Rare-earth-doped SiO2-CaF2 glass ceramic nano-particle with upconversion properties

Rare-earth-doped upconversion nano-phosphor shows new possibilities in the field of bioimaging because of its unique properties like higher penetration depth, low signal to noise ratio (SNR), good photo stability, and zero auto fluorescence. The oxyfluoride glass system is the combination of both fluoride and oxide where fluoride host offers high optical transparency due to low phonon energy and oxide network offers high physical stability. Thus, in the present work, an attempt has been made to synthesize 1 mol% Er3+ doped SiO2-CaF2 glass ceramic nano-particles through sol-gel route. The synthesized glass ceramic particles were heat treated at 4 different temperatures starting from 600 degrees C to 900 degrees C.The X-ray diffraction (XRD) analysis and Transmission electron microscopy (TEM) analysis confirmed the formation of CaF2 nano-crystals in the matrix which is 20-30 nm in size. The vibrational spectroscopic analysis of the glass ceramics sample has been investigated by Fourier transform infrared (FTIR) spectroscopy. The UV-Visible-NIR spectroscopy analysis was carried out to analyze the absorption intensity in the near infrared region. Upon 980 nm excitation, the sample shows red emission corresponds to (F9/2I15/2)-F-4-I-4 energy level transition. The prepared nano-particles showed excellent biocompatibility when tasted on MG-63 osteoblast cells.