Glass - Back to the Future!

Presenting Author:
Quyen Le

article posted 7 April 2016

Quyen Le in 2006 got her BSc, Chemical Engineering, CanTho University, Viet Nam. In 2009 a Master of Engineering Advanced Manufacturing Technology, University of South Australia, Australia. Then in 2015 started a PhD at Otto Schott Institute of Materials Research, Friedrich Schiller University of Jena, Germany.

Structural and spectroscopic analyses of copper doped fluoride phosphate sulfate glasses

Q.H. Lea, D. Mönckea, E. I. Kamitsosb & L. Wondraczeka
a Otto-Schott-Institut of Materials Research, Friedrich- Schiller-Universität, Fraunhoferstraße 6, 07743 Jena, Germany
b Theoretical and Physical Chemistry Institute, National Hellenic Research Foundation, Vass. Constantinou Ave. 48, 11635 Athens, Greece

Cu2+ doped fluoride-phosphate-sulfate (FPS) glasses with composition (100-x)(MgF2, CaF2, SrF2,AlF)–(x-y)Sr(PO3)2-ySrSO4 in mol% (x=10, 15, 20; y=0-20; x>y) were studied by a range of spectroscopic techniques such as UV-Vis absorption, electron spin resonance (ESR), infrared (IR), Raman and magic angle spinning nuclear magnetic resonance (MAS-NMR) spectroscopy.
FPS glasses containing 500 ppm of copper oxide (CuO) were prepared by both melt casting and melt quenching. The presence of d9 ions Cu2+ results in a broad optical absorption band at 800 to 850 nm, typical for Cu2+ ions in Jahn-Teller distorted octahedral sites. The intensity of glass colour depends on the ratio of blue Cu2+ (d9) to colourless Cu1+ (d10) ions.
The absorption band depends on the ligand field splitting energies of the ligands which bond to the Cu2+ ions. In FPS glasses, fluoride, phosphate and sulfate ligands are available for bonding. For an average bonding environment it would be expected that the Cu2+ absorption band shifts with increasing optical basicity of the glass to higher wavelength, however, it seems that Cu2+ ions bond preferentially to phosphate ligands.
ESR measurements were used to study the site geometry and bonding character of the Cu2+ ions. The low Cu-levels were chosen to avoid clustering and ion–ion interactions between Cu ions.
The substitution of Sr(PO3)2 by SrSO4 is probed by IR, Raman and NMR spectroscopic measurements. As has been shown by Ebeling et al[1], the fundamental glass forming entities for such FPS glasses are SO42-, PO34- and P2O74- ions, as well as AlF6 and Al(O,F)6 octahedra which are cross linked through Al–O–P bonds, and by ionic bonds of the alkaline earth cations.

[1] P. Ebeling, D. Ehrt, M. Friedrich, Radiation-induced color centers in anion doped phosphate glasses, Phosphorus Research Bulletin 10 (1999) 484-489.