Chalcogenide Glasses for Infrared Applications: New Synthesis Routes and Rare Earth Doping

Persistent Link:
http://hdl.handle.net/10150/223357
Title:
Chalcogenide Glasses for Infrared Applications: New Synthesis Routes and Rare Earth Doping
Author:
Hubert, Mathieu
Issue Date:
2012
Publisher:
The University of Arizona.
Rights:
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
Embargo:
Release after 12-Oct-2012
Abstract:
Chalcogenide glasses and glass-ceramics present a high interest for the production of thermal imaging lenses transparent in the 3-5 μm and 8-12 μm windows. However, chalcogenide glasses are conventionally synthesized in sealed silica ampoules which have two major drawbacks. First, the low thermal conductivity of silica limits the sample dimensions and second the silica tubes employed are single use and expensive, and represent up to 30% of the final cost of the material. The present work therefore addresses the development of innovative synthesis methods for chalcogenide glass and glass-ceramics that can present an alternative to the silica tube route. The method investigated involves melting the raw starting elements in reusable silica containers. This method is suitable for the synthesis of stable chalcogenide glasses compositions such as GeSe₄ but uncontrolled crystallization and homogenization problems are experienced for less stable compositions. The second approach involves preparation of amorphous chalcogenide powders by ball milling of raw elements. This mechanosynthesis step is followed by consolidation of the resulting powders to produce bulk glasses. Hot Uniaxial Pressing is suitable for compositions stable against crystallization. However, uncontrolled crystallization occurs for the unstable 80GeSe₂-20Ga₂Se₃ glass composition. In contrast consolidation through Spark Plasma Sintering (SPS) allows production of bulk glasses in a short duration at relatively low temperatures and is appropriate for the synthesis of unstable glasses. A sintering stage of only 2 min at 390°C is shown to be sufficient to obtain infrared transparent 80GeSe₂-20Ga₂Se₃ bulk glasses. This method enables the production of lenses with a 4-fold increase in diameter in comparison to those obtained by melt/quenching technique. Moreover, increasing the SPS treatment duration yielded infrared transparent glass-ceramics with enhanced mechanical properties. This innovative synthesis method combining mechanosynthesis and SPS has been patented in the framework if this study. The controlled etching of 80GeSe₂-20Ga₂Se₃ glass-ceramics in acid solution yields nanoporous materials with enhanced surface area. The porous layer created on the surface of the glass-ceramic is shown to play the role of anti-reflection coating and increase the optical transmission in the infrared range by up to 10%. These materials may have potential for the production of sensors with increased sensitivity in the infrared. The influence of indium and lead addition on the thermal and optical properties of the 80GeSe₂-20Ga₂Se₃ glass has also been assessed. Increased In or Pb contents tend to decrease the Tg of the glasses and shift the optical band gap toward higher wavelengths. A systematic ceramization study emphasizes the difficulty of controlling the crystallization for glasses in the systems GeSe₂-Ga₂Se₃-In₂Se₃ and GeSe₂-Ga₂Se₃-PbSe. No crystallization of the In₂Se₃ and PbSe crystalline phase was obtained. Finally, the possibility of producing rare-earth doped 80GeSe₂-20Ga₂Se₃ glass-ceramics transparent in the infrared region up to 16 μm is demonstrated. Enhanced photoluminescence intensity and reduced radiative lifetimes are observed with increased crystallinity in these materials.
Type:
text; Electronic Dissertation
Keywords:
Glasses; Mechanosynthesis; Rare Earth Doping; Spark Plasma Sintering; Materials Science & Engineering; Chemical Etching; Glass-ceramics
Degree Name:
Ph.D.
Degree Level:
doctoral
Degree Program:
Graduate College; Materials Science & Engineering
Degree Grantor:
University of Arizona
Advisor:
Lucas, Pierre

Full metadata record

DC FieldValue Language
dc.language.isoenen_US
dc.titleChalcogenide Glasses for Infrared Applications: New Synthesis Routes and Rare Earth Dopingen_US
dc.creatorHubert, Mathieuen_US
dc.contributor.authorHubert, Mathieuen_US
dc.date.issued2012-
dc.publisherThe University of Arizona.en_US
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en_US
dc.description.releaseRelease after 12-Oct-2012en_US
dc.description.abstractChalcogenide glasses and glass-ceramics present a high interest for the production of thermal imaging lenses transparent in the 3-5 μm and 8-12 μm windows. However, chalcogenide glasses are conventionally synthesized in sealed silica ampoules which have two major drawbacks. First, the low thermal conductivity of silica limits the sample dimensions and second the silica tubes employed are single use and expensive, and represent up to 30% of the final cost of the material. The present work therefore addresses the development of innovative synthesis methods for chalcogenide glass and glass-ceramics that can present an alternative to the silica tube route. The method investigated involves melting the raw starting elements in reusable silica containers. This method is suitable for the synthesis of stable chalcogenide glasses compositions such as GeSe₄ but uncontrolled crystallization and homogenization problems are experienced for less stable compositions. The second approach involves preparation of amorphous chalcogenide powders by ball milling of raw elements. This mechanosynthesis step is followed by consolidation of the resulting powders to produce bulk glasses. Hot Uniaxial Pressing is suitable for compositions stable against crystallization. However, uncontrolled crystallization occurs for the unstable 80GeSe₂-20Ga₂Se₃ glass composition. In contrast consolidation through Spark Plasma Sintering (SPS) allows production of bulk glasses in a short duration at relatively low temperatures and is appropriate for the synthesis of unstable glasses. A sintering stage of only 2 min at 390°C is shown to be sufficient to obtain infrared transparent 80GeSe₂-20Ga₂Se₃ bulk glasses. This method enables the production of lenses with a 4-fold increase in diameter in comparison to those obtained by melt/quenching technique. Moreover, increasing the SPS treatment duration yielded infrared transparent glass-ceramics with enhanced mechanical properties. This innovative synthesis method combining mechanosynthesis and SPS has been patented in the framework if this study. The controlled etching of 80GeSe₂-20Ga₂Se₃ glass-ceramics in acid solution yields nanoporous materials with enhanced surface area. The porous layer created on the surface of the glass-ceramic is shown to play the role of anti-reflection coating and increase the optical transmission in the infrared range by up to 10%. These materials may have potential for the production of sensors with increased sensitivity in the infrared. The influence of indium and lead addition on the thermal and optical properties of the 80GeSe₂-20Ga₂Se₃ glass has also been assessed. Increased In or Pb contents tend to decrease the Tg of the glasses and shift the optical band gap toward higher wavelengths. A systematic ceramization study emphasizes the difficulty of controlling the crystallization for glasses in the systems GeSe₂-Ga₂Se₃-In₂Se₃ and GeSe₂-Ga₂Se₃-PbSe. No crystallization of the In₂Se₃ and PbSe crystalline phase was obtained. Finally, the possibility of producing rare-earth doped 80GeSe₂-20Ga₂Se₃ glass-ceramics transparent in the infrared region up to 16 μm is demonstrated. Enhanced photoluminescence intensity and reduced radiative lifetimes are observed with increased crystallinity in these materials.en_US
dc.typetexten_US
dc.typeElectronic Dissertationen_US
dc.subjectGlassesen_US
dc.subjectMechanosynthesisen_US
dc.subjectRare Earth Dopingen_US
dc.subjectSpark Plasma Sinteringen_US
dc.subjectMaterials Science & Engineeringen_US
dc.subjectChemical Etchingen_US
dc.subjectGlass-ceramicsen_US
thesis.degree.namePh.D.en_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.disciplineMaterials Science & Engineeringen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.advisorLucas, Pierreen_US
dc.contributor.committeememberPotter, B. G.en_US
dc.contributor.committeememberUhlmann, Donalden_US
dc.contributor.committeememberCalvez, Laurenten_US
dc.contributor.committeememberBureau, Brunoen_US
dc.contributor.committeememberLucas, Pierreen_US
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