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Glass-forming regions of ternary GeTeAl and GeTeSb chalcogenide glasses
]OURNA L OF
,,.,, lnl -CRYSTALLINE SOLIDS
Journal of N o n-C rystalline So lids139 (1992 ) 177-178 North-Holland
Letter to the Editor
Glass-forming regions of ternary Ge-Te-A1 and Ge-Te-Sb chalcogenide glasses To s h io Katsuyama and Hiroyoshi M a t s u m u r a Central Research Laboratory, Hitachi Ltd. Kokubunji, Tokyo 185, Japan Received 15 July 1991 Revised manuscript received 11 October 1991
Glass-forming regions of ternary G e - T e - A l and G e - T e - S b chalcogenide glasses are examined. The Ge-Te-A1 glass shows a relatively broad glass-forming region under liquid N 2 quenching. Glass transition and crystallization temperatures of G e - T e - A I glasses are about 170 and 270°C, respectively, higher than those of binary G e - T e glass. It is shown that the glass-forming region of G e - T e - S b glass is much smaller than that of G e - T e - A l glass, indicating that the Ge-Te-A1 glass has a relatively stable vitreous state and therefore has capabilities applicable to infrared optical fiber material.
Infrared optical fibers operating at 2-12 I~m in wavelength are required for infrared sensing applications such as radiometric thermometer, and CO 2 laser power applications such as laser surgery [1]. The Te-based chalcogenide glasses are candidates for such applications because their infrared absorption edges are located in a wavelength region above 12 Ixm [2]. However, only a few compositions such as G e - T e - and As-Tebased glasses have been investigated as memory switching glasses [3-7]. In this letter, ternary G e Te-A1 and G e - T e - S b compositions are studied for use as infrared optical fiber material. Glassforming regions and some results of glass transition and crystallization temperatures are reported. Starting materials for the experiment were 4-N Ge, 4-N Te, 3-N AI and 3-N Sb powders. These materials were weighed into a quartz ampoule (outer dia. 11 mm, inner dia. 5 mm), which was then evacuated and sealed under a vacuum of about 10 -5 Torr. The ampoules were heated at 1000°C for 12 h in a rocking furnace. Then, after slowly cooling to 700-800°C, they were quenched into liquid N 2.
Glass-forming regions were determined by Xray powder diffraction. Glass transition and crystallization temperatures were measured using a standard differential scanning calorimeter (heating rate 10°C/min). The reproducibility of the experimental data was better than _+5°C. The experimental result of the glass-forming region of the ternary G e - T e - A 1 composition is shown in fig. 1. Glass transition, Tg, and crystallization, Tx, temperatures of Ge5TesoA115 and Te70A130 glasses are shown in table 1 with data
Te
10~-4kk9 0
e? O\To 50 10 Ges°le5°
20 30 40 500 At ~" Als°Teh°
Fig. 1. Glass-forming region of ternary Ge-Te-A] glass under liquid N 2 quenching, o, glassy; o, crystalline; meshed region:
0022-3093/92/$05.00 © 1992 - Elsevier Science Publishers B.V. All rights reserved
glass-forming region.
178
T. Katsuyama, H. Matsumura / Glass-forming regions of ternary chalcogenide glasses
Table 1 Glass transition temperatures, Tg, and crystallization temperatures, Tx, of G e - T e - A I and G e - T e - S b glasses Composition (mol%)
Tg (°C)
Tx (°C)
GesTeso A115 Te7oA13o Ge2oTeso Ge is.75Tesl.25 Ge i6.25Te83.75 Ge16.sTe82Sbl. 5
172 _+5 170 151 150 141 145
277 + 5 265 227 221 229 229
for binary G e - T e glasses given for comparison. The Tg and Tx values for binary G e - T e glasses in the table are almost the same as those already reported by Savage [5]. This consistency supports the validity of our experimental data for G e - T e A1 glasses. On the other hand, the glass-forming region of ternary G e - T e - S b composition is shown in fig. 2. The experimental data of Tg and Tx for Ge16.sTe82Sba. s glass are also shown in table 1. Figure 1 shows that, for the ternary G e - T e - A I composition, the glassy state can be obtained in a relatively broad region; meaning it is relatively stable. Further, table 1 shows that the Tg values of the G e - T e - A 1 glasses containing 15-30 mol% of A1 are constant (about 170°C). The Tx values are also constant (about 270°C). Therefore, these temperatures show no dependence on the A1 content. For binary G e - T e glasses, the Tg values are 140-150°C and the Tx values are 220-230°C. Therefore, it can be seen that A1 in the G e - T e glasses increases Tg by at least 20°C and Tx by at least 40°C. These temperature increases indicate that ternary G e - T e - A 1 glasses are more stable than binary G e - T e glasses. On the other hand, fig. 2 shows that the glassforming region for G e - T e - S b composition is clearly smaller than that of the G e - T e - A 1 glass system. Further, the G e - T e - S b glass shows no increase of Tg and Tx compared with binary G e Te glasses. Therefore, it is clear that G e - T e - A 1 glasses are more stable than G e - T e - S b glasses. The glass stability of ternary G e - T e - A 1 glasses indicates the possibility of these glasses being used in infrared optical fiber material applications. In particular, it is worth mentioning that a high-speed drawing method has been recently developed, resulting in a successful drawing of a
Te
40?VVV 60 10 20 30 40
0 S bz~T%0
Ge
>
Ge4oTe60
Fig. 2. Glass-forming region of ternary O e - T e - S b glass under liquid N 2 quenching. ©, glassy; o, crystalline; meshed region: glass-forming region.
glass composition with a low Tg value of around 170°C [2]. Therefore, an increase in Tg up to 170°C in the G e - T e - A I glass system suggests the possibility of drawing the glass into a low-loss optical fiber. However, the multiphonon edge will be shifted toward a shorter wavelength region because of the small mass of A1 in the G e - T e - A 1 glass. Therefore, it is preferable to use a glass region with a relatively low A1 content, but with still high Tg and Tx, in realizing an optical fiber with a low loss at around 10 Ixm. In summary, the G e - T e - A 1 glasses show a relatively broad glass-forming region under liquid N 2 quenching. For G e - T e - A 1 glass, glass transition and crystallization temperatures are higher than those of binary G e - T e glass by at least 20°C and 40°C, respectively. On the other hand, the glass-forming region of G e - T e - S b glass is smaller than that of the G e - T e - A 1 glass. The G e - T e - A 1 glass appears to have capabilities applicable for use as infrared optical fiber material because of its stable vitreous state.
References [1] T. Katsuyama and H. Matsumura, Infrared Optical Fibers (Adam Hilger, London, 1989) pp. 212-219. [2] T. Katsuyama and H. Matsumura, Appl. Phys. Lett. 49 (1986) 22. [3] T. Takamori, R. Roy and G.J. McCarthy, Mater. Res. Bull. 5 (1970) 529. [4] S. Iizima, M. Sugi, M. Kikuchi and K. Tanaka, Solid State Commun. 8 (1970) 153. [5] J.A. Savage, J. Mater. Sci. 6 (1971) 964. [6] J.A. Savage, J. Non-Cryst. Solids 11 (1972) 121. [7] S. Bordas, J. Casas-Vazquez, N. Clavaguera and M.T. Clavaguera-Mora, Thermochim. Acta 28 (1979) 387.
,,.,, lnl -CRYSTALLINE SOLIDS
Journal of N o n-C rystalline So lids139 (1992 ) 177-178 North-Holland
Letter to the Editor
Glass-forming regions of ternary Ge-Te-A1 and Ge-Te-Sb chalcogenide glasses To s h io Katsuyama and Hiroyoshi M a t s u m u r a Central Research Laboratory, Hitachi Ltd. Kokubunji, Tokyo 185, Japan Received 15 July 1991 Revised manuscript received 11 October 1991
Glass-forming regions of ternary G e - T e - A l and G e - T e - S b chalcogenide glasses are examined. The Ge-Te-A1 glass shows a relatively broad glass-forming region under liquid N 2 quenching. Glass transition and crystallization temperatures of G e - T e - A I glasses are about 170 and 270°C, respectively, higher than those of binary G e - T e glass. It is shown that the glass-forming region of G e - T e - S b glass is much smaller than that of G e - T e - A l glass, indicating that the Ge-Te-A1 glass has a relatively stable vitreous state and therefore has capabilities applicable to infrared optical fiber material.
Infrared optical fibers operating at 2-12 I~m in wavelength are required for infrared sensing applications such as radiometric thermometer, and CO 2 laser power applications such as laser surgery [1]. The Te-based chalcogenide glasses are candidates for such applications because their infrared absorption edges are located in a wavelength region above 12 Ixm [2]. However, only a few compositions such as G e - T e - and As-Tebased glasses have been investigated as memory switching glasses [3-7]. In this letter, ternary G e Te-A1 and G e - T e - S b compositions are studied for use as infrared optical fiber material. Glassforming regions and some results of glass transition and crystallization temperatures are reported. Starting materials for the experiment were 4-N Ge, 4-N Te, 3-N AI and 3-N Sb powders. These materials were weighed into a quartz ampoule (outer dia. 11 mm, inner dia. 5 mm), which was then evacuated and sealed under a vacuum of about 10 -5 Torr. The ampoules were heated at 1000°C for 12 h in a rocking furnace. Then, after slowly cooling to 700-800°C, they were quenched into liquid N 2.
Glass-forming regions were determined by Xray powder diffraction. Glass transition and crystallization temperatures were measured using a standard differential scanning calorimeter (heating rate 10°C/min). The reproducibility of the experimental data was better than _+5°C. The experimental result of the glass-forming region of the ternary G e - T e - A 1 composition is shown in fig. 1. Glass transition, Tg, and crystallization, Tx, temperatures of Ge5TesoA115 and Te70A130 glasses are shown in table 1 with data
Te
10~-4kk9 0
e? O\To 50 10 Ges°le5°
20 30 40 500 At ~" Als°Teh°
Fig. 1. Glass-forming region of ternary Ge-Te-A] glass under liquid N 2 quenching, o, glassy; o, crystalline; meshed region:
0022-3093/92/$05.00 © 1992 - Elsevier Science Publishers B.V. All rights reserved
glass-forming region.
178
T. Katsuyama, H. Matsumura / Glass-forming regions of ternary chalcogenide glasses
Table 1 Glass transition temperatures, Tg, and crystallization temperatures, Tx, of G e - T e - A I and G e - T e - S b glasses Composition (mol%)
Tg (°C)
Tx (°C)
GesTeso A115 Te7oA13o Ge2oTeso Ge is.75Tesl.25 Ge i6.25Te83.75 Ge16.sTe82Sbl. 5
172 _+5 170 151 150 141 145
277 + 5 265 227 221 229 229
for binary G e - T e glasses given for comparison. The Tg and Tx values for binary G e - T e glasses in the table are almost the same as those already reported by Savage [5]. This consistency supports the validity of our experimental data for G e - T e A1 glasses. On the other hand, the glass-forming region of ternary G e - T e - S b composition is shown in fig. 2. The experimental data of Tg and Tx for Ge16.sTe82Sba. s glass are also shown in table 1. Figure 1 shows that, for the ternary G e - T e - A I composition, the glassy state can be obtained in a relatively broad region; meaning it is relatively stable. Further, table 1 shows that the Tg values of the G e - T e - A 1 glasses containing 15-30 mol% of A1 are constant (about 170°C). The Tx values are also constant (about 270°C). Therefore, these temperatures show no dependence on the A1 content. For binary G e - T e glasses, the Tg values are 140-150°C and the Tx values are 220-230°C. Therefore, it can be seen that A1 in the G e - T e glasses increases Tg by at least 20°C and Tx by at least 40°C. These temperature increases indicate that ternary G e - T e - A 1 glasses are more stable than binary G e - T e glasses. On the other hand, fig. 2 shows that the glassforming region for G e - T e - S b composition is clearly smaller than that of the G e - T e - A 1 glass system. Further, the G e - T e - S b glass shows no increase of Tg and Tx compared with binary G e Te glasses. Therefore, it is clear that G e - T e - A 1 glasses are more stable than G e - T e - S b glasses. The glass stability of ternary G e - T e - A 1 glasses indicates the possibility of these glasses being used in infrared optical fiber material applications. In particular, it is worth mentioning that a high-speed drawing method has been recently developed, resulting in a successful drawing of a
Te
40?VVV 60 10 20 30 40
0 S bz~T%0
Ge
>
Ge4oTe60
Fig. 2. Glass-forming region of ternary O e - T e - S b glass under liquid N 2 quenching. ©, glassy; o, crystalline; meshed region: glass-forming region.
glass composition with a low Tg value of around 170°C [2]. Therefore, an increase in Tg up to 170°C in the G e - T e - A I glass system suggests the possibility of drawing the glass into a low-loss optical fiber. However, the multiphonon edge will be shifted toward a shorter wavelength region because of the small mass of A1 in the G e - T e - A 1 glass. Therefore, it is preferable to use a glass region with a relatively low A1 content, but with still high Tg and Tx, in realizing an optical fiber with a low loss at around 10 Ixm. In summary, the G e - T e - A 1 glasses show a relatively broad glass-forming region under liquid N 2 quenching. For G e - T e - A 1 glass, glass transition and crystallization temperatures are higher than those of binary G e - T e glass by at least 20°C and 40°C, respectively. On the other hand, the glass-forming region of G e - T e - S b glass is smaller than that of the G e - T e - A 1 glass. The G e - T e - A 1 glass appears to have capabilities applicable for use as infrared optical fiber material because of its stable vitreous state.
References [1] T. Katsuyama and H. Matsumura, Infrared Optical Fibers (Adam Hilger, London, 1989) pp. 212-219. [2] T. Katsuyama and H. Matsumura, Appl. Phys. Lett. 49 (1986) 22. [3] T. Takamori, R. Roy and G.J. McCarthy, Mater. Res. Bull. 5 (1970) 529. [4] S. Iizima, M. Sugi, M. Kikuchi and K. Tanaka, Solid State Commun. 8 (1970) 153. [5] J.A. Savage, J. Mater. Sci. 6 (1971) 964. [6] J.A. Savage, J. Non-Cryst. Solids 11 (1972) 121. [7] S. Bordas, J. Casas-Vazquez, N. Clavaguera and M.T. Clavaguera-Mora, Thermochim. Acta 28 (1979) 387.