1D All-Inorganic Metal Halide Rb2AgX3 (X = Cl, Br): Pb-Free Scintillator Materials for Ionising Radiation Detection

Abstract

Rb-based metal halide materials possess large attenuation coefficients and bright luminescence making them suitable as scintillators for X-ray detection. Here, we present the first report of an optimised anti-solvent synthesis route to gram quantities of phase-pure Rb2AgX3, (X = Cl, Br) metal halides, which show broadband emission centred at 585 nm and 514 nm, respectively. These metal halides report fast radiative recombination with typical decay times of sub-10 ns. Optical and radioluminescence measurements revealed halidespecific emission pathways with Rb2AgCl3 displaying superior emission intensities, whereas Rb2AgBr3 consistently elicited a stronger X-ray induced response. High pressure XRD studies measured bulk crystal moduli indicating that the Rb2AgCl3 crystal structure has a stiffer lattice than the Rb2AgBr3 analogue. Compressing pellets of polycrystalline Rb2AgX3 over a range of pressures (both at room temperature and 70 C) confirmed this lattice stiffness trend and allowed for improvements in material densification and optical clarity at thicknesses of > 250 μm. The X-ray response of these pellets improved with increasing pressure for the bromide analogue underscoring the importance of microstructural control in enhancing scintillation efficiencies.