Journal of Physical Studies 19(4), Article 4703 [6 pages] (2015)
DOI: https://doi.org/10.30970/jps.19.4703
THE EFFECT OF Ga ON THE STRUCTURAL AND OPTICAL PROPERTIES OF THE As30Se50Te20 CHALCOGENIDE GLASS
Ya. Shpotyuk{1,2}, B. Pavlyk{1}, S. Rykhlyuk{3}, C. Boussard-Pledel{2}, V. Nazabal{2}, B. Bureau{2}
{1}Department of Electronics, Ivan Franko National University of Lviv,
107, Tarnavskoho St., Lviv, UA-79017, Ukraine}
{2}Glasses and Ceramics Laboratory, University of Rennes 1,
2, ave. du Thabor, Rennes, 35065, France
{3}Department of Optoelectronics and Information Technologies,
Ivan Franko National University of Lviv,
107, Tarnavskoho St., Lviv, UA--79017, Ukraine
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Chalcogenide glasses (ChG) are known to be one of most promising candidates for device application in IR photonics and optics. Upon quenching from a melt, they usually form bulk glassy rods which can be shaped into fibers. Because of excellent transparency from visible to far IR range, the ChG have a great potential for different sensing applications in atmospheric and space telecommunication, ${\rm C}_{}{\rm O}_{2}$ detection, bio-sensing, etc.
Being doped with rare-earth (RE) ions, the ChG significantly extend their functionalities due to numerous radiative transitions appearing in the IR region. However, most RE ions are slightly solved in ChG, which causes a real problem with emission activation in pure chalcogenide matrices. This problem can be solved by introducing some doping additives such as Ga or In in ChG. But, on the other hand, Ga contained glasses demonstrate an obvious tendency to nanostructurization by forming intrinsic inhomogeneities because of strong Ga affinity to chemical interaction with chalcogens. This process can result in phase separation, nucleation and, finally, crystal growth leading to stabilization of different ${\rm Ga}_{2}{\rm Se}_{3}$ crystalline polymorphs.
In this work, several experimental techniques were employed to study the effect of Ga additions in ${\rm As}_{30}{\rm Se}_{50}{\rm Te}_{20}$ glass including optical spectroscopy in visible and IR region, X-ray diffraction, differential scanning calorimetry, as well as scanning electron microscopy with energy-dispersive spectroscopy.
It was shown that 1 at. 0a can be incorporated into ${\rm As}_{30-x}{\rm Ga}_{x}{\rm Se}_{50}{\rm Te}_{20}$ glass without crystallization. This glass was successfully drawn into a fiber with minimal optical loses around 3 dB/m in the 5-9 mm range which allows to use this composition for further RE doping. The alloys with a higher Ga content were partly crystallized with the appearance of ${\rm Ga}_{2}{\rm Se}_{3}$ cubic polymorphs which was confirmed by X-ray diffraction measurements and energy dispersive X-ray analysis. Moreover, the results of scanning electron microscopy showed that in the case of ${\rm As}_{28}{\rm Ga}_{2}{\rm Se}_{50}{\rm Te}_{20}$, the observed crystalline inclusions were nearly 200-300 nm in size, while in ${\rm As}_{25}{\rm Ga}_{5}{\rm Se}_{50}\rm{Te}_{20}$ these inclusions become larger up to 40-70 micrometers in size. These crystallites provoke Rayleigh (on nano-sized crystallites) and Mie (on micro-sized crystallites) scattering causing loses in optical transmission.
PACS number(s): 77.84.Bw, 78.40.Fy, 42.81.Qb
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