Crystallization study of heavy metal fluoride glasses ZBLAN by Raman spectroscopy

Abstract

Heavy metal fluoride glass ZBLAN, with molar composition ZrF4(53)–BaF2(20)–LaF3(4)–AlF3(3)–NaF(20), was studied in vacuum at high temperatures up to 480°C by Raman spectroscopy. The vitreous glass was found to crystallize at 330°C, most probably to β‐BaZrF6 crystallites. High‐temperature experiments in air were also carried out and ZrO2 was formed at the surface of the sample. Doping by SiO2 increases the crystallization temperature by 25°C for experiments performed in air, while PbO2 dopants are found to react with the host. © 1997 John Wiley & Sons, Ltd.

Raman Microspectroscopy of Normal Erythrocytes and Plasmodium Berghei -Infected Erythrocytes

“…The blood cells can be easily identi ed on the screen and for the parasiteinfected erythrocytes, the presence of the parasite can be observed in the erythrocytes. This observation was consistent with our study of the Raman spectra obtained using the 488-nm Ar 1 laser 16 illumination and also in this study. This system allows one to easily select the spot on the sample for investigation.…”

“…The Raman experiments were carried out with a modi ed micro-Raman system, in which an Olym pus microscope with a CCTV system is coupled to a Spex 1704 spectrometer equipped with a liquid nitrogen cooled charge-coupled device (CCD) detector. 16 In this modi ed system, as shown in Fig. 1, the coupling optics are arranged in a box that is linked to the modi ed optical microscope by a mechanical arm and…”

Low thermal expansion ZBLAN‐based glass ceramics containing CaZrF6 crystals

“…Both ZBLAN and CZBLAN samples exhibited four identical Raman peaks located at 190, 425, 480, and 573 cm −1 . Based on the structure and vibration characteristics of ZBLAN glass, we confirmed that the Raman peak of CZBLAN GCs at approximately 573 cm −1 is due to the symmetrical tensile vibrations of the Zr–F bonds in the ZrF 6 octahedron 21,22 . The peak located at 480 cm −1 corresponds to the antisymmetric vibrations of Zr–F nb , and the band near 425 cm −1 is due to the antisymmetric vibrations of Zr–F b 22,23 .…”

Rare-Earth Doped Optical Fibers

“…For example, the superposition of all the possible vibrational energies (phonons) for silica form a continuum that covers a band of 40 THz ( phonon  7.5 m, E1300 cm -1 ) with the strongest mode overlapping at 7.5-15.5 THz that corresponds to 19.35 and 40 m (250E520 cm -1 ), respectively (Agrawal, 1989). By contrast, a fluoride-based glass, ZBLAN for example, presents a much narrower band with mode overlapping at the edge 15 THz that corresponds to  phonon 20 m (E580 cm -1 ) (Luu-Gen & Chen- Ke, 1996;Quin et al 1997). Then, all the energy levels separated less than this GAP, 1300 cm -1 for silica and 580 cm -1 for ZBLAN, are thermally connected and the higher instantaneously feeds population into the lower.…”