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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°C to 900°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 4F9/2→4I15/2 energy level transition. The prepared nano-particles showed excellent biocompatibility when tasted on MG-63 osteoblast cells. [ABSTRACT FROM AUTHOR]

The current study delineates the synthesis and characterization of CaF 2 based Oxy-fluoride glass-ceramics with Erbium (1 mol%) and with varying Ytterbium concentration (1 mol% and 5 mol%) doping of fluoride source. The influence of yb3+ concentration on thermal, structural, and luminescence properties were investigated and analyzed through a sol-gel process. The differential thermal analysis (DTA) specified that the glass transition (Tg) temperature decreases with the increase of Yb3+concentration in the prepared glass-ceramics. The microstructural study performed by transmission electron microscope (TEM), indicates the core-shell structure of glass-ceramics nanoparticles in between 10–50 nm range. The incorporation of Er3+ and Yb3+ into the crystalline matrix was confirmed and analyzed from X-ray diffraction (XRD) analysis. The increased crystal size according to increased temperatures shows the CaF 2 crystal growth. The up-conversion luminescence properties of the prepared nano-glass ceramics were tested by using a 980 nm laser. The photoluminescence emission showed two peaks at green (548 nm and 528 nm) emission and one at red emission (626 nm). Additionally, the cell viability study of the Er3+-Yb3+ doped CaF 2 nano glass-ceramics was performed using MG-63 osteoblast cells and it shows significant cell growth as compared to control over a period of 24 h. The result confirmed that the prepared nano-glass-ceramics can be a potential optical material for bio-imaging. [ABSTRACT FROM AUTHOR]