Super-Tunable LaSi₃N₅ Structure Type: Insights into the Structure and Luminescence of SrSi₂PN₅:Eu²⁺

In this study, the structural and luminescence properties of SrSi2PN5:Eu2+ and its analogues within the LaSi3N5 structure type are investigated by using a variety of analytical techniques, including X-ray diffraction (XRD), 31P solid-state NMR, and powder neutron diffraction. We are exploring the challenges of chemical similarity and low X-ray contrast between the key elements to extend our analytical capabilities by powder neutron diffraction (PND) for (Si,P)–N networks. In principle, PND shows greater differences in scattering contrasts for O/N and Si/P, although it does not surpass standard powder XRD in elemental discrimination of Si/P within the network. The Eu2+ doping of SrSi2PN5 demonstrates the potential for tunable optical applications within the group of LaSi3N5 analogous materials. Our results contribute to the understanding of the structural diversity and luminescence mechanisms of nitridosilicate phosphates and emphasize the importance of a comprehensive analytical approach in materials science, with implications for the future development of optoelectronic devices.