- Email: [email protected]
Thermal properties and crosslinking of binary TeO2–Nb2O5 and TeO2–WO3 glasses
LETTER TO THE EDITOR Journal of Non-Crystalline Solids 379 (2013) 177–179
Contents lists available at ScienceDirect
Journal of Non-Crystalline Solids journal homepage: www.elsevier.com/ locate/ jnoncrysol
Letter to the editor
Thermal properties and crosslinking of binary TeO2–Nb2O5 and TeO2–WO3 glasses R. El-Mallawany ⁎ Physics Department, Science College, Northern Borders University, Kingdom of Saudi Arabia
a r t i c l e
i n f o
Article history: Received 17 May 2013 Received in revised form 30 July 2013 Available online 7 September 2013 Keywords: Thermal properties; Tellurite glasses; Crosslink density
a b s t r a c t Binary tellurite glasses in the form (100 − x)TeO2–xAnOm and AnOm = Nb2O5 and WO3 oxides have been prepared by the melt quenching technique and x = 4, 10 mol% for Nb2O5 and 20 mol% WO3. Density and molar volume have been measured and calculated. Differential scanning calorimetric curves of these glasses have been investigated to measure thermal properties of these glasses. The thermal properties were the glass transition temperature Tg (°C), the onset of crystallization temperature Tx (°C) and the glass stability S = (Tx − Tg) (°C). The glass transition temperature has been analyzed according to the average crosslink density that is present in the glass. © 2013 Elsevier B.V. All rights reserved.
Tellurite glasses are promising materials for photonics applications. Tellurite glasses are very interesting glasses because they have unique physical properties [1–14]. The glass transition temperature Tg (°C) and the glass stability S = (Tx − Tg) (°C) are important factors in dealing with glass fiber. The present work focused on the thermal properties of tellurite glass in the binary form and performed the role of the modifiers in tellurite glass. The glass systems (100 − x)TeO2–xAnOm and AnOm = Nb2O5 and WO3 oxides were prepared by mixing specified weights of tellurium oxide (TeO2, Alfa 99%), neobium oxide (Nb2O5 99.99 % Alfa), and tungsten oxide (WO3, BDH, 99.9%) as explained before [15]. The densities of the glass were determined according to the Archimedes principle using toluene as the medium. The glass transition temperature Tg and crystallization onset temperature Tx were measured by using the differential scanning calorimetric (DSC) at a heating rate of 10 °C/min. The glasses were fully transparent and possessed from lime yellowish color for the pure and binary tungsten tellurite glass to be pink for the ternary tellurite glasses. X-ray analysis of the prepared glasses showed no clear or sharp lines, which confirms the amorphous nature of the glass samples investigated. The densities of the glasses are shown in Table. 1. Densities increased from 4.966 g/cm3 of pure TeO2 glass to 5.431 g/cm3 for binary 80TeO2–20WO3, 6.580 g/cm3 for the binary 96TeO2–4Nb2O5, and 6.410 g/cm3 for binary 90TeO2–10Nb2O5,
⁎ Physics Department, Faculty of Science, Menofia University, Egypt. Tel.: + 201221956596. E-mail addresses: [email protected], [email protected]. 0022-3093/$ – see front matter © 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.jnoncrysol.2013.07.037
respectively. Molar volume of the present glass has been calculated according to the relation V M ¼ Mg =ρg
ð1Þ
where Mg is the molecular weight of the glass and can be calculated according to the relation; n o Mg ¼ ð100−xÞ M g ðTeO2 Þ þ xM g ðAn Om Þ =100
ð2Þ
Values of the molar volume have been collected in Table 1. Molar volume changed from 32.14 cm3 for pure TeO2 to 32.05 cm3, 24.90 cm3 and 26.55 cm3 for the substitutions with of 20 mol % WO3, 4 mol% Nb2O5 and 10 mol% Nb2O5, respectively. Fig. 1 represents the DSC curves for pure TeO2 and binary glasses (100 − x)TeO2–xAnOm where AnOm = Nb2O5 and WO3 at heating rate α = 10 K/min. All samples had the same trend and no characteristic feature was observed. Table 1 collected the values of the glass transition temperature Tg, the onset crystallization temperature Tx and the calculated glass stability S for the prepared glasses. The glass transition temperature changed from 325 °C of pure TeO2 to 348 °C, 350 °C and 331 °C for the substitutions with of 20 mol % WO3, 4 mol% Nb2O5 and 10 mol% Nb2O5, respectively. Increase of Tg can be interpreted as increase of the rigidity of the glass; in other words, the change in Tg indicates a change related to the manner in which WO3 and Nb2O5 get arranged in the glass. The onset crystallization temperature Tx were 405 °C of pure TeO2, 461 °C, 480 °C and 465 °C for binary tellurite glasses modified with of 20 mol% WO3, 4 mol% Nb2O5 and 10 mol% Nb2O5, respectively. The glass stability S = (Tx − Tg) has been calculated according to the difference between Tx and Tg and was equal to 80 °C
LETTER TO THE EDITOR 178
R. El-Mallawany / Journal of Non-Crystalline Solids 379 (2013) 177–179
Table 1 Tellurite glass composition, glass density ρg (g/cm3), molar volume VM (cm3), glass transition temperature Tg (°C), onset crystallization temperature Tx (°C), thermal stability S (°C), and average crosslink density nc . Glass composition
ρg (g/cm3)
VM (cm3)
Tg (±1 °C)
Tx (±1 °C)
S (±1 °C)
nc
TeO2 80 TeO2–20 WO3 96 TeO2–4 Nb2O5 90 TeO2–10 Nb2O5
4.966 5.431 6.580 6.410
32.14 32.05 24.90 26.56
325 348 350 331
405 461 480 465
80 113 130 134
2.0 2.0 2.15 2.36
of pure TeO2, 113 °C, 130 °C and 134 °C for the modification of 20 mol% WO3, 4 mol% Nb2O5 and 10 mol% Nb2O5, respectively. Thus among the present glasses, 90TeO2–10Nb2O5 glass has the highest thermal stability which makes it strong against thermal shocks. The quantitative analysis relating the structure parameters on Tg is the average crosslink density was calculated using the relation: X nc ¼
i
xi ðnc Þi ðN c Þi
X
xi ðNc Þi
ð3Þ
i
where x is the mol fraction of component oxide, nc is the cross-link density per cation, Nc is the number of cations per glass formula unit and i denotes the component oxide. The coordination number of C.N.(TeO2) = 4 [16], C.N.(WO3) = 4 [17] and C.N.(Nb2O5) = 6 [16]. The average cross-link density increased from 2.0 pure TeO2 glass and 80TeO2–20WO3 glass to 2.15 and 2.36 for 96TeO2–4Nb2O5 and 90TeO2–10Nb2O5 glasses as shown in Table 1. Finally, it has been concluded that these new glass systems are more linked than the pure TeO2 or 80TeO2–20WO3 glasses and consequently, lead to the observed increase of (Tg) with the mol% of the modifiers. Fig. 2 illustrates the difference between both modifiers in tellurite glass. Due to the difference
Fig. 2. Illustration of WO3 and Nb2O5 in tellurite glasses. (A) TeO2–WO3 with W3+ ion in tetrahedral position. (B) TeO2–Nb2O5 with Nb5+ ion in octahedral position.
in the coordination number of WO3 and of Nb2O5 it is clear that the volume in the binary TeO2–WO3 is larger than the molar volume in binary TeO2–Nb2O5 glass. The study of glass density, molar volume and thermal properties of (100 − x)TeO2–(x)AnOm binary glasses revealed the following conclusions: 1. The density of the pure tellurite glass increased with an increase in mol percentage of 4 and 10 mol% of Nb2O5 than 20 mol% of WO3, 2. Molar volume of pure tellurite glass decreased by modifying it with 4 and 10 mol% of Nb2O5 than 20 mol% WO3. 3. Binary tellurite glass 90TeO2–10Nb2O5 is more stable than binary glasses 80TeO2–20WO3. 4. The average crosslink density of the present glasses indicated that glass of 4 Nb2O5 mol% and also glass of 10 Nb2O5 mol% were higher than average crosslink density of the glass with 20 WO3 mol%. The above results will be gathered with the previous ones [18–22] to analyze the structural changes for tellurite glasses [23].
Acknowledgement The author acknowledges N. Veeraiah, Department of Physics, Acharya Nagarjuna University, India, for his help in illustrating tellurite glasses. References
Fig. 1. DSC curves for pure TeO2 and binary glasses (100 − x)TeO2–xAnOm where AnOm = Nb2O5 and WO3 glasses at heating rate α = 10 K/min.
[1] J. Moraes, J. Nardi, S. Sidel, B. Mantovani, K. Yukimitu, V. Reynoso, L. Malmonge, N. Ghofraniha, G. Ruocco, L. Andrade, S. Lima, J. Non-Cryst. Solids 356 (2010) 2146. [2] A. Mori, J. Ceram. Soc. Jpn. 116 (2008) 1040. [3] D. Chen, Y. Liu, Q. Zhang, Z. Deng, Z. Jiang, Mater. Chem. Phys. 90 (2005) 78. [4] R. El-Mallawany, J. Appl. Phys. 73 (1993) 4878.
LETTER TO THE EDITOR R. El-Mallawany / Journal of Non-Crystalline Solids 379 (2013) 177–179 [5] M.A. Sidkey, R. El-Mallawany, R.I. Nakhla, A. Abd El-Moneim, Phys. Status Solidi A 159 (1997) 397. [6] R.El Mallawany, L.M. Sharaf El-Deen, M.M. Elkholy, J. Mater. Sci. 31 (1996) 6339. [7] H. Moawad, H. Jain, R. El-Mallawany, J. Phys. Chem Solids 70 (2009) 224. [8] R. El-Mallawany, J. Mater. Res. 5 (1990) 2218. [9] K. Selvaraju, K. Marimuthu, J. Alloy Comp. 553 (2013) 273. [10] A.E. Ersundu, M. Çelikbilek, S. Aydin, J. Non-Cryst. Solids 358 (2012) 641. [11] A.A.H. Sidek, S. Rosmawati, B.Z. Azmi, A.H. Shaari, Adv. Cond. Matter Phys. 2013 (2013) 6, http://dx.doi.org/10.1155/2013/783207, (Article ID 783207). [12] Pengfei Wang, Cuicui Wang, Weinan Li, Lu. Min, Bo Peng, J. Non-Cryst. Solids 359 (2013) 5. [13] J. Ozdanova, H. Ticha, L. Tichy, Opt. Mater. 32 (2010) 950. [14] N. Narasimha Rao, I.V. Kityk, V. Ravi Kumar, P. Raghava Rao, B.V. Raghavaiah, P. Czaja, P. Rakus, N. Veeraiah, J. Non-Cryst. Solids 358 (2012) 702.
179
[15] E.F. Lambson, G.A. Saunders, B. Bridge, R.A. El-Mallawany, J. Non-Cryst. Solids 69 (1984) 117. [16] A.F. Walls, Structre of Inorganic Chemistry, 4th ed., Oxford University Press, Oxford, 1975, p. 581. [17] Andreı Mirgorodsky, Maggy Colas, Mikhael Smirnov, Therese Merle-Me jean, Raouf El-Mallawany, Philippe Thomas, J. Solid State Chem. 190 (2012) 45. [18] R.A. El-Mallawany, Infrared Phys 29 (1989) 781. [19] I.Z. Hagar, R. El-Mallawany, M. Poulain, J. Mater. Sci. 34 (1999) 5163. [20] R.A. El-Mallawany, G.A. Saunders, J. Mater. Sci. Lett. 6 (1987) 443. [21] Z.C.K. Bouchaour, M. Poulain, M. Belhadji, I. Hager, R. El-Mallawany, J. Non-Cryst. Solids 351 (2005) 818. [22] R.N. Hampton, W. Hong, G.A. Saunders, R.A. El-Mallawany, J. Non-Cryst. Solids 94 (1987) 307. [23] R. El-Mallawany, in press.
Contents lists available at ScienceDirect
Journal of Non-Crystalline Solids journal homepage: www.elsevier.com/ locate/ jnoncrysol
Letter to the editor
Thermal properties and crosslinking of binary TeO2–Nb2O5 and TeO2–WO3 glasses R. El-Mallawany ⁎ Physics Department, Science College, Northern Borders University, Kingdom of Saudi Arabia
a r t i c l e
i n f o
Article history: Received 17 May 2013 Received in revised form 30 July 2013 Available online 7 September 2013 Keywords: Thermal properties; Tellurite glasses; Crosslink density
a b s t r a c t Binary tellurite glasses in the form (100 − x)TeO2–xAnOm and AnOm = Nb2O5 and WO3 oxides have been prepared by the melt quenching technique and x = 4, 10 mol% for Nb2O5 and 20 mol% WO3. Density and molar volume have been measured and calculated. Differential scanning calorimetric curves of these glasses have been investigated to measure thermal properties of these glasses. The thermal properties were the glass transition temperature Tg (°C), the onset of crystallization temperature Tx (°C) and the glass stability S = (Tx − Tg) (°C). The glass transition temperature has been analyzed according to the average crosslink density that is present in the glass. © 2013 Elsevier B.V. All rights reserved.
Tellurite glasses are promising materials for photonics applications. Tellurite glasses are very interesting glasses because they have unique physical properties [1–14]. The glass transition temperature Tg (°C) and the glass stability S = (Tx − Tg) (°C) are important factors in dealing with glass fiber. The present work focused on the thermal properties of tellurite glass in the binary form and performed the role of the modifiers in tellurite glass. The glass systems (100 − x)TeO2–xAnOm and AnOm = Nb2O5 and WO3 oxides were prepared by mixing specified weights of tellurium oxide (TeO2, Alfa 99%), neobium oxide (Nb2O5 99.99 % Alfa), and tungsten oxide (WO3, BDH, 99.9%) as explained before [15]. The densities of the glass were determined according to the Archimedes principle using toluene as the medium. The glass transition temperature Tg and crystallization onset temperature Tx were measured by using the differential scanning calorimetric (DSC) at a heating rate of 10 °C/min. The glasses were fully transparent and possessed from lime yellowish color for the pure and binary tungsten tellurite glass to be pink for the ternary tellurite glasses. X-ray analysis of the prepared glasses showed no clear or sharp lines, which confirms the amorphous nature of the glass samples investigated. The densities of the glasses are shown in Table. 1. Densities increased from 4.966 g/cm3 of pure TeO2 glass to 5.431 g/cm3 for binary 80TeO2–20WO3, 6.580 g/cm3 for the binary 96TeO2–4Nb2O5, and 6.410 g/cm3 for binary 90TeO2–10Nb2O5,
⁎ Physics Department, Faculty of Science, Menofia University, Egypt. Tel.: + 201221956596. E-mail addresses: [email protected], [email protected]. 0022-3093/$ – see front matter © 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.jnoncrysol.2013.07.037
respectively. Molar volume of the present glass has been calculated according to the relation V M ¼ Mg =ρg
ð1Þ
where Mg is the molecular weight of the glass and can be calculated according to the relation; n o Mg ¼ ð100−xÞ M g ðTeO2 Þ þ xM g ðAn Om Þ =100
ð2Þ
Values of the molar volume have been collected in Table 1. Molar volume changed from 32.14 cm3 for pure TeO2 to 32.05 cm3, 24.90 cm3 and 26.55 cm3 for the substitutions with of 20 mol % WO3, 4 mol% Nb2O5 and 10 mol% Nb2O5, respectively. Fig. 1 represents the DSC curves for pure TeO2 and binary glasses (100 − x)TeO2–xAnOm where AnOm = Nb2O5 and WO3 at heating rate α = 10 K/min. All samples had the same trend and no characteristic feature was observed. Table 1 collected the values of the glass transition temperature Tg, the onset crystallization temperature Tx and the calculated glass stability S for the prepared glasses. The glass transition temperature changed from 325 °C of pure TeO2 to 348 °C, 350 °C and 331 °C for the substitutions with of 20 mol % WO3, 4 mol% Nb2O5 and 10 mol% Nb2O5, respectively. Increase of Tg can be interpreted as increase of the rigidity of the glass; in other words, the change in Tg indicates a change related to the manner in which WO3 and Nb2O5 get arranged in the glass. The onset crystallization temperature Tx were 405 °C of pure TeO2, 461 °C, 480 °C and 465 °C for binary tellurite glasses modified with of 20 mol% WO3, 4 mol% Nb2O5 and 10 mol% Nb2O5, respectively. The glass stability S = (Tx − Tg) has been calculated according to the difference between Tx and Tg and was equal to 80 °C
LETTER TO THE EDITOR 178
R. El-Mallawany / Journal of Non-Crystalline Solids 379 (2013) 177–179
Table 1 Tellurite glass composition, glass density ρg (g/cm3), molar volume VM (cm3), glass transition temperature Tg (°C), onset crystallization temperature Tx (°C), thermal stability S (°C), and average crosslink density nc . Glass composition
ρg (g/cm3)
VM (cm3)
Tg (±1 °C)
Tx (±1 °C)
S (±1 °C)
nc
TeO2 80 TeO2–20 WO3 96 TeO2–4 Nb2O5 90 TeO2–10 Nb2O5
4.966 5.431 6.580 6.410
32.14 32.05 24.90 26.56
325 348 350 331
405 461 480 465
80 113 130 134
2.0 2.0 2.15 2.36
of pure TeO2, 113 °C, 130 °C and 134 °C for the modification of 20 mol% WO3, 4 mol% Nb2O5 and 10 mol% Nb2O5, respectively. Thus among the present glasses, 90TeO2–10Nb2O5 glass has the highest thermal stability which makes it strong against thermal shocks. The quantitative analysis relating the structure parameters on Tg is the average crosslink density was calculated using the relation: X nc ¼
i
xi ðnc Þi ðN c Þi
X
xi ðNc Þi
ð3Þ
i
where x is the mol fraction of component oxide, nc is the cross-link density per cation, Nc is the number of cations per glass formula unit and i denotes the component oxide. The coordination number of C.N.(TeO2) = 4 [16], C.N.(WO3) = 4 [17] and C.N.(Nb2O5) = 6 [16]. The average cross-link density increased from 2.0 pure TeO2 glass and 80TeO2–20WO3 glass to 2.15 and 2.36 for 96TeO2–4Nb2O5 and 90TeO2–10Nb2O5 glasses as shown in Table 1. Finally, it has been concluded that these new glass systems are more linked than the pure TeO2 or 80TeO2–20WO3 glasses and consequently, lead to the observed increase of (Tg) with the mol% of the modifiers. Fig. 2 illustrates the difference between both modifiers in tellurite glass. Due to the difference
Fig. 2. Illustration of WO3 and Nb2O5 in tellurite glasses. (A) TeO2–WO3 with W3+ ion in tetrahedral position. (B) TeO2–Nb2O5 with Nb5+ ion in octahedral position.
in the coordination number of WO3 and of Nb2O5 it is clear that the volume in the binary TeO2–WO3 is larger than the molar volume in binary TeO2–Nb2O5 glass. The study of glass density, molar volume and thermal properties of (100 − x)TeO2–(x)AnOm binary glasses revealed the following conclusions: 1. The density of the pure tellurite glass increased with an increase in mol percentage of 4 and 10 mol% of Nb2O5 than 20 mol% of WO3, 2. Molar volume of pure tellurite glass decreased by modifying it with 4 and 10 mol% of Nb2O5 than 20 mol% WO3. 3. Binary tellurite glass 90TeO2–10Nb2O5 is more stable than binary glasses 80TeO2–20WO3. 4. The average crosslink density of the present glasses indicated that glass of 4 Nb2O5 mol% and also glass of 10 Nb2O5 mol% were higher than average crosslink density of the glass with 20 WO3 mol%. The above results will be gathered with the previous ones [18–22] to analyze the structural changes for tellurite glasses [23].
Acknowledgement The author acknowledges N. Veeraiah, Department of Physics, Acharya Nagarjuna University, India, for his help in illustrating tellurite glasses. References
Fig. 1. DSC curves for pure TeO2 and binary glasses (100 − x)TeO2–xAnOm where AnOm = Nb2O5 and WO3 glasses at heating rate α = 10 K/min.
[1] J. Moraes, J. Nardi, S. Sidel, B. Mantovani, K. Yukimitu, V. Reynoso, L. Malmonge, N. Ghofraniha, G. Ruocco, L. Andrade, S. Lima, J. Non-Cryst. Solids 356 (2010) 2146. [2] A. Mori, J. Ceram. Soc. Jpn. 116 (2008) 1040. [3] D. Chen, Y. Liu, Q. Zhang, Z. Deng, Z. Jiang, Mater. Chem. Phys. 90 (2005) 78. [4] R. El-Mallawany, J. Appl. Phys. 73 (1993) 4878.
LETTER TO THE EDITOR R. El-Mallawany / Journal of Non-Crystalline Solids 379 (2013) 177–179 [5] M.A. Sidkey, R. El-Mallawany, R.I. Nakhla, A. Abd El-Moneim, Phys. Status Solidi A 159 (1997) 397. [6] R.El Mallawany, L.M. Sharaf El-Deen, M.M. Elkholy, J. Mater. Sci. 31 (1996) 6339. [7] H. Moawad, H. Jain, R. El-Mallawany, J. Phys. Chem Solids 70 (2009) 224. [8] R. El-Mallawany, J. Mater. Res. 5 (1990) 2218. [9] K. Selvaraju, K. Marimuthu, J. Alloy Comp. 553 (2013) 273. [10] A.E. Ersundu, M. Çelikbilek, S. Aydin, J. Non-Cryst. Solids 358 (2012) 641. [11] A.A.H. Sidek, S. Rosmawati, B.Z. Azmi, A.H. Shaari, Adv. Cond. Matter Phys. 2013 (2013) 6, http://dx.doi.org/10.1155/2013/783207, (Article ID 783207). [12] Pengfei Wang, Cuicui Wang, Weinan Li, Lu. Min, Bo Peng, J. Non-Cryst. Solids 359 (2013) 5. [13] J. Ozdanova, H. Ticha, L. Tichy, Opt. Mater. 32 (2010) 950. [14] N. Narasimha Rao, I.V. Kityk, V. Ravi Kumar, P. Raghava Rao, B.V. Raghavaiah, P. Czaja, P. Rakus, N. Veeraiah, J. Non-Cryst. Solids 358 (2012) 702.
179
[15] E.F. Lambson, G.A. Saunders, B. Bridge, R.A. El-Mallawany, J. Non-Cryst. Solids 69 (1984) 117. [16] A.F. Walls, Structre of Inorganic Chemistry, 4th ed., Oxford University Press, Oxford, 1975, p. 581. [17] Andreı Mirgorodsky, Maggy Colas, Mikhael Smirnov, Therese Merle-Me jean, Raouf El-Mallawany, Philippe Thomas, J. Solid State Chem. 190 (2012) 45. [18] R.A. El-Mallawany, Infrared Phys 29 (1989) 781. [19] I.Z. Hagar, R. El-Mallawany, M. Poulain, J. Mater. Sci. 34 (1999) 5163. [20] R.A. El-Mallawany, G.A. Saunders, J. Mater. Sci. Lett. 6 (1987) 443. [21] Z.C.K. Bouchaour, M. Poulain, M. Belhadji, I. Hager, R. El-Mallawany, J. Non-Cryst. Solids 351 (2005) 818. [22] R.N. Hampton, W. Hong, G.A. Saunders, R.A. El-Mallawany, J. Non-Cryst. Solids 94 (1987) 307. [23] R. El-Mallawany, in press.