New insights into the role of the doping process on the luminescence properties of MgB4O7:Ce,Li

Abstract

Magnesium tetraborate (MgB4O7) has garnered significant attention in recent years for ionizing radiation dosimetry applications. Despite advances in the material’s performance, the fundamental mechanisms underlying lithium (Li) and cerium (Ce) doping and co-doping remain unclear in the literature. In this study, we comprehensively investigate the role of Li and Ce doping in modulating the luminescence behavior of MgB4O7. To elucidate the underlying mechanisms, we employed an advance multi-technique characterization approach using nuclear reaction analysis, synchrotron-based X-ray nanospectroscopy, X-ray photoelectron spectroscopy (XPS), thermoluminescence (TL) spectrum emission, and photoluminescence (PL) spectroscopy. We have shown that Li remains into the host matrix during the synthesis, being associated with shallow traps such as F2+ center. Also, approximately 50% of Ce4+ is reduced to Ce3+ on the material’s surface, forming complex defect structures involving Ce ions and F-center. Additionally, we present strong evidence that the TL emission around 580 nm originates from F-centers rather than trace Mn elements. Some mechanisms that compete simultaneously with each other have been proposed. Our integrated strategy provides insights into the complex dopant-induced electronic and optical transformations in MgB4O7, offering a detailed understanding of the material’s luminescence characteristics.