Abstract
This paper introduces an innovative theory for customizing photoluminescence (PL) emission wavelengths in rare earth ion (Eu2+) doped alkaline earth metals (Ca, Mg) silicates, rooted in the entropy of fusion and configurational entropy of congruent and incongruent silicates, respectively, aiming to reveal dynamic deformation of the tetrahedral SiO4 ligand within these materials. Using FactSage, we computationally calculate the fusion entropy of congruent silicates in the CaO-MgO-SiO2 system. Synthesized ternary silicates confirm our theory by highlighting correlations between lower/higher fusion entropy (for congruent) and configurational entropy (for incongruent) silicates, leading to red/blue shifts in PL emission wavelengths. In binary silicate systems, we observe an inverse correlation between PL emission wavelengths and fusion entropy of congruent silicates or pseudo-congruent silicates like MgSiO3, whose solid-liquid decomposition temperature is close to its melting point. Furthermore, the non-ideal liquid phase entropy of incongruent silicates positioned between congruent CaMgSi2O6 (Pyroxene) and congruent Ca2MgSi2O7 (Akermanite) in the MgO-CaO-SiO2 ternary phase diagram comprehensively explains diverse PL emission wavelengths. Beyond its scholarly impact, this work expands perspectives in lighting and photonic research, opening an exciting frontier in entropy-lighting research and enabling predictions of host chemical composition and tunable PL emission wavelengths, particularly relevant to LED technologies.