Structural, thermal, and optical properties of Pr3+/Yb3+ co-doped oxyhalide tellurite glasses and its nano-crystalline parts

Nano-crystalized glass-ceramics and ceramics co-doped with Pr3+/Yb3+ have been successfully prepared by heat treatment of the precursor oxyhalide glass sample synthesized by melt-quench method. Thermal measurement of glass sample shows its glass transition temperature (Tg), and onset crystallization temperature (Tc). Formation of nano-crystals was verified by X-ray diffraction patterns and transmission electron microscopy (TEM) images. Values of optical band gap (Eopt) were found to be 2.85 eV and 1.54 eV for direct and indirect transitions, respectively. Up and downconversion emission spectra recorded with 976 and 532 nm laser wavelengths show emission from Pr3+ ions. Emission of Pr3+ enhances approximately thirty times when Yb3+ ion is added with the matrix. The Stark splitting and the intensity of different emission bands increase effectively when we approach to ceramic via glass-ceramic sample. Intense upconversion emission observed by naked eyes has been quantified in terms of standard chromaticity diagram (CIE). Power dependence study shows that the upconversion of NIR radiation to visible takes place mainly via photon avalanche (PA) process. Upconversion mechanisms have been discussed in terms of excited state absorption (ESA) and energy transfer (ET) processes.

Figure optionsDownload as PowerPoint slideHighlights
► Effect of ceramization on the structural and optical properties has explored.
► Above mentioned properties improve towards ceramization to a good extent.
► Higher energy transitions get better under 976 and 532 nm laser excitations.
► Photon avalanche has been observed in critical power region of 976 nm diode laser.
► CIE diagram shows the overall emission of glasses and its nano-crystalline parts.