For Na 7 Eu 2 (P 2 O 7 ) 2 (P 3 O 10 ), we followed the procedure used for its only reported isostructural compound, Na 7 Y 2 (P 2 O 7 ) 2 (P 3 O 10 ). The resulting product also contained EuPO 4 , along with an unidentifiable phase(s). The XRD pattern is in the Supporting Information along with synthesis attempt details. EuPO 4 again appears to be more energetically favorable than the predicted alkali-europium-phosphate compound.