Confined growth strategy enabling Cs ₂ ZrCl ₆ nanocomposite crystals with adjustable particle size and high-efficiency luminescence for additive manufacturing of composite scintillators

Cs ₂ ZrCl ₆ crystals, as a kind of lead-free metal halide perovskite material, demonstrate great potential in X-ray detection and imaging applications. However, Cs ₂ ZrCl ₆ crystal powders exhibit uncontrollable particle growth behavior and poor suspension stability in solution, severely hindering the uniform assembly of composite scintillators and their X-ray detection capabilities. To address these issues, our work innovatively proposes a confined growth strategy for preparing Cs ₂ ZrCl ₆ nanocomposite crystals with tunable particle sizes and high luminescence efficiency, satisfying the requirements for manufacturing composite scintillators. The core design of confined growth processes involves selecting fumed silica and fumed alumina as nanopore templates, enabling effective regulation over the particle size of Cs ₂ ZrCl ₆ crystals within the range of 13.8-445 nm, thereby preventing the sedimentation of large aggregates that could induce phase separation in the preparation process of composite scintillators. The excitation and emission wavelengths of Cs ₂ ZrCl ₆ nanocomposite crystals are approximately 254 nm and 435 nm, respectively, with a Stokes shift of ∼180 nm, exhibiting a significant characteristic of self-trapped exciton (STE) luminescence. Benefiting from the high efficiency of the STE emission, the decay curves show a single exponential fitting feature, with photoluminescence decay lifetimes centered around 15 µs. Meanwhile, Cs ₂ ZrCl ₆ nanocomposite crystals possess a high radiation absorption cross-section, with a high light yield measured via a relative method based on X-ray excitation spectra reaching up to 72,000 ph·MeV ⁻¹ , demonstrating excellent light output performance. Relying on additive manufacturing technology, Cs ₂ ZrCl ₆ nanocomposite crystals could be fabricated into composite scintillators with uniform component distribution and tailored spatial geometries, which would greatly expand the application scenarios of Cs ₂ ZrCl ₆ crystals.