Photoluminescence of Eu2+, Ce3+ and Tb3+ in a new potassium barium phosphate K2Ba3(P2O7)2 host lattice

The Eu2+, Ce3+, Tb3+ and Ce3+-Tb3+ doped ternary metal diphosphate K2Ba3(P2O7)2 is prepared using high temperature solid state synthesis. K2Ba3(P2O7)2:Eu2+ shows a deep blue emission (λmax = 405 nm) when it is excited by UV lights. The broad peak at 405 nm can be decomposed to two Gaussian curves with maxima at 405 and 440 nm which can be attributed to the presence of two crystallographically different Eu2+ sites in the crystal structure. The emission spectrum of K2Ba3(P2O7)2:Ce3+ is dependent of the excitation wavelength that also results from the two crystallographically different Ce3+ sites. The emission spectrum of K2Ba3(P2O7)2:Tb3+ shows the 5D3 and 5D4 emission lines. The f-d spin-allowed and spin-forbidden transitions in Tb3+ in K2Ba3(P2O7)2 are at about 225 and 250 nm, respectively. For the (Ce3+, Tb3+) co-doped K2Ba3(P2O7)2 system, the energy transfer from Ce3+ to Tb3+ is observed.