Large Scale BN-perovskite Nanocomposite Aerogel Scintillator for Thermal Neutron Detection

Achieving Efficient Fast Neutron and Gamma Discrimination in Hydrogen-Rich 2D Halide Perovskite Scintillators

Neutron radiation fields frequently coexist with γ-rays, posing a significant challenge to ensure the accuracy of neutron detection. 2D perovskites have been proved to be the potential fast neutron scintillators due to their structural properties and excellent luminescent performance. Herein, the study reports on the scintillation properties of 2D perovskite phenethylammonium lead bromide ((PEA)2PbBr4) single crystal (SC) induced by different types of radiation and first demonstrate its pulse shape discrimination (PSD) capability in neutron/gamma (n/γ) mixed radiation fields. The research has found that the decay time of (PEA)2PbBr4 SC to heavy charged particles (24.4 ns) is significantly faster than that to γ-rays (39.1 ns). This is because the ionization density of heavy charged particles is 2-3 orders of magnitude higher than that of electrons, resulting in a pronounced second-order quenching effect. The unique characteristic endows it with good discrimination capabilities for α-particles and γ-rays. Furthermore, the study has successfully demonstrated a good n/γ discrimination with a figure of merit (FOM) of 0.86 in Deuterium-Deuterium (D-D) fusion reaction. The research not only advances the application of perovskites in the field of neutron detection, but also provides a new alternative for the development of neutron detection technologies.

Distinct Promotion of PEC Water Oxidation of Ta2O5/α-Fe2O3/Co-Ni PBA via Coupling Ni 3d with O 2p

The development of robust and effective photoanodes is crucial for photoelectrochemical hydrogen production via total water splitting. Herein, the Ta2O5/α-Fe2O3/Co-Ni PBA (TFPB-1) photoanode was constructed by the compositing n-type Ta2O5 and n-type α-Fe2O3 followed by the deposition of p-type Co-Ni PBA. The IPCE of TFPB-1 was increased to 35.4% compared to 13.9% for Ta2O5 owing to the significantly improved light absorption efficiency, carrier separation efficiency and injection efficiency. The TFPB-1 achieved a current density of 2.78 mA cm-2 at 1.23 V (vs RHE), which was around 18.5 times that of Ta2O5. The OER overpotential over TFPB-1 was reduced to 0.59 V compared to 1.13 V for Ta2O5, resulting in a substantial reduction in the free energy of PEC water oxidation over TFPB-1. As a result, TFPB-1 exhibited remarkably enhanced photoelectrocatalytic activity for oxygen evolution through water oxidation.

Transparent composites for efficient neutron detection

Transparent, inorganic composite materials are of broad interest, from structural components in astronomical telescopes and mirror supports to solid-state lasers, smart window devices, and gravitational wave detectors. Despite great progress in material synthesis, it remains a standing challenge to fabricate such transparent glass composites with high crystallinity (HC-TGC). Here, we demonstrate the co-solidification of a mixture of melts with a stark contrast in crystallization habit as an approach for preparing HC-TGC materials. The melts used in this approach are selected so that glass formation and crystal precipitation occur simultaneously and synergistically, avoiding the formation of interfacial cracks, residual pores, and delamination effects. Using this method, various unusual hybridized HC-TGC materials such as oxychloride, oxybromide, and oxyiodide composite systems were fabricated in dense, bulk shapes. These materials exhibit intriguing optical properties and neutron response-ability. Using such HC-TGC materials, we develop a neutron detector and demonstrate the application for efficient neutron monitoring and even single neutron detection. We expect that these findings may help to bring about a generation of fully inorganic, transparent composites with synergistic combinations of conventionally incompatible materials.

High-yield synthesis of hydroxylated boron nitride nanosheets and their utilization in thermally conductive polymeric nanocomposites

Hexagonal boron nitride nanosheets (BNNSs) possess remarkable potential for various applications due to their unprecedented properties. However, the scalable production of BNNSs with both expansive surface and high solubility continues to present a significant challenge. Herein, we propose an innovative and efficient two-step method for manufacturing hydroxyl-functionalized BNNSs (OH-BNNSs). Initially, hydroxyl groups are covalently attached to bulk hexagonal boron nitride (h-BN) surfaces through H2O2 treatment. Then, the hydroxyl-functionalized h-BN undergoes exfoliation on account of a sudden increase in interlayer gas pressure generated by the vigorous decomposition of H2O2 in alkali solutions, resulting in the creation of OH-BNNSs. This approach produces relatively large flakes with an average dimension of 1.65 μm and a high yield of 45.2%. The resultant OH-BNNSs exhibit remarkable stability and dispersibility in a range of solvents. Their integration into thermoplastic polyurethane (TPU) significantly enhances both thermal conductivity and stability, attributed to the excellent compatibility with the resin matrix. This study represents a significant advancement in the functionalization and exfoliation of h-BN, opening new avenues for its promising applications in polymer composites.

Arising 2D Perovskites for Ionizing Radiation Detection

2D perovskites have greatly improved moisture stability owing to the large organic cations embedded in the inorganic octahedral structure, which also suppresses the ions migration and reduces the dark current. The suppression of ions migration by 2D perovskites effectively suppresses excessive device noise and baseline drift and shows excellent potential in the direct X-ray detection field. In addition, 2D perovskites have gradually emerged with many unique properties, such as anisotropy, tunable bandgap, high photoluminescence quantum yield, and wide range exciton binding energy, which continuously promote the development of 2D perovskites in ionizing radiation detection. This review aims to systematically summarize the advances and progress of 2D halide perovskite semiconductor and scintillator ionizing radiation detectors, including reported alpha (α) particle, beta (β) particle, neutron, X-ray, and gamma (γ) ray detection. The unique structural features of 2D perovskites and their advantages in X-ray detection are discussed. Development directions are also proposed to overcome the limitations of 2D halide perovskite radiation detectors.

Capillary Manganese Halide Needle-Like Array Scintillator with Isolated Light Crosstalk for Micro-X-Ray Imaging

The exacerbation of inherent light scattering with increasing scintillator thickness poses a major challenge for balancing the thickness-dependent spatial resolution and scintillation brightness in X-ray imaging scintillators. Herein, a thick pixelated needle-like array scintillator capable of micrometer resolution is fabricated via waveguide structure engineering. Specifically, this involves integrating a straightforward low-temperature melting process of manganese halide with an aluminum-clad capillary template. In this waveguide structure, the oriented scintillation photons propagate along the well-aligned scintillator and are confined within individual pixels by the aluminum reflective cladding, as substantiated from the comprehensive analysis including laser diffraction experiments. Consequently, thanks to isolated light-crosstalk channels and robust light output due to increased thickness, ultrahigh spatial resolutions of 60.8 and 51.7 lp mm-1 at a modulation transfer function (MTF) of 0.2 are achieved on 0.5 mm and even 1 mm thick scintillators, respectively, which both exceed the pore diameter of the capillary arrays' template (Φ = 10 µm). As far as it is known, these micrometer resolutions are among the highest reported metal halide scintillators and are never demonstrated on such thick scintillators. Here an avenue is presented to the demand for thick scintillators in high-resolution X-ray imaging across diverse scientific and practical fields.