Structural change of OH-free fused quartz tube by blowing with hydrogen oxygen flame

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1 Journal of Non-Crystalline Solids 333 (4) Structural change of OH-free fused quartz tube by blowing with hydrogen oxygen flame Nobu Kuzuu a,b, *, Yosuke Kokubo c, Tsutomu Nishimura c, Izumi Serizawa c, Ling-Hai Zeng a, Kenji Fujii a, Makoto Yamaguchi d, Kazuya Saito d, Akira J. Ikushima d a Department of Applied Physics, University of Fukui, 3-9- Bunkyo, Fukui-Shi, Fukui, Japan b Fukui Prefecture Collaboration of Regional Entities for the Advancement of Technology Corporation, Kita Inada, 6 Kawai Washizuka-Cho, Fukui-Shi, 9- Fukui, Japan c ORC Manufacturing Company Ltd., 4896 Tamagawa, Chino-shi 39-, Nagano, Japan d Research Center for Advanced Photon Technology, Toyota Technological Institute, -- Hisakata, Tempaku-ku, Nagoya, Japan Received 9 July 3; received in revised form 7 September 3 Abstract The effect of blowing with a hydrogen oxygen flame on the structure of an OH-free fused quartz tube was studied by microscopic spectroscopy. The number of OH groups increased within lm from the outside surface (OSS). The peak decomposition of the IR absorption at around 36 cm showed that most OH structures were Ôfree BSiAOH without the hydrogen bond, and H O molecules were also distributed throughout the cross section. The distribution of the fictive temperature, T F, in the cross section was measured from the peak position of infrared absorption at cm. T F before blowing was 4 K, which is near the strain point, except in the region within lm from the OSS, where T F steeply decreases approaching the OSS. After blowing, the values of T F became greater than those before blowing, increasing steeply from the OSS and having a maximum at lm. The steep change near the OSS must be caused by the shorter structural relaxation time due to the BSiAOH introduced by blowing and H O vapor in the flame. The distribution of the intensities of Raman bands at 495 (D ) and 66 cm (D ) derived from the planar fourand three-member rings was also measured. Ó 3 Elsevier B.V. All rights reserved. PACS: 6.43Fs; 7.4Pg. Introduction * Corresponding author. Address: Department of Applied Physics, University of Fukui, 3-9- Bunkyo, Fukui-Shi, Fukui, Japan. Tel./fax: address: kuzuu@polymer.apphy.fukui-u.ac.jp (N. Kuzuu). Vitreous silica (v-sio ) is a high-purity amorphous silicon dioxide (SiO ). This material can be divided into synthetic fused silica (SFS) produced from liquid material in the vapor or liquid phase, and fused quartz (FQ) produced by melting natural quartz powder []. FQ can be further divided into two categories []. One is type-i FQ produced by melting quartz powder with an electric furnace or with an arc plasma, which contains, at most, 4 ppm of OH. The other is type-ii FQ produced by melting quartz powder in a hydrogen oxygen flame, which contains 6 ppm of OH. In the last few decades, the structures and properties of SFS have been studied extensively [], stimulated by the development of optical telecommunication and lithography technologies for ultralarge-scale integrated circuits (ULSI). In these applications, SFS is used in optical fibers, photomasks and lenses for step-and-repeat projectors (steppers) [ 4]. FQ is still an important material in industrial applications due to its high heat-resistivity and extremely low content of metallic impurities []. FQ, however, is inappropriate for optical applications such as in lenses and prisms because it contains defects such as bubbles, inclusions, striae, and granular structure []. In addition to such semi-macroscopic defects, FQ has absorption bands due to point defects in the ultraviolet (UV) region of K 3 nm []. A well-known absorption band in FQ exists at 5 ev, called the B band [3 5]. At least two kinds of B bands are known [3,4]. One is the B a band at 5. ev with a full-width at half maximum (FWHM) -393/$ - see front matter Ó 3 Elsevier B.V. All rights reserved. doi:.6/j.jnoncrysol.3..4

2 6 N. Kuzuu et al. / Journal of Non-Crystalline Solids 333 (4) 5 3 of.3 ev caused by a neutral oxygen vacancy. The other B b band is at 5.5 ev with FWHM of.48 ev, whose origin is still under debate. The properties of the B b band are affected by its surroundings. For example, the B b band in type-ii FQ can be annealed out in atmospheric ambient while that in type-i FQ cannot [6]. In a previous paper [6], we proposed a model based on the assumption that the B b band is caused by twofoldoxygen-coordinated silicon [TOCS(@Si:)]. The difference in the annealing properties of the B b bands in type-i and type-ii FQ could be derived from the effect of BSiAOH which coordinates with the TOCS [6]; the B b band in type-ii FQ is coordinated by two BSiAOH s, while that in type-i FQ has no such coordinated BSiAOH. Although the optical properties of FQ are inferior to those of SFS, its thermal resistivity is better than that of SFS; the viscosity of FQ is greater than that of SFS at the same temperature and OH content [7], and thermal expansivity is low [8]. Utilizing these properties, FQ is used as a heat-resistant material free of contaminants, such as for the inner tube of a furnace used in impurity diffusion and oxidation processes to produce semiconductor devices, and the bulb of a high-voltage discharge lamp. Such items are fabricated by blowing a FQ tube with a hydrogen oxygen flame. By blowing, the structure of v-sio may change, and the amount of structural change could be greater near the surface compared to the inner part. In fact, such a structural change has been observed in an SFS block heat treated in an electric furnace; an SFS block containing approximately 5 ppm of OH decreased by up to 7 ppm within 5 cm from the surface after heating at 6 C for h [9]. In addition to the decrement of the OH content, absorption bands due to defect structures were induced. Such a structural change should affect the characteristics of the product. By blowing a FQ tube, structural change should also proceed because H O molecules, which can react with the silica glass network at a high-temperature, are produced in the flame. We previously studied [] the effect of blowing an OH-free FQ tube on the structure, and found that hydroxyl groups are produced within lm from the outside surface of the tube. In the previous paper [], we determined only total hydroxyl content. For studying the creation mechanism of hydroxyl groups in detail, we analyzed in this study the blowing-induced absorption spectra of OH by peak decomposition. We also measured the distribution of the fictive temperature in the cross section of the OH-free FQ tube blown with a hydrogen oxygen flame.. Experimental procedure A FQ tube made of type-i FQ, GE4, was blown into a spherical shape using a hydrogen oxygen flame and a glass lathe, as shown in Fig.. During the blowing process, nitrogen gas was introduced into the tube which was shaped spherically using a carbon tool []. Samples were cut from the part indicated in Fig. and the two facing surfaces were polished;.5-mm-thick samples were prepared for infrared (IR) and Raman spectroscopic measurement, and 3-mm-thick ones were prepared for the UV absorption measurement. IR spectra were measured using a Fourier transform infrared (FTIR) spectrophotometer with a microscope measurement unit every lm of the cross section of the portion marked in Fig.. OH content was determined from the peak intensity of the absorption peak at 367 cm using an absorption coefficient of 77.5 L/ mol cm []. The absorption peak was decomposed into several Gaussian bands for the analysis of the form of the hydroxyl groups. Fictive temperature was determined from the peak position of an absorption peak at cm []. Raman spectra were measured using a Raman spectrophotometer with an Ar þ ion laser at a wavelength of 54.5 nm; this spectrophotometer has a spatial resolution of approximately lm. UV spectra were measured using a microscopic UV visible spectrophotometer. 3. Results Fig.. Blowing of the fused quartz tube. 3.. Change of hydroxyl group upon blowing IR absorption spectra of hydroxyl groups at several points in the cross section of the blown tube are shown in Fig.. The position in the cross section is represented by the distance x from the outside surface (OSS). The distribution of OH content before and after blowing are shown in Fig. 3. The OH content at x ¼ lm is approximately 4 ppm and it decreases up to x

3 N. Kuzuu et al. / Journal of Non-Crystalline Solids 333 (4) µm Wavenumber (cm - ) 3 Fig.. Absorption spectra of OH near 36 cm after blowing. The numbers with the curves indicate the measurement position from the outside surface in units of micrometers. OH Content (ppm) 4 3 Blown As-recieved (a) As-recieved Wavenumber (cm - ) (b) Blown Wavenumber (cm - ) 3 3 Fig. 4. Examples of peak decomposition of OH absorption lm from the outside surface before (a) and after (b) blowing. 3 Distance from Outsude Surface (µm) Fig. 3. Distribution of the OH content in the cross section of fused quartz tube before and after blowing. lm. The OH content begins to increase again at x 3 lm [3 lm from the inside surface (ISS)]. With blowing, OH must diffuse into the inner part of the material. To clarify the diffusion mechanism of OH, we analyzed the OH absorption by Gaussian peak decomposition. An example of peak decomposition is shown in Fig. 4. Although the absorption components of OH are not exactly Gaussian [3], we used Gaussian fitting because these components are sufficiently similar to the Gaussian. The peak positions and FWHM shown in Table were determined so as to reproduce all absorption spectra that had been measured in this study. Each absorption component can be assigned to a form of the hydroxyl group such as free BSiAOH, hydrogenbonded OH or H O molecule. The absorption bands at 36, 366 and 369 cm are due to free BSiAOH [3]. The 355 cm band is derived from hydrogen-bonded OH [3]. The absorption bands at 35 and 346 cm are derived from H O molecules [3]. The 38 cm band is reported to be observed in a sample which contains many H O molecules [3]. We assumed the existence of an absorption component at 374 cm whose origin is unknown. This component was required Table Absorption components used for the peak decomposition of the OH absorption near 36 cm Peak (cm ) FWHM (cm ) Origin 35 H O H O 355 H-bonded 36 9 Free Free Free 374 Unknown 38 H O related to reproduce the shoulder at 374 cm in Fig. 4(b) and the absorption spectrum of the as-received sample with an extremely small amount of OH shown in Fig. 4(a). The distribution of the peak intensities of the OH components in the blown sample is shown in Fig. 5. Fig. 5(a) shows the distribution of free BSiAOH, in which the distributions of three components resemble each other. As seen in Fig. 5(a), most hydroxyl groups that increased near the OSS upon blowing is free BSiAOH. The amount of free BSiAOH is also increased near the ISS. The amount of hydrogen-bonded OH increased both near the OSS and the ISS. The intensity of the unknown band at 374 cm also increased near the OSS. Although the intensities of absorption bands at 346 and 38 cm increase near the OSS, that of the 35 cm band decreases. This could be due to error in drawing the baseline because the intensity of this band is

4 8 N. Kuzuu et al. / Journal of Non-Crystalline Solids 333 (4) (a) Blown Free OH 36 cm cm cm (b) (c) 355 cm - (H-bonded OH) 374 cm - (Unknown) H O related 35 cm cm - 38 cm - 3 Fig. 5. Distribution of the intensities of the OH bands after blowing: (a) free OH, (b) hydrogen-bonded OH at 355 cm and an unknown 374 cm band, and (c) H O-related bands... (a)as-recieved Free OH 36 cm cm cm (b) 355 cm - (H-bonded OH) 374 cm - (Unknown) (c) H O related 35 cm cm - 38 cm - 3 Distance from Outside Surface (Pm) Fig. 6. Distribution of the OH bands before blowing: (a) free OH, (b) hydrogen-bonded OH at 355 cm and an unknown 374 cm band, and (c) H O-related bands. extremely weaker than the peak intensity of the absorption spectrum near the OSS and exist at the far from the absorption peak. The as-received tube also has the hydroxyl group, as shown in Fig. 4. The distribution of each component is shown in Fig. 6. In this sample, the amount of free BSiAOH is quite small and the intensities of the H O- related bands are almost the same order as that of the free BSiAOH band. These values are almost constant throughout the cross section except for the free BSiAOH near the ISS; it decreases a little near the ISS. 3.. Distribution of fictive temperature Agarwal et al. [] found that the fictive temperature T F (K) of v-sio can be determined from the peak position m (cm ) of IR absorption at 6 cm, irrespective of the type of v-sio, from T F ¼ 4389: m 8:64 : ðþ Since the fictive temperature is sensitive to the peak position, the peak position was determined by fitting the observed data with the second-order curve within approximately 4 cm around the peak to avoid the error derived from the discrete value of the wave number in the measurement. The distributions of the fictive temperature in the cross section before and after blowing are shown in Fig. 7. The fictive temperature in the as-received tube is approximately constant at 4 K, which is near the strain point 4 K of type-i FQ []. The fictive temperature decreases steeply towards the OSS, and T F is 8 K at x ¼ lm. In the blown tube, the fictive temperature is 4 K at x ¼ lm and it increases towards the bulk. The profile has a maximum, 66 K,

5 N. Kuzuu et al. / Journal of Non-Crystalline Solids 333 (4) Fictive Temperature (K) Blown As-recieved 3 Distance from outside surface (µm) Intensity (arb.units) (a) As-Recieved D D 3 Distance from outside surface (µm) Fig. 7. Distribution of the fictive temperature in the cross section before and after blowing. Intensity (arb.units) ω 3 D D Intensity (arb.units) (b) Blown D D 3 Distance from outside surface (µm) Raman Shift (cm - ) Fig. 9. Distribution of the Raman bands D and D before blowing. Fig. 8. An example of the Raman spectrum; measured at as-received sample at x lm. at x lm, decreases up to x lm, and becomes approximately constant, 55 K, until the ISS. Fig. 8 shows an example of the Raman spectrum. Fig. 9 shows the distribution of the area intensities of the Raman bands at 495 and 66 cm, called the D and D bands. These bands are derived from planar fourand three-member rings, respectively [4]. Galeener showed that the fictive temperature is determined by the area intensities of these Raman bands [4]. Details will be described in Section Discussion 4.. Creation mechanism of hydroxyl group Excess H O molecules are introduced upon blowing, as seen in Fig. 5(c). The intensities of H O-related 346 and 8 cm bands decrease with increasing x near the OSS. This decrement indicates that the H O molecules diffuse into the glass network. Some H O molecules can diffuse directly, conserving their molecular structure, but most molecules must diffuse by reacting with the SiO glass network: BSiAOASiB þ H O BSiAOH HOASiB: ðþ By repeated reaction, BSiAOH and H O diffuse into the glass network. In this reaction, some H O molecules must remain after the material is cooled to room temperature. As a result, the distribution of H O shown in Fig. 5(c) will remain the same. Through this process, the distributions of free BSiAOH and H O arise. Some BSiAOH will combine to oxygen atoms in the framework of the SiAOASi structure; this must be the origin of the hydrogen-bonded OH shown in Fig. 5(b). One might consider that the dependence of the intensities of H O-related bands on the decrease of x indicates the diffusion of the H O molecules while conserving their molecular form. As shown in Fig., however, free BSiAOH also has a similar x dependence as that of H O in the region of x ¼ 34 lm. This suggests that most H O molecules diffuse through reaction (). In the glass-blowing process, the hydrogen oxygen flame contains a stoichiometrically excess amount of hydrogen. Therefore, BSiAOH should also be produced by the reaction of hydrogen and BSiAOASiB as BSiAOASiB þ H BSiAOH HASiB: ð3þ Although some H molecules could diffuse through the repetition of reaction (3), most H molecules diffuse retaining their molecular form because the molecular size is sufficiently small to diffuse directly into the glass network. Although H and BSiAH content might be determined by the Raman peaks at 4 and cm, respectively [6], we could not detect them.

6 N. Kuzuu et al. / Journal of Non-Crystalline Solids 333 (4) Blown Free OH H Or elated Fig.. Distributions of free OH and H O in the blown tube. Intensities of OH-related bands for the as-received tube are weak, and are almost constant throughout the cross section, as shown in Fig. 6. In this sample, the relative intensities of H O-related components to free BSiAOH are stronger compared to those of the blown tube. This might be due to the adsorbed H O molecules on the polished surface (PS) which was formed for the measurement. During the polishing process, silanol groups must be introduced on the PS, and H O molecules must be adsorbed on these silanol groups. If the observed absorption is derived from such OH structures created on the PS, the absorption intensity should not be proportional to the thickness; the numbers of surface silanol groups and adsorbed H O molecules depend on the surface situation, i.e., the polishing condition and the environment of sample storage. Hence we compared the absorption spectra of three samples: the originally polished sample with a thickness of.5 mm, and newly polished samples.56- and 4.7-mm-thick. The ratio of OH absorption intensities of these samples was approximately ::4, if all of these absorptions are derived from the silanol groups existing in the bulk, the ratio must become approximately ::. The discrepancy of these ratios suggests that the contribution of the OH structures on the surface is prominent in the absorption spectrum of the as-received sample. Since the amount of OH in the as-received tube is almost constant throughout the cross section, the absorption measured through the tube cross section should provide additional insight into the origin of the OH. Fig. shows the infrared absorption spectrum observed for the tube cross section without using the microscope unit. For peak decomposition of the absorption spectrum in Fig., an absorption component at 3 cm with FWHM of 5 cm is needed in place of the 35 cm band. The differences in the peak position and the width might be due to the difference in the baseline between samples, because the surface of the sample in Fig. is curved while that in Fig. 4(a) is flat. The intensities of free- and hydrogen-bonded OH bands in Fig. are very weak compared to those in Fig. 4(a). This suggests that almost all free BSiAOHs in Fig. 4(a) exist on the surface. The intensities of H O components in both Figs. 4(a) and are almost the same as each other. This seems to suggest that most H O molecules exist in the bulk. However, such a situation is improbable because H O molecules should exist with BSiAOH structures in the bulk; H O molecules can react easily with BSiAOASiB bonds in the glass network during the drawing process, by reaction (). Therefore, most OH structures must exist on the PS. In the previous investigations, we studied the characteristics of the UV absorption bands in FQ [5,6]. FQ has an absorption band near 5 ev called the B band. FQ used in the present study is of a similar type to that used previously [6], i.e., FQ produced by melting in an electric furnace. The only difference is that the present tube is formed directly after melting the raw material. The type-i FQ has two kinds of B bands. One is the B a band whose peak position is at 5. ev with FWHM of.3 ev [5]. This band is derived from the BSiSiB structure called ODC(II) [4,6], where Ô indicates the oxygen vacancy formed by removing the oxygen atom from the BSiAOASiB structure. ODC(II) always coexists with the BSiASiB structure called ODC(I), which causes the absorption band at 7.6 ev [4]. These defects are in equilibrium with each other [7,7]. Hereafter, we will call both ODC(I) and ODC(II) ODC, denoted by the structure BSiSiB. The other type of B band is the B b band whose peak position is at 5.5 ev with FWHM of.48 ev [5]. A number of models for the origin of the B b band has been proposed: [4] ODC(II), twofold-oxygen-coordinated silicon [TOCS(@Si:)], and Ge-related oxygen vacancies such as BGeSiB. We assumed, in previous papers [5,6], that the origin of B b is TOCS. During the blowing process, H O and H molecules must react with ODC or TOCS as BSi SiB þ H O! BSiAOH HASiB ð4þ or =Si: + H O.. 4 =Si Wavenumber (cm - ) 3 3 Fig.. OH absorption of as-received sample measured throughout the cross section of the tube. OH : ð5þ H

7 N. Kuzuu et al. / Journal of Non-Crystalline Solids 333 (4) µm µm µm 33 µm Photon Enegy (ev) Fig.. UV absorption spectra at 5,,, and 33 lm from the outside surface. Utilizing these reactions, B bands near the OSS must be bleached. In fact, as shown in Fig., the absorption near 5 ev was bleached near the OSS (x ¼ 3 lm). The absorption intensity at 5 ev near the ISS [x ¼ 33 lm ( lm from ISS)] also partly decreased compared to the inner part of the cross section (x ¼ lm). This may correspond to the increment of the hydroxyl content near the ISS. 4.. Fictive temperature distribution Fictive temperature of the as-received tube is approximately constant except near the OSS where the fictive temperature is lower than in the other parts, as shown in Fig. 7. The FQ tube had been quenched to a lower temperature than the annealing point directly after drawing. By this quenching process, the structure could be frozen at that of the temperature of 4 K because the relaxation time at high-temperature is short enough to relax the structure during drawing. Another possibility is that the tube had been heat treated at 43 K after drawing; most silica glass products are heat treated at 43 K to remove strain. The glass structure could relax faster on the surface than in the bulk. Agarwal et al. showed the faster relaxation on the silica glass surface by measuring the rate of the change of the peak positions at and cm in IR absorption and reflection spectra [], respectively. The cm peak is the overtone of the cm peak which is caused by the transverse optic components of the fundamental antisymmetric stretching vibration []. Both peaks can be related to the fictive temperature, as described in Section 3. for the cm band. The change of the cm absorption peak is an index of the structural relaxation in the bulk and that of the cm reflection peak is an index of the surface relaxation. This must be the cause of the lower fictive temperature near the surface, because the structure can relax to a lower fictive temperature during cooling. Tomozawa et al. [8] showed that the relaxation time of the surface structure becomes shorter due to tensile stress and longer due to compressive stress. Because of the shrinkage caused by cooling, tensile and compressive stresses would be induced on the OSS and the ISS, respectively. With tensile stress, the structure near the OSS relaxes more easily, and the fictive temperature becomes lower than that in the bulk. On the ISS, on the other hand, compressive stress slows the structural relaxation and the fictive temperature should remain the same as that in the bulk. As a result, the fictive temperature of the as-received sample decreased only near the OSS. The fictive temperatures of the blown tube are greater than those of the as-received tube. This is reflected by the thermal history during blowing; the fictive temperature is an increasing function of x in the region x ¼ 9 lm, and becomes a maximum at x lm. Then the fictive temperature decreases and becomes constant at x J lm except at the ISS at which the fictive temperature is less than the bulk value. This distribution can be reflected by the temperature distribution during blowing. The temperature is a decreasing function of x when the outside of the tube is fused by the flame. The increments of the fictive temperature up to the maximum point is reflected by the effect of BSiAOH and H O vapor on structural relaxation during the cooling process; this part corresponds to the part in which OH is introduced by blowing. In addition to the surface relaxation mentioned above, increments of the OH content and the vapor atmosphere accelerate the structural relaxation. In general, the structural relaxation time decreases markedly with increasing OH content. For instance, the structural relaxation time observed by the D and D Raman bands of v-sio containing ppm of OH is three orders greater than that in OH-free v-sio [4]. In addition to the effect of OH, H O vapor promotes the relaxation of the surface structure [9]. Near the ISS, on the other hand, the fictive temperature does not decrease except at outermost point. The decrement of the fictive temperature at the ISS must be due to the shorter relaxation time compared to that in bulk; the structural relaxation time at the surface is shorter than that in bulk even under compressive stress [8], and the SiAOH introduced near the ISS (Fig. 3) also make the relaxation time shorter. In addition to the effect of shorter relaxation time, cooling effect of N gas flowing in the tube make the fictive temperature lower Comparison of the fictive temperature and the Raman bands D and D Galeener [4] showed that the relationship between the area intensities of D and D bands and fictive

8 N. Kuzuu et al. / Journal of Non-Crystalline Solids 333 (4) 5 3 ln (Intensity) D D As-recieved Blown /T F (K - ) Fig. 3. Arrhenius plot of the area intensities of Raman bands D and D verses the fictive temperature determined from the position of the IR peak near cm, using Eq. (). temperature follows an Arrhenius plot. However, the accuracy of the fictive temperatures determined from the Raman bands is worse than that obtained from the IR band near cm []. Mikkelsen and Galeener [] represented the peak intensity by the percent area of the total first-order spectrum. Since the baseline of the Raman spectra near the surface was somewhat different from that of the bulk in the present case, we normalized the peak intensities by the area of the peak at 8 cm. The relationship between the intensity and the fictive temperature should be calibrated anew for the present data, but we have not yet done so. Fig. 3 shows the Arrhenius plot of the area intensities of D and D versus the fictive temperature evaluated from the IR peak position. Since the observed points between the IR and Raman spectra do not correspond with each other, the profile of the fictive temperatures obtained from IR peaks in Fig. 7 were approximated by the ninth-order polynomial. The plots for D of the blown tube and of the as-received tube are distributed with relatively small dispersion along the lines indicated in the figure, but the plots for D in the as-received tube fall above the line on average. As for D, its dispersion is greater at lower fictive temperatures. From the slope of the line in Fig. 3, the activation energies of D and D are obtained to be.4 and.76 ev, respectively. The activation energies obtained by Galeener [4] for D and D are.4 ±.4 and.4 ±. ev, respectively. Although the activation energies for D agree with each other, the present value for D is considerably smaller than the Galeener s value. The reason for the discrepancy in the activation energies of D between the present study and Galeener s work cannot be explained at the present stage. Further examination is necessary after calibrating the relationship between the intensities of Raman bands and the fictive temperature. 5. Summary and conclusion Structural change in the cross section of an OH-free FQ tube upon blowing with a hydrogen oxygen flame was studied by microscopic spectroscopy. OH content increased within lm from the outside surface which had been fused by the flame. The result of peak decomposition of the IR absorption band corresponding to OH indicated that most of the OH created from the surface upon blowing was free BSiAOH, but some H O molecules were generated. This suggests that most H O molecules diffuse through the equilibrium reaction of H O molecules and BSiAOASiB bonds. The fictive temperature distribution in the cross section was determined from the IR absorption peak position at cm. The fictive temperature of the as-received tube was approximately 4 K except near the outside surface. Upon blowing, the fictive temperature increased, and the distribution curve exhibited a maximum at lm from the outside surface. This is caused by the temperature distribution during blowing and the effects of BSiAOH and the H O vapor on accelerating the structural relaxation near the surface. We also measured the distribution of the intensities of Raman bands D (495 cm ) and D (66 cm ). These intensities show a linear relationship with fictive temperature in the Arrhenius plot. This relationship was obtained by comparing the fictive temperature determined using IR spectra. The fictive temperature obtained agreed well with that obtained using IR spectra, at least for the blown tube. References [] R. Br uckner, J. Non-Cryst. Solids 5 (97) 3. [] H. Kawazoe, K. Awazu, Y. Ohki, N. Kuzuu, S. Todoroki, A. Hayashi, H. Fukuda (Eds.), Hishoushitsu Shirika Zairyou Ouyou Handobukku (Handbook for Application of Amorphous Silica), Realize, Tokyo, 999. [3] D.L. Griscom, J. Ceram. Soc. Jpn. 99 (99) 93. [4] L. Skuja, J. Non-Cryst. Solids 39 (998) 6. [5] N. Kuzuu, M. Murahara, Phys. Rev. B 47 (993) 383. [6] N. Kuzuu, H. Horikoshi, T. Nishimura, Y. Kokubo, J. Appl. Phys. 93 (3) 96. [7] Y. Kikuchi, H. Sudo, N. Kuzuu, J. Ceram. Soc. Jpn. 5 (997) 645. [8] Y. Kikuchi, H. Sudo, N. Kuzuu, J. Appl. Phys. 8 (997) 4. [9] N. Kuzuu, J.W. Foley, N. Kamisugi, J. Ceram. Soc. Jpn. 6 (998) 55. [] T. Nishimura, I. Serizawa, N. Kuzuu, J. Ceram. Soc. Jpn. 8 () 34. [] G. Hetheringhton, K.H. Jack, Phys. Chem. Glass 3 (96) 9. [] A. Agarwal, K.M. Davis, M. Tomozawa, J. Non-Cryst. Solids 85 (995) 9. [3] K.M. Davis, M. Tomozawa, J. Non-Cryst. Solids (996) 77. [4] F.L. Galeener, J. Non-Cryst. Solids 7 (985) 373.

9 N. Kuzuu et al. / Journal of Non-Crystalline Solids 333 (4) [5] R. Tohmon, H. Mizuno, Y. Ohki, K. Sasegawa, K. Nagasawa, Y. Hama, Phy. Rev. B 39 (989) 337. [6] H. Imai, K. Arai, H. Imagawa, H. Hosono, Y. Abe, Phys. Rev. B 38 (988) 77. [7] H. Hosono, Y. Abe, H. Imai, K. Arai, Phys. Rev. B 44 (99) 43. [8] M. Tomozawa, Y.-L. Peng, A. Agarwal, Jpn. J. Appl. Phys. 37 (Suppl. ) (998). [9] A. Agarwal, M. Tomozawa, J. Non-Cryst. Solids 9 (997) 64. [] S. Sakaguchi, J. Non-Cryst. Solids (997) 78. [] J.C. Mikkelsen Jr., F.L. Galeener, J. Non-Cryst. Solids 37 (98) 7.