Subresonantly excited Nd3+ fluorescence in LiLa1−xNdxP4O12 nanocrystals

Nd3+ fluorescence of LiNdP4O12 nanocrystals was observed upon subresonant excitation with the 1064 nm wavelength of LD laser at room temperature. It was found that the 4F3/2 fluorescence was temperature dependent. The distribution of intensities between the respective Stark sublevels of 4F3/2(R1, R2) → 4I9/2(Z1–5) transition band was substantially different in comparison to the resonant excitation with the 514 nm line of argon laser. A mechanism of subresonant Nd3+ fluorescence was investigated. It was concluded that it is associated with a high thermal population of 4I11/2 term stimulated by cooperative Nd–Nd interion interaction.