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The study of devitrification processes in heavy-metal fluoride glasses
Ian R Dunkley1, Reginald W Smith, Sudhanshu Varma
1Department of Mechanical and Materials Engineering, Queen's University, Kingston, Ontario, Canada K7L 3N6.
Annals of the New York Academy of Sciences
|January 13, 2005
Summary
Heavy-metal fluoride glasses offer ultralow loss optical fibers but suffer from devitrification. This study investigates viscosity and devitrification in ZBLAN glass to enable high-quality fiber production.
Area of Science:
- Materials Science
- Optical Fiber Technology
- Glass Science
Background:
- Heavy-metal fluoride glasses, particularly ZBLAN (53ZrF(4)-20BaF(2)-4LaF(3)-3AlF(3)-20NaF), show potential for ultralow loss optical fibers due to their extended transparency range into the mid-IR.
- Devitrification instability during synthesis and fiber drawing limits the commercial application of these promising materials.
- Current understanding of nucleation and crystallization mechanisms in fluoride glasses is insufficient for developing effective stabilization technologies.
Purpose of the Study:
- To investigate the critical role of viscosity in the devitrification mechanism of ZBLAN glass.
- To determine missing viscosity data within the fiber-drawing and crystallization temperature regions for ZBLAN glass.
- To explore the proposed mechanisms of shear thinning and hydrostatic pressure in causing devitrification during fiber drawing.
Main Methods:
- Development and utilization of a piezoelectric viscometer to measure viscosity data in critical temperature ranges.
- Analysis of ZBLAN glass properties in both terrestrial (1 g) and reduced gravity environments.
- Exploration of the realism of shear thinning and hydrostatic pressure as causes for devitrification.
Main Results:
- Viscosity data in the fiber-drawing and crystallization regions for ZBLAN glass are being obtained using a novel piezoelectric viscometer.
- Previous studies suggest microgravity and containerless processing can suppress devitrification in ZBLAN glass.
- The study aims to validate or refute the proposed roles of shear thinning and hydrostatic pressure in ZBLAN glass devitrification.
Conclusions:
- Accurate viscosity data is crucial for understanding and controlling ZBLAN glass devitrification during fiber drawing.
- Further research into devitrification mechanics, including the influence of external factors like gravity and pressure, is needed.
- Developing methods to suppress devitrification will enable the production of high-quality fluoride optical fibers for advanced applications.