Jian-Rong Li

Conventional inorganic scintillators suffer from severe thermal quenching at elevated temperatures, severely limiting their application in high‐temperature radiation detection. Herein, a three‐dimensional (3D) negative thermal expansion (NTE) scintillator, Lu ₂ (WO ₄ ) ₃ :Eu ³⁺ (LWO:Eu), is reported, which exhibits continuous radioluminescence (RL) thermal enhancement upon X‐ray excitation from 313 to 573 K. Unlike positive thermal expansion materials, LWO:Eu contracts volumetrically with an exceptionally large NTE coefficient (α _v = −24.22 × 10 ⁻⁶ /K), uniformly shortening the atomic distances between heavy atoms (W) and luminescent centers (Eu ³⁺ ). This unique 3D NTE behavior fundamentally boosts energy transfer efficiency from WO ₄ ²⁻ to Eu ³⁺ at high temperatures, as further evidenced by in situ temperature‐dependent XRD and Raman analyses. Consequently, LWO:Eu achieves a record‐high light yield of 64839 photons/MeV at 573 K and an ultralow detection limit of 38.2 nGy/s, with a 4.5‐fold thermally enhanced red emission ( ⁵ D ₀ → ⁷ F ₂ ). A room‐temperature X‐ray imaging resolution of 22 l p/mm and successful scintillation imaging at 473 K is demonstrated, far outperforming commercial scintillators such as BGO, CsI:Tl, and LYSO:Ce. This work establishes a new paradigm for thermally enhanced RL materials based on 3D NTE, offering great promise for extreme‐environment applications including nuclear reactor monitoring, oil well logging, aerospace exploration, and high‐energy physics.

Accurate detection of trace water is essential for ensuring the quality control of moisture-sensitive solvents, chemical processes, and advanced materials. Herein we present a water-triggered structural transformation in hybrid manganese bromide of MnBr2(C3H7NO) for visual trace-water detection. This compound was synthesized by using pure water as a solvent with high yield. One-dimensional (1D) MnBr2(C3H7NO) exhibits bright red photoluminescence with a quantum yield of 20.39%. Upon exposure to trace water, MnBr2(C3H7NO) undergoes rapid single-crystal-to-single-crystal structural transformation from a 1D chain to a 0D nonluminescent hydrated structure of MnBr2(C3H7NO)2(H2O)2, resulting in fluorescence quenching. The fluorescence response is notably nonlinear, with a low limit of detection of 87.9 ppm and signal amplification over a narrow concentration window (∼100 ppm), enabling visual detection of trace water across various organic solvents. Notably, this process is partially reversible upon mild thermal treatment, allowing recycled use. This work demonstrates a sustainable platform for instrument-free water sensing and highlights dimensionality transformation as an effective strategy for luminescent sensing materials.

In this study, we successfully synthesized large-sized single crystals of a two-dimensional rare-earth double perovskite, (TEA)KNd(NO3)5(H2O) (1). Single-crystal diffraction confirms coordinated water molecules construct an intralayer hydrogen-bond network, lowering lattice symmetry, strengthening intermolecular interactions, inhibiting phase transitions and boosting in-plane charge transport to favor charge collection and low-bias X-ray response under low dose rates. UV–vis diffuse reflectance measurements and DFT calculations validate its wide-bandgap characteristic; band-edge states mainly originate from nitrate O-2p orbitals, and coordinated water indirectly tunes electronic properties via structural modulation. Notably, 1 exhibits outstanding X-ray detection capability. Under a dose rate range of 30–402 nGy·s–1 and a bias of 5 V, the device achieved a sensitivity of 533.409 μC·Gyair–1·cm–2 and a low detection limit of 1.353 nGy·s–1, alongside excellent operational stability. These results highlight the critical role of coordinated water molecules in suppressing phase transitions and achieving high-performance X-ray detection, providing insights for the development of environmentally friendly, high-performance X-ray detectors.

Organic-inorganic hybrid metal halides (OIHMHs), whose structures and optical properties can be tuned, have attracted increasing attention. Herein, we report a hybrid manganese chloride prepared by ionothermal synthesis using the hydroxyl-functionalized ionic liquid 1-(2-hydroxyethyl)-3-methylimidazolium chloride ([HOEtMIm]Cl) as both solvent and reactant. Unlike conventional ionic liquids that function primarily as solvents or structure-directing agents, [HOEtMIm]Cl acts as organic ligand and halogen source to coordinate with Mn2+, generating a one-dimensional hybrid manganese chloride chain of MnCl3(HOEtMIm). MnCl3(HOEtMIm) displays high thermal stability and red emission associated with the spin-forbidden 4T1 → 6A1 transition of Mn2+. These results show that functionalized ionic liquids can act as programmable coordination modules in hybrid metal halides, providing a strategy to tune metal coordination environments and luminescent properties.

Organic–inorganic hybrid iodoplumbates have garnered attention due to their diverse structures and optoelectronic properties, showing potential for applications in photoelectric devices and energy conversion. Conventional synthesis methods often involve toxic or volatile organic solvents. In this study, two layered Pb-M (M = Cu, Ag) heterometallic iodoplumbates were successfully synthesized by ionothermal method using iodine-containing ionic liquid as solvent and structure-directing agent, namely (Bmim)(P4442)CuPb6I15 (1) and (Bmim)4/3Ag2/3Pb2I6 (2). Structural analyses reveal that compound 1 features a two-dimensional anionic layer constructed from interconnected [CuI4] tetrahedra and [PbI6] octahedra, exhibiting a unique hexagonal channel architecture. In contrast, compound 2 displays a zigzag layered structure composed of distorted [PbI6] octahedra and partially occupied Ag sites (occupancy = 0.667), which generate an average [AgI4]-based dimeric motif within the inorganic framework. SEM and XPS analyses further confirmed that the heterometallic ions in both compounds are uniformly distributed within the crystal frameworks and exist as Cu+ and Ag+, respectively. Both compounds exhibit good photocurrent response and stability, with the photocurrent density of compound 1 being superior to most reported iodoplumbate complexes. Theoretical calculations revealed its electronic structure and band characteristics. This work not only expands the application of ionic liquids in the synthesis of functional materials, but also provides new insights for designing promising two-dimensional optoelectronic materials.

Stimuli-responsive organic–inorganic hybrid metal halides, capable of undergoing reversible physical property changes under external stimuli, hold potential application value in fields such as smart electronic devices and sensors. This paper reports a novel lead-free Sb(III)-based hybrid metal halide, (C5H5NO)2SbCl5 (1), which consists of protonated 3-hydroxypyridine cations and discrete [SbCl5]2- anions, and can be obtained as centimeter-sized transparent single crystals via a simple solvent evaporation method. Variable-temperature structural analysis indicates that the protonated 3-hydroxypyridine cation exhibits a dynamically disordered state at room temperature but tends toward order at low temperatures. Corresponding to this structural evolution, the compound exhibits a distinct step-like dielectric anomaly of the relaxor type within the temperature range of 120-250 K. This dielectric behavior is primarily attributed to the temperature-induced dynamic transition between order and disorder within the protonated 3-hydroxypyridine cations. In addition, UV-vis diffuse reflectance spectroscopy and DFT calculations reveal the semiconducting characteristics of 1, with the band-edge electronic states mainly associated with the inorganic [SbCl5]2- units. This work expands the scope of applications for hydroxyl-modified aromatic heterocyclic cations in hybrid metal halide dielectric materials and provides a valuable reference for the rational design of multifunctional molecular crystals that simultaneously possess dielectric switching.

A 3D hybrid rare-earth double perovskite ( R M3HQ) ₄ K ₂ [Nd(NO ₃ ) ₆ ] ₂ is reported, with a record-high ferroelectric phase transition temperature (∼410 K) for such a system, and simultaneous switchable ferroelectricity and reversible ferroelasticity.

M^IRE^III-based nitrate-bridged double perovskite-type hybrid materials are an emerging class of multifunctional materials that exhibit intriguing physical properties. While the synthesis and structural phase transitions of these compounds, including (TMA)₂NaPr(NO₃)₆ (TMA⁺ = tetramethylammonium cation, 1), have been recently established, their potential in electronic applications remains largely unexplored. Herein, we focus on the functional characterization of 1, which exhibits a reversible phase transition at T_tr = 306 K, dynamic dielectric response, and semiconducting behavior with an indirect band gap of 3.81 eV at 335 nm. Furthermore, 1 exhibits a luminescent property with a fluorescence lifetime of 29.09 ns. More importantly, an X-ray detector fabricated from a single crystal of 1 demonstrates a sensitivity of 27 μC·Gy_air^-1·cm^-2 and a minimum detectable dose rate of 0.038 mGy_air·s^-1 at an ultralow bias of 1 V. This performance surpasses that of commercial amorphous selenium-based direct-type detectors (XR100SDD and BrillianSe). This work not only demonstrates the multifunctionality of 1, including dielectric response, fluorescence, and X-ray response but also opens potential applications for developing novel optoelectronic and sensing devices.