Application of spectroscopic properties of Eu3+ ion to predict the site symmetry of active ions in AgLaP2O7: Eu3+ phosphors

A suite of AgLa1-xEuxP2O7 (x = 1, 5, 10, 15, 20 and 100%) diphosphates were prepared by solid state reaction at T = 500 degrees C. Powder X-rays diffraction analysis (XRD) reveal that AgLaP2O7 phase doped with 1, 5, 10, 15 and 20% of Eu3+ are isostructural with AgLaP2O7 (Hami et al., 2018 [1]) while AgLaP2O7:100% Eu3+ is isostructural with AgTbP2O7 diphosphate (Rizzi et al., 2019 (2)). A decreasing trend for unit cell parameters of solid solutions with increasing the Eu3+ content have been observed. The Fourier Transform InfraRed (FTIR) spectra are in good agreement with structure type, highlighting the characteristic bands of P2O74- groups attributed to the symmetric and asymmetric stretching of P-O-P bridge. Spectroscopic properties of Eu3+ have been used to probe the local environment of the Eu3+ ion in AgLaP2O7:Eu3+. The number of components observed for the D-5(0) -> F-7(0-4) transitions is consistent with that predicted by group theory calculations for Cs symmetry. The CIE chromaticity coordinates (x, y) for AgLaP2O7: 10, 15 and 20% Eu samples have been calculated.