Luminescence and Photochromism in Lanthanide‐Doped Hackmanites

ABSTRACT Hackmanites are a class of materials that exhibit diverse and intriguing optical characteristics, including luminescence and tenebrescence. Doping with other luminescent species would unveil a fresh spectrum of optical properties and potential applications. This project aimed to successfully dope a lithium derivative of hackmanite with highly luminescent lanthanides (Sm 3+ , Eu 3+ , Tb 3+ , and Dy 3+ ) using a doped aluminosilicate precursor, LiAlSiO 4 . Initial structural analysis indicated successful doping with little disruption to the host lattice. Luminescence spectroscopy revealed that the emissive properties of the lanthanide ions were largely suppressed upon incorporation into the sodalite due to the presence of other highly luminescent impurities. However, europium‐doped samples exhibited emission from both Eu 2+ and Eu 3+ , with the former resulting in long‐lasting green persistent luminescence. Room‐temperature persistent luminescence was determined to arise from traps at a depth of 0.3 eV. In contrast, doping with samarium yielded a photochromic response atypical of traditional hackmanites, characterized by absorption extending into the near‐infrared region. Spectroscopic evidence suggested the involvement of Sm 2+ /Sm 3+ redox processes coupled to disulphide photochromic centers in the tenebrescence mechanism. Lanthanide doping provides a versatile route for modifying both the luminescence and photochromic behavior of hackmanites, enabling additional functionalities in lighting applications and UV dosimetry.