Creating Durable Chalcogenide With Controlled Crystallization

Rebecca Welch1*, Rashi Sharma2, The OML Crew2, Kathleen Richardson2, Mario Affatigato1 1Department of Physics, Coe College, Cedar Rapids, IA 2CREOL, Center for and Photonics, University of Central Florida, Orlando, FL Chalcogenide glasses

• Transmission in (IR) wavelength • Wide range of applications including • Optical fibers • • Sensors

2 Chalcogenide glasses However… • Very brittle • Poor chemical durability Creating would solve this which leads to the creation of a ceramic. Must be careful though! Crystals cause the loss of transmission. 3 Glass Ceramics A glass ceramic is created when the glass undergoes timed heat treatments to allow the development of crystals. Glass ceramics are stronger than glass due to: • Uniform particle distribution • Little porosity More More Heat ♦ ♦ ♦ Heat ♦ Heat ♦ ♦ ♦ ♦ Longer Base glass Nucleation step Growth step Time Continued Growth step

4 Glass Ceramics Also have a higher fracture toughness because fracture fronts are forced to go around the .

Traditional glass surface when Glass ceramic version when exposed to a fracture-causing force. exposed to same force. 5 Glass Ceramics Even more importantly… Crystal growth allows for tailorable refractive index by controlling the volume fraction of the crystals and the glass!

neff ≈ (Vglass)(nglass) + (Vcrystal)(ncrystal) But more crystals also leads to less transmission due to: • Scattering – due to crystals • Absorption – natural loss from glass & from crystals • Fresnel loss – surface reflection

6 The GAP-Se Chalcogenide Glass

20GeSe2-60As2Se3-20PbSe has been used in heat treatments previously. ----ucleation ---- Growth I A I I I Nucleation step:

Q.) y 220 ℃ for 2 hours -+-> ~"' I cu > I Growth step (30 mins): ·--+-> I -"'cu I ~ I I • 250 ℃ I I I • 260 ℃ • 270 ℃ ------/1 180 190 200 210 220 230 240 250 260 270 280 290 7 Temp ratur [°C] The GAP-Se Chalcogenide Glass Heat treatments led to little increase in hardness with high scattering. 60 180

175 50 170 ll 165 .-, 40 I r-, r N L...... J~ 0 I I ~ 160 <.) ---,._ c= f oI) ro ---- Base -~ 30 I ~en 155 I en ens 0 I c= roc= I --- 220°C-2hrs 150 I,.,. I "8ro E-< I ::r: 20 I ,-: I - • - • 220°C-2hrs, 250°C-30min 145 I I i I I - •• - 220°C-2hrs, 260°C-30min 140 I I •·· • • •·· • • •·· • 220°C-2hrs , 270°C-30min 135 I .•·/ 130 0 8 Base 220°C-2hrs (N) N+250°C-30min N+260°C-30min N+270 °C-30min 0 2 4 6 8 10 12 Wavelength f µm The GAP-Se Chalcogenide Glass Heat treatments caused more scattering due to the glass’s phase separation.

9 Transmission Electron Microscopy (TEM) images of GAP-Se glass. The New GAP-Se Chalcogenide Glass

New glass versions created by Amorphous Materials Inc. (AMI) are completely homogenous!

Transmission Electron Microscopy (TEM) images of AMI samples collected by Dr. Kang

10 Purpose & Methods

See if these new glasses can undergo crystallization, leading to a more durable material with low optical losses. 1. Use heat treatments to create crystals. 2. Observe crystal growth with SEM & XRD 3. Measure Vicker’s hardness of the glass. 4. Measure density. 5. Measure transmission with FTIR.

11 Heat Treatments

Nucleation Step: Glasses kept at 220 ℃ for 2 hours followed by growth steps. Four samples: 1. Base – no heat treatment 2. 30 minute treatment at 250 ℃ 3. 30 minute treatment at 260 ℃ 4. 30 minute treatment at 270 ℃ • 60 mins at 270 ℃ • 90 mins at 270 ℃ 12 Observance of Crystal Growth

Scanning Electron Microscopy Results

Glass with 60 minutes at 270 ℃ 13 Mechanical Results

Vicker’s Hardness Measurements

190 185 180 175 2 New glass 170 165 Phase separated 160 □ glass

Kgf/mm 155 150 145 140 Base 250 260 270 270-30 Heat Treatment (℃) 14 Mechanical Results Density Measurements

5.02 5 4.98

) 4.96 New glass 3 4.94 Phase separated 4.92 □ 4.9 glass 4.88 4.86 4.84 Density (g/cm 4.82 4.8 Base 250 260 270 270-30min Heat Treatment (℃) 15 Transmission Results FTIR Measurements of old phase separated glass with new ones N1 - Ba se HT-250 70 Base HT-260 HT- 270 60 250 ℃ 60 260 ℃

50 270 ℃ I 50 I ,--, 40 I ~ r L.....J 40 I I f I Base I 30 I I --- 220°C-2hrs I I % Transmission I - • - • 220°C-2hrs , 250°C-30min 20 I I i I I - .. - 220 °C-2hrs , 260°C-30min 10 10 I I , I •··· • • •·· • • •·· 220°C-2hrs , 270°C-30min ..· 0 0 5 10 15 20 25 0 2 4 6 8 10 12 16 Wavelength [µm] Wavelength/Wavelength/ 6 µmm 17 Transmission Results FTIR Measur

ements oflongerheattr Transmission/ % 10 20 30 40 50 60 70 1.0E+00 0 6 1

6.0E+00

1.1E+01 Wavelength / µm 11 1.6E+01

16 eatment time 2.1E+01 21 mm) (2.50 Base mm) 270 (2.80 (2.66 mm) 270-30 min min. 270 270 Base

℃ ℃

60 - Conclusions & Future Works

• We were able to use heat treatments to increase the hardness of our glass with low optical loss. • Longer heat treatments need to be completed to get the maximum hardness values. • We can use these methods to create more durable chalcogenide glasses.

18 Works Cited

1. Anupama Yadav, A. B., Myungkoo Kang, Laura Sisken, Charmayne Smith, Jason Lonergan, Cesar Blanco, Michael Antia, Megan Driggers, Andrew Kirk, Clara Rivero-Baleine, Theresa Mayer, Andrew Swisher, Alexej Pogrebnyakov, A. R. Jr. Hilton, Greg Whaley, Thomas J. Loretz, Anthony Yee, Greg Schmidt, Duncan T. Moore, Kathleen A. Richardson, Melt property variation in GeSe2-As2Se3-PbSe glass cermaics for infrared gradient refractive index (GRIN) applications. Int. J. Appl. Glass Sci. 2018, 10, 27-40. 2. Anupama Yadav, M. K., Charmayne Smith, Jason Lonergan, Andrew Buff, Laura Sisken, Karima Chamma, Cesar Blanco, Joe Caraccio, Theresa Mayer, Clara Rivero-Baleine, Kathleen Richardson, Influence of phase separation on structure-property relationships in the (GeSe2-3As2Se3)1-xPbSex glass system. Phys. Chem. Glasses: Eur. J. Glass Sci. Technol. B 2017, 58 (4), 115- 126. 3. Benn Gleason, K. R., Laura Sisken, Charmayne Smith, Refractive index and thermo-optic coefficients of Ge-As-Se chalcogenide glasses. Int. J. Appl. Glass Sci. 2016, 7 (3), 374-383. 4. Laura Sisken, C. S., Andrew Buff, Myungkoo Kang, Karima Chamma, Peter Wachtel, J. David Musgraves, Clara Rivero-Baleine, Andrew Kirk, Matthew Kalinowski, Megan Melvin, Theresa S. Mayer, Kathleen Richardson, Evidence of spatially selective refractive index modification in 15GeSe2-45As2Se3-40PbSe glass ceramic through correlation of structure and optical property measurements for GRIN applications. Optical Matierals Express 2017, 7 (9), 3077-3092. 5. Xia, F. Z., Xianghua; Chen, Guorong; Ma, Hongli; Adam, J. L., Glass formation and crystallization behavior of a novel GeS2- Sb2S3-PbS chalcogenide glass system. J. Am. Ceram. Soc. 2006, 89 (7), 2154-7. 6. Hua Wang, X. Z., GuangYang, Yinsheng Xu, Hongli Ma, J. L. Adam, Zhen’an Gu, Guorong Chen, Micro-crystallization of the infrared transmitting chalcogenide glass in GeSe2-As2-Se3-PbSe system. Ceramics International 2009, 35, 83-86. 19 , ----- '