ABSTRACT
The cubic structure of nanocrystalline ZrO2 co-doped with Er3+,Yb3+ ions was synthesized using the zirconium metal-organic framework (Zr-BTC:Er3+,Yb3+) as a precursor after an annealing process at temperatures ranging from 400 to 1000 °C for 1 h. The morphology characterization confirmed 700 °C as the optimal temperature for calcination. XRD, HRTEM and SAED techniques unambiguously confirmed the formation of a cubic structure of ZrO2. The average grain size of the obtained ZrO2:Er3+,Yb3+ upconversion nanoparticles was estimated at 12 ± 1 nm using Scherrer’s equation, TEM and HRTEM images. Moreover, spectroscopic measurements confirmed the stabilization of Yb3+ and Er3+ ions in the crystal structure of ZrO2, presenting a dominant red emission band at 665 nm and a less intense green band at 550 nm associated with 4F9/2→4I15/2 and 2H11/2, 4S3/2→4I15/2 electronic transitions of Er3+ ions, respectively.