Preparation and photoluminescence properties of Er³⁺-doped La₂Zr₂O₇ nanocrystals

(La_1-xEr_x)₂Zr₂O₇ (x = 0, 0.025, 0.05, 0.075, 0.1) nanocrystals have been successfully prepared by the chemical co-precipitation and calcination method, and were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and photoluminescence spectroscopy. The nanocrystals calcined at 800 °C for 5 h exhibit good crystallinity and have a particle size of about 25 nm. The emission band centered at 528 nm is identified as the ²H_11/2 → ⁴I_15/2 transition, the emission bands centered at 550 nm and 562 nm are attributed to the ⁴S_3/2 → ⁴I_15/2 transition, and the emission bands centered at 663 nm and 682 nm are ascribed to the ⁴F_9/2 → ⁴I_15/2 transition. The emission intensity increases with increasing Er³⁺ content, up to a critical concentration between x = 0.025 and x = 0.05, and then decreases with further increasing Er³⁺ concentration.