The monoclinic monazite LaPO₄:Eu³⁺ phosphors were fabricated in NH₄NO₃ flux at 160 °C for 4 h.

The consultant products exhibit almost nearly monodispersity and quasihexagonal and their mean sizes are of 30 nm.

With the enhancement of the temperature the red-shift and spectral broadening of the charge-transfer band (CTB) were observed. The optimal Eu³⁺ concentration is ca. 8 at.%. The higher concentration quenching was observed due to the possible nonradiative energy transfer by electric multipole–multipole interaction.

The relationship between the FL lifetime of ⁵D₀ energy level and Eu³⁺ concentration has been investigated according to Auzel’s model. The fitting results indicates the energy phonon number in the nonradiative relaxation from the lowest energy level of ⁵D₀ and the highest energy level of ⁷F₆ is 7 and the intrinsic lifetime τ₀ of ⁵D₀ energy level is 6.94 ms.