCl₃(H₂O)·H₂O)}_n (C₈H₉N₂ = 2-methylbenzimidazolium, named compound 1), which shows bright red emission with a quantum yield of 12.9%. The compound 1 crystals exhibit an obviously blue-shifted conversion from red emission (645 nm) to yellow emission (560 nm) as the temperature increases to 410 K. TGA and IR spectra reveal that the emission transition originates from the release of free and coordinated water molecules in the lattice. Remarkably, reversible luminescent conversion was observed after exposure to air for several hours, which contributed to the uptake of water, demonstrating the achievement of self-recovering PL modulation by the absorption of water under normal air. This work provides a novel and feasible design strategy for temperature/water stimuli-responsive sensing technology.

Long afterglow materials with excellent optical properties and stable performance are urgently required, particularly in the fields of anti-counterfeiting and encryption. Nowadays, glass ceramics are promising candidates for afterglow, due to their good ability to capture photons and robust chemical stability. Here, a series of Tb³⁺/Sm³⁺ co-doped gallosilicate glass precursors were prepared via a high-temperature melting method, forming transparent glass ceramics containing LiGa₅O₈ nanocrystals by heat-treatment. The afterglow phenomenon was observed in these samples after turning off UV irradiation, and subsequent investigation showed that, by controlling the concentration of two rare earth ions Tb³⁺ and Sm³⁺, the afterglow could be transitioned from green (LiGa₅O₈:Tb³⁺) to orange (LiGa₅O₈:Sm³⁺) and then to yellow (LiGa₅O₈:Tb³⁺,Sm³⁺). Structural analysis reveals that Tb³⁺ and Sm³⁺ ions have occupied the octahedral sites (Ga sites) in the LiGa₅O₈ anti-spinel structure, which makes them close to intrinsic defects beneficial for the afterglow. Furthermore, the process of energy transfer from Tb³⁺ to Sm³⁺ ions and the sharing of oxygen vacancy defects are importantly outlined in order to elucidate the mechanism behind the multi-color afterglow phenomenon. The tunable afterglow-emitting glass ceramics provide a novel approach for optical anti-counterfeiting and information encryption, thereby enriching the visual diversity of displayed information.

We synthesize and study the charge transfer properties of a oligosilyl coordination polymer formed from zirconium clusters. Although the product lacks long range order, spectroscopic and computational evidence suggest that the metal–ligand bond is formed, and the principle crystallographic reflections closely match those simulated from inter-node spacings matching that of the ligand. The porous polymer allows for the incorporation of guest molecules as demonstrated by the intercalation of 7,7,8,8-tetracyanoquinodimethane (TCNQ). Charge transfer is predicted from DFT and experimentally observed by infrared spectroscopy, solid-state ²⁹Si nuclear magnetic spectroscopy, and voltammetry.

The understanding of colour origins in single-component materials is well established, however comprehending the factors that influence colour in multi-component crystalline phases remains a complex endeavor. This study addresses the challenge of predicting absorption properties in solid-state materials, crucial for designing systems for specific applications. We focused on six multi-component crystals based on violuric acid (VA) and selected L-amino acids, chosen for their chemical and structural diversity. This approach allowed us to explore various factors affecting absorption properties, including co-crystal and salt formation, hydrogen bonding, π–π interactions, amino acid side chain conformations, and solvent inclusion. Techniques such as X-ray diffraction, ¹H NMR spectroscopy, and UV-Vis spectroscopy were employed for detailed analysis of the structure and optical properties of the studied systems. The intermolecular interactions were scrutinized through the topology of electron density, Hirshfeld surface analysis, and the non-covalent interaction (NCI) index. UV-Vis titrations of crystallization solutions were also conducted to determine the binding constants of salts. This comprehensive study aims to enhance our understanding of absorption properties in multi-component materials.