In the quest to understand the origin of photoluminescent efficiency in rare-earth substituted inorganic phosphors, research has shown that materials consisting of ordered, highly rigid crystal structures tend to have the highest quantum yield. A compound’s Debye temperature (ΘD), which can be calculated using ab initio calculations, is an ideal proxy for structural rigidity to identify potentially efficient phosphors. However, as calculations on the substituted host structure require the construction of supercells, making them computationally inaccessible, these calculations are typically conducted on the host structure without the luminescent center. This work evaluates the effect of luminescent center substitution on the host structure’s ΘD to validate the use of ab initio calculations of unsubstituted hosts to predict structural rigidity. Two well-known phosphors, Y3Al5O12:Ce3+ and BaMgAl10O17:Eu2+ were synthesized with different rare-earth concentrations and the ΘD determined through multiple methods: speed of sound measurements, experimental heat capacity measurements, and ab initio calculations. The experimental results show that even upon 10% luminescent center substitution, the ΘD of Y3Al5O12:Ce3+ does not change, whereas the ΘD of BaMgAl10O17:Eu2+ shows a slight (&lt;100 K) change. This work verifies that ΘD, obtained through ab initio calculations of the unsubstituted host structures, can be used to estimate structural rigidity of the substituted hosts and predict phosphor efficiency, thus enabling high-throughput screening of crystal structure databases to direct synthesis of efficient phosphors.

Investigation of the effect of rare-earth substitution on the Debye temperature of YAG:Ce3+ and BAM:Eu2+

255th National Meeting (2018)

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