Conclusion
K2LnZr(PO4)3 (Ln = Y, La, Gd and Lu) samples show strong
absorption bands in the VUV range. The band range from 130 to
170 nm is due to the absorption of the host lattice, or the PO4
groups, and the band at 170–220 nm is from the O–Zr charge
transfer transition. There are no O2–Sm3+, O2–Dy3+ and O2–
Tm3+ CTBs in the VUV excitation spectra for Sm3+, Dy3+ and Tm3+-
doped samples. And for Eu3+-doped samples, the relatively weak
O2–Eu3+ CTB at about 220 nm is observed. The 4f–5d spin-allowed
and spin forbidden transitions (at 223 and 258 nm) of Tb3+ have
been observed in the Tb3+-doped samples. K2GdZr(PO4)3:Sm3+,
Eu3+, Tb3+ are attractive yellow, red, green-emitting PDP phosphors
because of their high luminescent efficiency, color purity and
chemical stability.