Properties Design: Prediction and Experimental Validation of the Luminescence Properties of a New Eu II ‐Based Phosphor

A theoretical model that allows to predict, for the first time, the luminescence properties of a new phosphor (BaSnSi 3 O 9 :Eu 2+ ) is presented. The predicted emission wavelength, 488 nm with a 64 nm bandwidth, was confirmed by subsequent experimental work. The method consists in a multi‐electron Hamiltonian parametrized from ab initio calculations. The luminescence properties of other similar compounds (i.e., BaHfSi 3 O 9 :Eu 2+ and BaZrSi 3 O 9 :Eu 2+ ), for which there is already experimental information, were also correctly reproduced.