“…Since most rareearth cations (Ce 3+ , Nd 3+ , Eu 3+ , Gd 3+ , Tb 3+ , etc.) possess unfilled d-and f-orbitals, rare-earth phosphates have rich excitation and emission spectrum lines, and are widely used as luminescent materials, 24,25 laser materials 26,27 and scintillators. 28,29 The Ce: LaPO 4 phosphor is widely used in fluorescent tubes and Tb: YPO 4 is reported to be an excellent phosphor for plasma displays.…”