Figure 2
From: Morphological evolution of upconversion nanoparticles and their biomedical signal generation
XRD patterns of the as-prepared UCNP: (a) 180 °C, (b) 190 °C, (c) 200 °C, (d) 210 °C. Particles corresponding to both α-NaYF4, PDF 00-027-0688 and β-NaYF4, PDF 00-016-0334 are observed. (e) Schematic illustration of the phase transformation of the UCNP with increasing HR time.
