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Nucleation and growth behavior of tellurite-based glasses suitable for mid-infrared applications
Abstract
Optical fibers transmitting in the 2-5 mum mid-infrared (MIR) spectral region are highly desirable for a variety of military and civilian applications including supercontinuum generation, infrared countermeasures (IRCM), and MIR laser sources. These new applications in the mid-infrared require novel optical materials that transmit in this window and can be fabricated into fiber. As tellurite glasses are known to have good transparency in the (NIR) region, tellurite-based glasses are the material of choice for this study due to their high linear and nonlinear refractive index, their low glass transition temperature and the ability to form them into optical fiber. This dissertation summarizes findings on tellurite-based glasses with the composition (90-x)TeO2-10Bi2O3-xZnO with x = 15, 17.5, 20 and 25 that were processed and characterized for their potential application as novel optical fibers. Different techniques were deployed for characterization purposes, which include primarily linear refractive index measurements, structural characterization using Raman spectroscopy, and nucleation and growth behaviors, among others. The viscosity of the glasses was measured using a beam bending and parallel plate viscometers. The kinetics of crystallization of the bulk glasses and fiber with x =20 were studied using a differential scanning analyzer (DTA), a hot stage XRD and an optical microscope. The influence of compositional variation on the physical, thermal and optical properties of the glasses in the TeO2-Bi2O 3-ZnO family was established. The parameters such as the thermal properties, activation energy for crystallization, Johnson-Mehl-Avrami exponent, or nucleation and growth domains and rates were determined and were found to depend on the glass composition. We correlated the composition-dependent variation of these parameters to the structure of the glasses via Raman spectroscopy. Key physical, thermal, structural and optical differences were observed and quantified between bulk glasses and their corresponding core and core-clad fibers. Also reported are the processing and characterization of modified tellurite-based glass in the TeO2-Bi2O3-ZnO glass family and efforts to reduce their absorption loss due to residual hydroxyl (OH) content. We discuss the impact of this OH reduction in the tellurite network on the physical, thermal and structural properties as well as nucleation and growth behavior of bulk glass and fiber.
... Particularly, tellurite glasses present promising features such as working lower temperature [4]. Excellence tellurite glass can be used for various applications such as lasers, optical fiber amplifiers, broadband amplification, fiber optics, nonlinear optical devices, and so on [6][7][8][9]. ...
... Tellurite glasses doped with erbium ions have been studied intensively worldwide. The properties of erbium doped tellurite glasses are low melting temperature, high refractive index, large bandwidth and high emission cross section at 1.5 µm wavelength [4,6,10,11]. ...
... Tellurite glass has a higher refractive index than the other (approximately 1.9 to 2.25 depending on the composition) [6]. The addition of Er 2 O 3 to tellurite glasses increase the refractive index [8]. ...
This paper presents the optical properties of erbium doped tellurite glasses with the composition of 55TeO2-2Bi2O3-35ZnO-5PbO-(3-x)Na2O-xEr2O3 where x = 0, 0.5, 1.0, 1.5, 2.0, 2.5, and 3.0 mol% . Refractive index of the glasses was measured using Brewster’s angle method and their optical absorption spectra were measured in spectral range 200 – 1100 nm recorded at room temperature. The results show that the glass refractive index increases with the increase of Er³⁺ ion content in the glass and the optical band gap energy decreases with the increase of erbium content in the glass.
... Tellurite glasses have drawn much attention in recent years and are considered as promising materials for a variety of optical devices such as optical switches, fibers and optical storage devices due to their high transmittance from the visible to mid-infrared (MIR) spectral regions, high refractive index (n > 2) and unique non-linear optical properties [1][2][3]. ...
... Low crystallization temperature, high relative crystallinity, and narrow distribution of crystal size make this composition a good choice for high strength glass ceramics. As an important infrared material, transparency in the IR region is always essential for tellurite glass ceramics [3,4,9,16]. Therefore, further work was focused on the optical and mechanical properties of this composition. ...
... Because the glasses were melted under identical conditions, and the distribution of crystals appears uniform throughout the bulk, one explanation of the increase in crystal fraction with increasing Bi content is that the Bi leads to the formation of crystal nuclei in the glass as it is being quenched from the melt. These quenched-in nuclei are extremely difficult to avoid in tellurite glasses, and have been shown to impact the crystallization tendency [3]. In this model, the increased Bi content would induce the formation at high temperatures, close to that of the melt, of Bi-rich crystal nuclei, which are subsequently grown during the thermal treatment. ...
Glass ceramic materials with composition 75TeO2–xBi2O3–(25-x)ZnO (x = 13, 12, 11) possessing transparency in the near- and mid-infrared (MIR) regions were studied in this paper. It was found that as the Bi2O3 content increased in the glass composition, the observed crystallization tendency is enhanced, and high crystal concentrations were obtained for the glasses with high Bi2O3 content while maintaining transparency in the MIR region. Crystal size in the glass ceramic was reduced by adjusting the heat treatment conditions; the smallest average size obtained in this study is 700 nm. Bi0.864Te0.136O1.568 was identified using X-ray Diffraction (XRD) and found to be the only crystal phase developed in the glass ceramics when the treatment temperature was fixed at 335 °C. The morphology of the crystals was studied using Scanning Electron Microscopy (SEM), and crystals were found to be polyhedral structures with uniform sizes and a narrow size distribution for a fixed heat treatment regime. Infrared absorption spectra of the resulting glass ceramics were studied. The glass ceramic retained transparency in the infrared region when the crystals inside were smaller than 1 μm, with an absorption coefficient less than 0.5/cm in the infrared region from 1.25 to 2.5 μm. The mechanical properties were also improved after crystallization; the Vickers Hardness value of the glass ceramic increased by 10% relative to the base glass.
... This model argues that the glass structure is mainly controlled by the mean coordination number (MCN). It is defined as the set of concentrations of the corresponding elements multiplied by their covalent coordination number [24], [25]. This is an effective parameter that determines network connectivity [28]: in the Se 60 Ge 40 glass is composed of the spiral chains GeSe 2 and Ge 2 Se 3 [29]. ...
... Vickers micro-hardness was reported for an average of eighteen times by Hengyi MH-3, Shanghai. Hydrostatic density was carried out by the Archimedean method[25]. ...
In the present research, the effect of Antimony and Arsenic components on structural and optical properties of Ge40Se60 glass has been deliberated. For this aim, Ge40-xSe60Asx and Ge40-xSe60Sbx (5≤x≤25) bulk glasses were ready by the conventional melt and quenching method in fused-silica ampoule. Analysis such as infrared transmittance, bandgap energy, glass transition temperature, density, hardness, and refractive index of the samples was determined. Results show that a fully amorphous state can create in Ge40-xSe60Asx and Ge40-xSe60Sbx (5≤x≤25) systems. With rising Antimony and Arsenic contents, the amount of hardness and glass transition temperature of the glassy samples were decreased. The Infrared transparency of the Antimony-substituted glasses was in direct relation to Sb content and reduced to about zero in the Se60Ge15Sb25 system. The addition of As to the glass composition up to 20 mole % has a negligible effect on IR transparency of the Se-Ge-As system. By adding Arsenic to glass composition, the Eg decreased and reached to about 1.6 eV in Se60Ge15As25. The Eg of glasses reduces to zero by enhancement of Sb content up to 25 mole%. With increasing Antimony and Arsenic contents, the refractive index of the glassy samples was increased. The higher refractive index of Ge-Se-Sb glasses can be associated with a higher ΔP value of Sb-substituted glasses. With increasing As content, the bond strength of Ge2Se3 decreases, and the intensity of GeSe2 and As(Se1/2)3 bonds increases. So, all GeSe2 bonds are moved to a lower wavelength.
... Selain itu kaca silika juga memiliki kekurangan dalam hal transmisi pada daerah infrared. Hal ini dikarenakan kaca silika memiliki nilai absorbansi yang besar pada panjang gelombang infrared sekitar 3µm (Massera, 2009). Kekurangan kaca silika dalam hal transmisi pada daerah infrared dapat diatasi dengan menggunakan kaca yang terbuat dari bahan fluoride. ...
... Fiber optik yang dijual secara komersil dipasaran umumnya terbuat dari bahan silika (Si 2 O). Namun, fiber optik berbahan silika hanya dapat mentransmisikan gelombang pada rentang cahaya tampak dan memiliki loss yang cukup besar (Massera, 2009). Agar dapat mentransmisikan pada rentang gelombang infrared, maka modifikasi bahan pembuat kaca dan komposisi dilakukan pada berbagai penelitian salah satunya pada penelitian ini. ...
Peneltian ini bertujuan menganalisis spektrum Fourier Transform Infra Red (FTIR) dan menentukan minimum loss dari kaca Tellurite-Bismuth-Zinc-Plumbum (TBZP) yang dipengaruhi oleh variasi (PbO). Kaca TBZP difabrikasi dengan teknik melt quenching dengan komposisi 55TeO2–2Bi2O3–[43-x]ZnO–xPbO (%mol) dengan x=2, 3, 4, 5. Hasil uji spektrum Fourier Transform Infra Red (FTIR) menunjukkan pita absorbsi terbesar berada pada panjang gelombang lebih dari 620nm. Absorbansi tersebut lebih diakibatkan oleh adanya transisi vibrasi pada daerah infrared. Minimum loss pada kaca TBZP diprediksikan secara teoritis melalui fitting data infrared edge dengan kurva Rayleigh scattering. Minimum loss kaca TBZP sebasar 2,94 dB/km hingga 2,35 dB/km pada λ=5534,2nm hingga 5821,2nm. Nilai minimum loss menurun seiring pertambahan konsentrasi ion Pb2+ dalam kaca TBZP. Sifat tersebut menjadikan kaca ini sebagai kandidat yang baik untuk aplikasi yang menggunakan gelombang infrared seperti fiber optik infrared. The aims of this research were to analyze the spectrum of Fourier Transform Infra Red (FTIR) and determine the minimum loss of Tellurite-Bismuth-Zinc-Plumbum (TBZP) based glass which affected by the variation of (PbO). The TBZP glass has been fabricated by melt quenching technique with composition 55TeO2–2Bi2O3–[43-x]ZnO–xPbO (mol%) with x=2, 3, 4, 5. Fourier Transform Infra Red (FTIR) spectra test results showed that the greatest absorption bands were at wavelengths over 620nm. Vibrational transition has the reason behind the absorbance in the infrared region. Minimum loss on glass TBZP theoretically was predicted by fitted data from the infrared edge and rayleigh scattering curve. The minimum loss of TBZP was of the range 2,94 dB/km to 2,35 dB/km at λ=5534,2nm to 5821,2nm. The minimum loss of TBZP glass decreases as the Pb2+ content in glass increases. This makes these glasses are good candidate for IR-application such as infrared optical fiber.
... Nucleation-like (I) and growth-like (U) curves were measured to compare the tendencies of crystals to form under identical thermal protocols. Such I-U curves, as discussed in [43,44], complement traditional DSC data that only measures T g and T p , as well as provides information on the relative rates for nucleation and growth of crystals as a function of temperature. However, the measurements do not give absolute values of crystallization rates, as the precise quantity of as-formed nuclei is non-zero and not accurately detectable. ...
The impact of base glass morphology and post heat-treatment protocol on the mechanical properties (Vickers hardness and Young’s modulus) of a multi-component glass-ceramic was examined. Two parent chalcogenide glasses with identical composition but varying morphology (homogeneous and phase separated) were evaluated for their mechanical properties following identical thermal processing to induce crystallization. The nucleation and growth rates of the starting materials were compared for the two glasses, and the resulting crystal phases and phase fractions formed through heat treatment were quantified and related to measured mechanical properties of the glass ceramics. The presence of a Pb-rich amorphous phase with a higher crystal formation tendency in the phase-separated parent glass significantly impacted the volume fraction of the crystal phases formed after heat-treatment. Pb-rich cubic crystal phases were found to be dominant in the resulting glass ceramic, yielding a minor enhancement of the material’s mechanical properties. This was found to be less than a more moderate enhancement of mechanical properties due to the formation of the dominant needle-like As2Se3 crystallites resulting from heat treatment of the homogeneous, commercially melted parent glass. The greater enhancement of both Vickers hardness and modulus in this glass ceramic attributable to the high-volume fraction of anisotropic As2Se3 crystallites in the post heat-treated commercial melt highlights the important role base glass morphology can play on post heat-treatment microstructure.
... It is important to note that, the reported micro-hardness values represent the average of eighteen tests. The hydrostatic density of prepared glasses for 5 times was also determined by the Archimedean method (Massera 2009). ...
In the present study, the structural and opto-mechanical properties of Ge–Sb–As–Se–S chalcogenide glasses have been investigated. For this purpose, different bulk glasses of Ge20Sb5As15Se60−xSx (0 ≤ x≤50) were prepared by conventional melt quenching technique in quartz ampoule and different characteristics of prepared glasses such as glass transition temperature, density, hardness, transmittance, optical band gap energy and refractive index were determined. The value of hardness and glass transition temperature of prepared glasses were found to increase with increasing the sulfur content as a result of formation of GeS4 tetrahedral units and increasing the network connectivity and average bonding energy. The optical energy gap (according to Tauc’s relation), transmittance and refractive index of prepared glasses are in direct relation with sulfur content. In this study, the highest value of transmittance (about 70%) and lowest value of refractive index (2–2.3) was achieved in Ge20Sb5As15Se40S20 and Ge20Sb5As15Se10S50 glasses, respectively.
... Due to their high transmittance from the visible to mid-infrared spectral regions, high refractive index, and non-linear optical properties such as second harmonic generation (SHG), tellurite glasses have received much attention in recent years and are considered promising materials for a variety of optical devices such as optical switches, optical fibers and storage devices [1][2][3]. A drawback to these materials is their lower mechanical stability when compared to other oxide glasses; one method to improve mechanical strength is through for formation of a glass ceramic by nucleating and growing a crystal phase in the base glass network. ...
Glass powder of composition 70TeO2-20WO3-10La2O3 (mol%) was sintered to high density within a hot-press using a sacrificial powder as a pressure-transmitting medium. The potassium chloride (KCl) sacrificial power was found to minimize sample friction and adhesion to the die during pressing, facilitated the extraction of the densified sample from the die and was easily removable due to its water solubility. This fabrication process maximizes pressure transference to the green-body and enables sintered parts with optical quality comparable to those obtained by the melt-quench technique.
La demande de matériaux transparents dans l’infrarouge et notamment dans la région de 2 à 5 μm est de plus en plus croissante. Plusieurs familles de verre transmettent dans l’infrarouge de manière plus ou moins étendue, cependant leur fabrication complexe, leur faible résistance mécanique ou chimique ou encore leurs éléments constitutifs limitent leur mise en forme et leurs applications. Les verres d’oxydes de métaux lourds à base d’oxyde de gallium (Ga2O3) constituent d’excellents candidats à condition qu’ils puissent être mis en forme. Les travaux exposés dans cette thèse portent sur l’étude des propriétés et de la structure locale de trois systèmes vitreux riches en oxyde de gallium : GaO3/2-GeO2-NaO1/2, GaO3/2-LaO3/2-KO1/2-NbO3/2 et GaO3/2-GeO2-BaO-KO1/2. Les propriétés mécaniques, une étude de dévitrification, et la fabrication de fibre optique au moyen de différentes techniques (préforme, poudre dans tube, barreau dans tube et à partir d’un creuset ouvert) ont été réalisées sur une composition du système vitreux GaO3/2-GeO2-BaO-KO1/2.
Penelitian ini betujuan untuk memfabrikasi kaca Tellurite Zinc Bismuth (TZB) denga teknik melt quenching dan mendeskripsikan mengenai kondisi fisika (warna dan transparansi) kaca TZB. Bahan kaca yang digunakan dalam penelitian ini yakni serbuk Tellurite Oxide (TeO2) dengan kemurnian 99,99%, serbuk Zinc Oxide (ZnO) dengan kemurnian 99,9%, dan serbuk Bismut Oxide (Bi2O3) dengan kemurnian 99,9%. Komposisi yang digunakan adalah (80-x)TeO2-20ZnO-xBi2O3 dengan x=8,12,16 (mol%). Tahapan penelitian meliputi penyiapan alat dan bahan, pembuatan sampel dan karakterisasi sampel. Bahan dilebur di dalam furnace CARBOLITETM pada suhu 900oC selama 1 jam kemudian dituang ke dalam mold (cetakan) berukuran (3,5x2,5x0,5) cm yang telah dipanaskan pada suhu 300oC dan didinginkan secara natural cooling. Kaca TZB hasil fabrikasi seperti tampak transparan. Semua sampel kaca yang terbentuk berwarna kuning kehijauan (lime). Perlu dilakukan analisis lebih lanjut berupa UV-VIS untuk menentukan secara pasti pengaruh konsentrasi Bi2O3 sifat optis kaca TZB yang telah difabrikasi.
This research aims to fabricate Tellurite Zinc Bismuth (TZB) glass with melt quenching technique and to describe the physical condition (color and transparency) of TZB glass. The glass materials used in this research are Tellurite Oxide (TeO2) powder with 99.99% purity, 99.9% powder of Zinc Oxide (ZnO), and Bismuth Oxide (Bi2O3) powder with 99.9% purity. The composition used is (80-x) TeO2-20ZnO-xBi2O3 with x = 8.12,16 (mol%). Research stages include preparation of tools and materials, sample preparation and sample characterization. The material is melted in a CARBOLITETM furnace at 900°C for 1 hour then poured into a mold (sized) size (3.5x2.5x0.5) cm which has been heated at a temperature of 300oC and cooled by natural cooling. TZB glass fabrication results as it looks transparent. All glass samples are formed in greenish yellow (lime). Further analysis of UV-VIS is necessary to determine the exact effect of Bi2O3 concentration of the fabricated optical properties of glass TZB.
This paper presents the refractive index measurement of tellurite glasses using Brewster angle method. We propose a simple experimental method for finding the refractive index of tellurite glasses material using the polarization of light reflected by a dielectric surface near the Brewster angle. The refractive index of tellurite glasses with the composition of [55 TeO 2 -2Bi 2 O 3 -35ZnO-5PbO-(3-x)Na 2 O-xEr 2 O 3 ] with x = 0, 0.5, 1, 1.5, 2, 2.5, and 3 % mol are 1.85 for the first sample, 1.87 for the second sample, 1.91 for the third sample, 2.01 for the fourth sample, 2.05 for the fifth sample, 1.83 for sixth sample, and 1.67 for the last sample. The refractive index of tellurite glasses is also compared with the calculation of Lorentz-Lorenz equation.
The high power laser development required the need of materials with nonlinear properties. Glass materials can be considered as ideal materials as they can be transparent and elaborated in very large dimension. Precipitation of non-centro symmetric crystalline particles in bulk glass leads to a material with bulk nonlinear properties. This glass-ceramic should be then easily integrated in such laser facilities. In this thesis, the results concerning the precipitation of the LiNO3 phase in the glassy-matrix 35 Li2O- 25 Nb2O5- 40 SiO2 are detailed. The crystallization mechanism of this phase is studied through thermal analysis, optical and electronic microscopy as well as in-situ analyses. These studies reveal glass-ceramics are obtained through a precipitation of the lithium niobate crystalline phase in spherulite shape. The nonlinear optical properties are investigated on this materials and an original, isotropic Second Harmonic Generation signal (SHG) is registered in the bulk glass-ceramic. A complete study using a multi-scale approach allows the correlation between the spherulite structure and the nonlinear optical properties. A mechanism at the origin of the SHG signal is proposed. This leads to a new approach for transparent inorganic materials development for isotropic SHG conversion.
An extended study of lithium niobium silicate glass crystallization with the molar composition 35Li2O–25Nb2O5–40SiO2 is presented. Depending on the heat treatments, both surface and/or bulk crystallizations of the LiNbO3 crystalline phase were observed. X-ray diffraction together with second harmonic generation (SHG) measurements have revealed a net preferred orientation of the ferroelectric crystallites at the surface which is quite different in the bulk. A striking and promising SHG response estimated to be five times larger than -quartz has been observed in the bulk.
Recent advances in the application of glassy materials in planar and fiber-based photonic structures have led to novel devices and components that go beyond the original thinking of the use of glass in the 1960s, when glass fibers were developed for low-loss, optical communication applications. Exploitation of the material's compositional flexibility, combined with the ability to tailor all aspects of its size, shape, and physical properties as well as its behavior when exposed to all forms of electromagnetic radiation, has led to numerous breakthroughs. Thus, for the purposes of this review, we have divided the discussion to highlight issues of material composition and form and how both impact device function, focusing on the advances made within the past decades.
Non-radiative losses due to OH fluorescence quenching of the Nd 3+ 4 F 3/2 state are quantified over a range of OH concentrations from 4 · 10 18 to 4 · 10 20 cm À3 and Nd doping levels from 0.4 to 9 · 10 20 cm À3 in two K 2 O–MgO–Al 2 O 3 –P 2 O 5 metaphosphate glasses having different K/Mg ratios ($1/1 and 2/1). The quenching rate varies linearly with the Nd and OH concentrations as predicted by Forster–Dexter theory. However, in contrast to theory, the OH quenching rate extrapolates to a non-zero value at low Nd 3+ doping levels. It is proposed that at low Nd 3+ concentrations the OH is correlated with Nd sites in the glass. The quenching strength of OH on a per ion basis is weak compared to common transition metal impurities (V, Fe, Co, Ni, Cu and Cr). Nevertheless , OH dominates the Nd quenching in phosphate glass because under most processing conditions OH is present at concentrations 10 2 –10 3 greater than transition metal ion impurities.
A crystal growth rate vs. temperature (U vs. T)-type of curve for a Li2O.2SiO2 glass was determined up to a temperature of 690 °C using a differential thermal analysis (DTA) method. As determined from this (U vs. T)-type of curve, the temperature corresponding to the onset of crystal growth was 570±3 °C which is in excellent agreement with the same value determined by the conventional method. The complete range of temperature where crystal growth can occur and the temperature (Tmax) where the crystal growth rate is a maximum for this glass could not be determined. It is concluded that for temperatures <Tmax, the DTA method can delineate only a small, initial portion of the (U vs. T)-type of curve, where the crystal growth rate is sufficiently low so that the glass does not totally crystallize after the required (for at least 5 min) isothermal heat treatment at these temperatures. For temperatures >Tmax, the curve cannot be determined by the DTA method if the temperature for isothermal heat treatment is approached by heating the glass from room temperature. For determining the curve for temperatures >Tmax, the desired temperature (>Tmax) for isothermal heat treatment of the glass is suggested to be approached from the melting temperature of the glass.
The grain growth kinetics of silica and calcia doped alumina at 1400oC and their grain boundary complexion is characterized. These data are compared to predictions of both diffusion controlled and nucleation limited interface controlled grain growth theory. It is deduced from the indicators that the mechanism for normal and abnormal grain growth in these aluminas is diffusion controlled.
The TeO
2
-rich part of the TeO
2
-Nb
2
O
5
system has been investigated by temperature programmed X-ray diffraction and differential scanning calorimetry. Three invariant equilibria have been observed: one eutectic reaction (8 mol% NbO
2.5
, T
E
=690±5°C, L
E
TeO
2
+Nb
2
Te
4
O
13
), one peritectic reaction (incongruent melting, at 766±5°C, of the Nb
2
Te
4
O
13
compound) and one congruent melting reaction (congruent melting, at 810±5°C, of the Nb
2
Te
3
O
11
compound). A large glass-forming domain has been evidenced (0 to 25 mol% NbO
2.5
). The thermal behaviour of these glasses has been followed. The glass transition, crystallization temperatures and the nature of crystalline phases formed have been determined.
Unconventional bismuthate glasses containing lithium oxide have been prepared by a conventional melt-quench technique. X-ray diffraction, scanning electron microscopy, and differential thermal analysis show that stable binary glasses of composition xLi2O-(100-x)Bi2O3 can be achieved for x=20–35 mol %. Systematic variation of the glass-transition temperature, density, and molar volume observed in these glasses indicates no significant structural change with composition. Differential thermal analysis and optical studies show that the strength of the glass network decreases with the increase of Li2O content in the glass matrix with a small deviation for the extra stable 30Li2O-70Bi2O3 glass composition. Studies of Raman spectra and molar volume ensure that all glasses are built up of [BiO6] octahedral units, while the influence of Li+ ions in the glass matrix is also confirmed from optical, Raman, and electrical studies. Wide transmitting window in the optical region having sharp cutoffs in both ultraviolet-visible and infrared regimes may make these glasses useful in spectral devices. High dielectric values in these glasses compared to glasses formed with conventional glass former can be attributed to the influence of the high polarizability of the unconventional network forming cations, Bi3+.
Glass formation has been investigated in the binary systems GaF3MF2 (M = Ca, Sr, Ba) and GaF3YF3 and in GaF3SrF2MFn (M = Mg, Zn, Ca, Y). Glass transition occurs between 320 and 400°C. Fluorogallate glasses are of potential interest as low phonon energy glasses for passive and active optical fibers.
Fundamentals of Optical Fiber Sensor Technology The field of optical fiber sensors continues to expand and develop, being increasingly influenced by new applications of the technologies that have been the topics of research for some years. In this way, the subject continues to mature and reach into new areas of engineering. This text in the series on Optical Fiber Sensor Technology provides a foundation for a better understanding of those developments in the basic science and its applications in fiber sensors, underpinning the subject today. This book builds upon the work in an earlier single volume which covered a broad area of the subject, but which now, in this, volume 1 of the series, focuses upon the fundamentals and essentials of the technology. Material which is included has been carefully reviewed and in most cases thoroughly revised and expanded to reflect the current state of the subject, and provide an essential background for the more applications-oriented content of the subsequent volumes of the series. This volume opens with a status paper on optical fiber sensor technology, by Kenneth Grattan and Tong Sun providing in it a flavor of the main topics in the field and giving an essential overview at the sort of systems which are discussed in more detail in the other chapters in the whole series. An extensive publication list of readily accessible papers reflecting these topics is included.
Infrared optical fibers with low-loss were prepared using As-S, As-Ge-Se and Ge-P-S glasses by preform-drawing and double-crucible-drawing methods. Appropriate glass compositions for drawing low-loss optical fibers were found to be limited to the narrow ranges in the glass-forming regions. Chalcogens purification by distillation and rapid cooling of glass melts during preform glass preparation were effective in reducing the transmission loss. The lowest loss obtained was 64 db/km at 2. 40 mu m for an As//4//0S//6//0 unclad optical fiber. Minimum losses for As-Ge-Se and Ge-P-S systems were 290 db/km at 3. 40 mu m and 500 db/km at 2. 40 mu m, respectively.
Fluoride glass optical fibers have been proposed as an ultra-low-loss transmission medium. Progress in the development of these fibers is reviewed. In the first part of the paper, the practical and theoretical limits of transmission loss in fluoride materials and fibers are analyzed. The second part covers dispersion in single mode fluoride fibers, together with systems-related attenuation, and hence the operating limits of possible future systems are explored.
Using synchrotron radiation, structure of TeO2-ZnO glasses with three different ZnO contents (15, 25 and 35 mol%) are investigated by x-ray diffraction, Te K and Zn K EXAFS. X-ray diffraction study suggests the weak Te-O bond at 0·289 nm seen in α.-TeO2 crystal does not exist in the glass structure. Tellurium K EXAFS based on the two shell fitting method indicate that interatomic distances between Te and O atoms in axial sites decreased from 0·208 to 0·199 nm with increasing of ZnO contents, while interatomic distances between Te and O atoms in equatorial sites are the same. Zinc K EXAFS based on the two shell fitting method indicate the existence of the second oxygen shell located at the distance of 0·222-0·228 nm from Zn atom.
The nucleation rate (I) versus temperature type of curves for a Na 2O·2CaO·3SiO 2 (NC 2S 3) glass doped with 0.1 wt% platinum, 0.5 wt% Ag 2O, and 2.0 wt% P 2O 5 were determined using a previously developed differential thermal analysis (DTA) technique. In this DTA technique, a constant amount of glass sample was nucleated at selected temperatures for a specific time, followed by a DTA scan at a fixed heating rate. The functional dependence of the maximum intensity of the exothermic DTA crystallization peak ((δT) p) or the inverse temperature at the DTA peak maximum (T -1p) on the nucleation temperature (T n) was used to determine the nucleation rate versus temperature type of curves. Calculations for qualitatively assessing the dependence of (δT) p on T n were performed using I and crystal growth rate (U) curves for a hypothetical system. Values of (δT) p calculated for different degrees of overlap between the I and U curves were compared with those measured experimentally. The (δT) p vs T n curves depended strongly on the overlap of I and U, whereas the T -1p vs T n curves were unaffected by the overlap.
X-ray Diffraction: A Practical Approach
There are many different optical materials which transmit into the infrared spectral region to a lesser or greater extent. In historical sequence, there were first the natural crystals such as rock salt, then the synthetically produced single crystals and the special glasses, then semiconductor materials such as germanium and silicon. The most recent ones are the hot-pressed, compacted materials that are still in a state of vigorous development. In choosing an optical material to use in a specific application, the engineer or physicist must of course select one which transmits in the appropriate wavelength region, but he should also consider its other optical, mechanical, thermal, and chemical properties, with respect to the application in mind. In order to make the best possible decision, the designer should be equipped with all available data on these several properties, for the many materials. This article cannot of course supply such a great wealth of information. Only a few of the materials that are most likely to be generally satisfactory are included, and special attention is given to the hot-pressed compacts because of their relative novelty.
The transformation range viscosity, activation energy for viscous flow and the dilatometric critical temperature of sodium trisilicate glasses are all decreased by addition of water, whereas the thermal expansion coefficient in the elastic region is not altered to a significant extent. Although these effects are similar to those observed in vitreous silica, they are considerably reduced in magnitude. Since sodium trisilicate glasses are already highly depolymerized by the presence of Na2O, the additional depolymerization due to small additions of water does not seem adequate to explain these results. It is suggested that water behaves similarly to the alkali oxides and that the results of this study may be due to an extreme case of the mixed-alkali effect.
By means of the neutron diffraction method the atomic arrangement of a zinc-tellurite glass with composition 80% TeO2 + 20 mol% ZnO has been studied. Analysis of the radial distribution functions (RDFexp and RDFmodel) shows the presence of some changes in the basic structural units at the glass transition. Approximately 35% of the Te atoms conserve the same coordination state as in the α-TeO2 crystal structure. The remaining Te atoms are of lower coordination. The Gaussian distribution of the OO distances of the first coordination sphere ( = 2.95 Å) indicates an increasing assymmetry of TeO4, TeO3+1, TeO3 and ZnO4+1+1 polyhedra. The observed variations of the TeTe, Tesecond O and Osecond O distances greater than 3.0 Å have an essential contribution to tellurite melt amorphization. An attempt is made to give a stereochemical representation of the glass structure on the basis of the obtained RDFexp.
The properties and structure of (45−x)Na2O–xBaO–5ZnO–50P2O5 (0≤x≤45 mol%) glasses were investigated. These properties include density, molar volume and glass transition temperature. The increase of density of glasses with increasing BaO content can be interpreted by differences of masses. The variation in the molar volume of these glasses is small. The glass transition temperature increases as the BaO is substituted for Na2O. This behavior indicates that the replacement of Na2O by BaO improves the strength of the cross-links between the phosphate chains of the glasses. The analysis of the infrared spectra of the studied glasses reveals that the increase of BaO content decreases the formation of end groups [(PO3)n]n−.
New infrared fibers, the TeX glass fibers, operating from 3 to 13 μm, have been developed. Tellurium halide based glasses have been optimized to produce low loss optical core-clad fibers in the 7–9.5 μm domain, and two drawing techniques are described. IR spectroscopy of organic species have been performed with core-clad fibers.
Glasses in the system TeO2-Bi2O3-ZnO were studied with respect to their linear refractive indices and optical absorption in the UV-vis range. The third order non-linear refractive indices were measured using degenerated four wave mixing (DFWM). The optical Kerr susceptibilities calculated hereof were in the range from 5.49 to 6.58 x 10(-13) esu and hence 34-41 times larger than that of fused SiO2. They are roughly proportional to values theoretically calculated by the theory of Lines. (c) 2006 Elsevier B.V. All rights reserved.
The structure of MOTeO2 (M = Mg, Sr, Ba and Zn) glasses was investigated by Raman spectroscopy. The glasses with low BaO have a continuous network constructed by sharing corners of TeO4 trigonal bipyramids and TeO3+1 polyhedra having one non-bridging oxygen (NBO) atom. In the glasses, TeO3 trigonal pyramids having NBO atoms are also formed in the continuous network. In 36BaO · 64TeO2 glass, isolated structural fragments, such as TeO32− and Te3O84− ions, coexist with the continuous network. The structure of MgOTeO2 glasses is different from that of the BaOTeO2 glasses. In glasses containing about 40 mol% MgO, a (Te3O84−)n unit, in which n is relatively small, is formed. The fraction of tellurium atoms forming TeO3 trigonal pyramids increases with MgO content. When MgO exceeds 40 mol%, isolated structural units, such as TeO32− and Te3O84− ions, will be formed in glasses. The SrOTeO2 and ZnOTeO2 glasses have the same structure as the BaOTeO2 and MgOTeO2 glasses, respectively.
Ultra low loss of 0.151dB/km, which is the lowest attenuation ever reported,
has been achieved. Its impact on transmission systems with amplifiers such as EDFA
and Raman is also examined.
ZnO:Al films were deposited by RF magnetron sputtering in triode configuration applying an external DC electric field to the substrates. Reflection high-energy electron diffraction measurements characterized the different films as consisting of randomly-oriented zinc blende crystallites or randomly and texture-oriented wurtzite crystallites, as well as of the amorphous phase. The non-resonant Raman spectra are strongly influenced by the presence of a built-in electric field at the grain boundaries and they do not depend on the symmetry of the microcrystallites. The Raman spectra taken at resonant excitation are more sensitive to the presence of the amorphous phase in the films.
Calcium borophosphate glasses have been prepared by quenching melted mixtures of Ca(PO3)2 and B2O3. Their physical and chemical properties, such as glass transition and crystallization temperatures, density, microhardness, solubility in water and UV edge absorption, are studied as a function of the molar fraction B/B+P. The interpretation of the results are based on the presence of BO4 units and B–O–P bridges in phosphate-rich glasses. The substitution of sodium for calcium, for a constant B/B+P ratio (x=0.2), induces mainly the decrease of the intensity of the crystallization peak, which tends to vanish. This unexpected behaviour results, most probably, from an increasing disorder in the structure.
The hydroxyl (OH) content of calcium metaphosphate glasses has been controlled in the range 50–800 ppm by melting calcium
dihydrogen phosphate in air, under vacuum and with fluoride addition. Density, refractive index and glass transition temperature
of the glasses increase with decrease in OH content while the coefficient of thermal expansion remains almost unchanged. With
gradual decrease in OH, the UV cutoff initially shifts towards shorter and finally towards longer wavelengths. IR spectroscopic
study shows that the OH groups exist exclusively in the hydrogen bonded states. Correlations of the glass properties with
OH content have been explained in terms of structural rearrangement leading to the change in P-O bond length and O-P-O/P-O-P
bond angles of the PO4 tetrahedral units of (PO
3
−
)
n
chains. These changes are caused due to conversion of non-bridging oxygens (NBOs) of the H-bonded OH groups into bridging
oxygens (BOs) during progress of dehydroxylation.
Since the first announcement of low-loss fiber by Corning Glass Works in 1970, remarkable progress has been made in glass fibers for optical communication both in fabrication techniques and in fiber transmission characteristics. Various fabrication methods have been proposed and examined; the outside vapor-phase oxidation (OVPO) method, the modified chemical vapor deposition (MCVD) method, and the vapor-phase axial deposition (VAD) method, to name typical examples. These processes have enabled us to obtain graded-index multi-mode fibers with low loss and broad bandwidth, as well as low-loss single-mode fibers. In particular, the development of low transmission-loss fibers in the long-wavelength band opened up a new low-loss window in the wavelength bands of 1.3 µm and 1.55 µm.
This review paper describes recent progress in the fabrication methods and transmission characteristics of optical fibers, together with future trends and items for research in the field of optical communications.
A general new 4(n+1)×4(n+1) matrix formulation of Maker fringes applicable to any anisotropic material containing n layers, convenient and straightforward for experimental data analyses, is proposed. The treatment of the transmitted and reflected harmonic waves includes the contribution of anisotropic one-photon absorption for the fundamental and harmonic waves under the assumption of no pump depletion and leads to a complete analysis of any linearly or elliptically polarized harmonic signal recorded under various incident polarization configurations. In the framework of the proposed model, we report detailed results of Maker fringes in various samples, for instance, in one and two z-cut quartz plates separated by a controlled air gap.
The effects of F- ions in a germanium-lead-tellurite glass system on the spectral and potential laser properties of the Yb3+ are investigated. The absorption spectra, lifetimes, the emission cross-sections and the minimum pump intensities of the glass system with and without F- ions have been measured and calculated. The results show that the fluorescence lifetime and the minimum pump intensity of Yb3+ ions increase evidently, which indicates that germanium-lead-oxyfluoride tellurite glass is a promising laser host matrix for high power generation. FT-IR spectra were used to analyse the effect of F- ions on OH- groups in this glass system. Analysis demonstrates that addition of fluoride removes the OH- groups and results in improvement of fluorescence lifetime of Yb3+.
The properties of novel ternary tellurite glasses, based on the TeO2–BaO–Bi2O3 system, are reported for their applications in on-line chemical sensing and process control by characterizing the fundamental frequencies of molecular vibrations in the 2–5μm spectral region of mid-IR. The chemical sensing for process control also requires above room temperature operation (>100°C) for prolonged periods of time. Bulk samples of ternary tellurite glasses with a number of different compositions were prepared using heavy molecular weight oxides of TeO2, BaO, and Bi2O3. Infrared and Raman spectroscopic analysis was carried out together with differential thermal analysis to study the relationship between glass structure and thermal and viscosity properties. The temperature dependence of the viscosities of the glasses is also reported. The compositional dependence of Raman frequency shifts and the corresponding change in the coordination of Te–O structure is discussed. The results from the IR edge, reflection spectroscopic, and wavelength dependence of refractive index are also reported.
Properties and structures of potassium, barium and magnesium alumino-metaphosphate glasses (O/P≈3) have been investigated. Adding Al(PO3)3 to an alkali or alkaline earth metaphosphate glass improves the chemical durability, increases the glass transition temperature and reduces thermal expansion and residual OH-content. Infrared spectra are dominated by metaphosphate vibrational modes, the frequencies of which are dependent on the field strengths of the modifying cations. 27Al MAS NMR spectroscopy indicates that aluminum ions are incorporated into the aluminophosphate network primarily in octahedral sites, although tetrahedral and pentahedral sites are also present. The average aluminum co-ordination number decreases in the series K+>Ba2+>Mg2+ and this is related to a reduction in the basicity of glasses with higher field strength modifiers.
Polarized Raman spectra were obtained for a collection of borosilicate glasses that have been developed as candidate compositions for the immobilization of wastes generated from the reprocessing of Zircaloy-clad spent nuclear fuel. Raman spectra were obtained for borosilicate glasses with zirconia compositions as high as 21 wt%, as well as for crystalline ZrO2 (baddeleyite) and crystalline ZrSiO4 (zircon). As zirconia content in the glass is increased, two trends in the spectra indicate that the partially polymerized silicate tetrahedral network becomes more depolymerized: one, the polarized mid frequency envelope near 450 cm−1, assigned to Si–O–Si symmetrical bend modes, decreases in area; and two, the higher frequency band assigned to Si–O stretch in Q2 units (silicate chains) increases in area, while band areas decrease for modes assigned to Si–O stretch in more polymerized Q3 and Q4 units (silicate sheets and cages). These trends take place whether the glass composition is relatively simple or considerably more complex. As zirconia concentrations in the glass increase beyond 15 wt%, a series of sharp lines are observed in the spectra from baddeleyite crystals, and to a minor extent Zn–Cr spinel phases, superimposed on broad features from the glass matrix. A low intensity, broad band near 1400 cm−1 in the glass spectra is probably due to B–O stretch modes within BO3 units.
Two different approaches are currently used to study non-equilibrium crystallization. One is based on crystallization kinetic theories and the other is based on nucleation and crystal growth theories. The second, exact, treatment of the kinetics of crystallization under a non-isothermal regime is presented, based on models of nucleation and growth, to establish the temperature versus heating rate-transformation (THRT) and temperature versus cooling rate-transformation (TCRT) diagrams. The usefulness of the method is illustrated by analysis of the crystallization process in three model materials: an oxide glass (SiO2), a chalcogenide glass (Se61.5Ge15.4Sb23.1), and a metallic glass (Nd2Fe14B). The calculations also yield the justification and limitations both for the additivity assumption, often used to describe the relationship between isothermal and continuous heating/cooling crystallization studies, and for the empirical method of constructing the low temperature part of the time-temperature-transformation (TTT) and THRT diagrams, assuming an Arrhenius form of the crystallization rate constant. By using an exact method to construct the TCRT diagram, the crystallization temperatures predicted by the model are established. The critical cooling rate calculated is between two and four times lower than that obtained by use of the additivity assumption and between six and eight times lower than that resulting from the TTT diagram. By extension of the model, the THRT diagram is obtained and a critical heating rate is defined. In all cases, the exact heating rate is about two orders of magnitude higher than that obtained by use of the additivity assumption.
Three series of glasses based on Na2O3SiO2 glass, with substitutions of 15 and 25 mol% Al2O3 for SiO2, were prepared with varying water content by varying melting atmosphere and time. The viscosity and transformation temperature decrease with increasing water content. The effect of water content increases with increasing Al2O3 content. The results are explained in terms of the hydrogen bonding of the hydroxyl with the surrounding glass network.
The Vogel—Fulcher–Tammann–Hesse (VFTH) equation has been the most widespread tool for describing the temperature dependence with viscosity for strong, moderate and fragile glass-forming liquids. In this work, the VFTH equation was applied over a wide temperature range (between the glass transition temperature, Tg, and the melting point, Tm) for 38 oxide glasses, considering simple, binary and ternary compositions of silicate and borate systems. The Levenberg–Marquart non-linear fitting procedure was used to assess VFTH viscosity parameters B and T0, maintaining A=−5 fixed (in Pa·s) to reduce the number of adjustable parameters. Regarding this restriction, the VFTH formula has shown to adjust very well to experimental data in a wide temperature range. Previous assertions revealed that there is statistical correlation between B and T0. Principal component analysis (PCA) was used in the present study to verify the correlation between the B and T0 parameters [J. F. Mano, E. Pereira, J. Phys. Chem. A 108 (2004) 10824], as well as between Tg and Tm. In brief, PCA is a mathematical method aimed at reorganizing information from data sets. The results have shown that it is possible to map either borate (and almost fragile) or silicate (usually strong up to near fragile) systems. As a statistical tool, PCA justifies the use of B, T0 and Tg as the main parameters for the fragility indexes m=d(log10η)/d(Tg/T)|T=Tg and D=B/T0, where η is the viscosity and T the absolute temperature.
The association of chalcohalides and halogen leads to very stable glass compositions that allow the preparation of glass samples which are several centimeters thick. The potential interest of the glass is associated with its extended transmission in the infrared region for windows and fiber elaboration. It is, however, necessary to know the relative position of the nucleation and crystal growth rate curves to control both nucleation and crystal growth under heat treatments. Differential scanning calorimetry was used to determine the nucleation and crystal growth rate curves of a derived Ge-As-Se-I glass, and the curves showed the possibility of controlling the growth and preparing vitro-ceramics by eventually introducing a nucleating agent.
The effect of equimolar substitution of sodium borate for sodium metaphosphate on the glass-transition (T8) and crystallization (Tc) temperatures, molar volume (V), density (ρ), microhardness (Hv), water resistance (S) and ultraviolet edge absorption is studied in the compositional range NaPO3-Na2B4O7. An unexpected behavior is observed in the phosphate-rich domain implying the presence of BO4 units in the glass.
of a paper presented at Microscopy and Microanalysis 2007 in Ft. Lauderdale, Florida, USA, August 5 – August 9, 2007
Several properties of alkali–alkaline earth metaphosphate glasses have been measured. These properties include density, transformation range viscosity and dc electrical conductivity, with emphasis on the conductivity measurements. Glasses studied include series in which Li2O or Na2O is replaced by MgO, CaO or BaO, mixed alkali glasses containing a constant concentration of BaO and a series in which ZnO replaces BaO. The conductivity decreases by orders of magnitude as an alkaline earth oxide replaces either Na2O or Li2O. Replacement of one alkaline earth by another while maintaining the identity of the alkali ion has a much smaller effect on the conductivity of these glasses. The mixed alkali effect is evident in the conductivities of the Li–Na and Na–K glasses.
The role of the addition of niobium oxide in large amount on the Er3+ emission properties at 1535nm for excitation at 980nm in borophosphate glass has been investigated. An increase of the emission, associated with a decrease of the lifetime of the 4I13/2 erbium level and a larger absorption cross section of erbium and ytterbium at 980nm was evidenced. Changes induced on hydroxyl groups absorption with addition of Nb2O5 in glasses was clearly shown by IR Spectroscopy in the range 2500–3700cm−1. The relationship between erbium luminescence at 1535nm, Nb2O5 concentration and OH group nature in niobium borophosphate glasses has been discussed. A fluorination treatment, conducted to reduce the OH group content, has allowed the reduction of the absorption coefficient at 3000cm−1 by half. Amplification measured at 1535nm has confirmed the beneficial effect of the Nb2O5 introduction on the gain and has been found to be in accordance with the evolution of the luminescence properties.
New fluoride glasses have been obtained in the ZrF/sub 4/-ThF/sub 4/-BaF/sub 2/ systems. Large samples have been prepared in order to determine some physical properties. Optical transmission range lies from 0.22 to 7..mu.., the refractive index is about 1.53 and can be modulated by chemical composition. Glass temperature, crystallization and melting temperature have been measured.
Based on ab initio molecular-dynamics simulations, we have investigated the properties of TeO2 glass generated by fast quenching from the liquid phase. Structural properties of the glass model are in good agreement with available diffraction data. Inspection on the local structure of the glass phase reveals the presence of a great variety of Qmn polyhedra with the predominance of Q44 units typical of the crystalline phases of TeO2. Calculated IR and Raman spectra of amorphous TeO2 are in good agreement with experimental data and provide an assignment of the most prominent experimental peaks to specific phonons.
A glass formation region in the ZnO–TeO2–Bi2O3 system at 800 �C has been synthesized. The glass transition and crystallization
temperatures were studied by direct scanning calorimetry. The identification by X-ray powder diffraction of the phases appearing
during crystallization revealed cTeO2 form in TeO2–ZnO pseudo-binary for 18 mol% ZnO content which transforms into the stable
aTeO2 form at 500 �C. The compositions of the glasses, in the system treated at 450 �C reveal several phases. The value of refractive
index of the compositions of some glasses is about 2.2. Their densities were also obtained. The investigation in the system at 750 �C
by solid state reaction technique using XRD reveals two new phases: Bi4Te5Zn3O19 and Bi2TeZnO7. They crystallize with the monoclinic
and triclinic symmetry, respectively.
Infrared absorption spectra of GeO2-, P2O5-, and B2O3-doped fused silica
and nondoped fused silica have been obtained in the 3-25 micron
wavelength region. The loss spectrum is affected by dopants, especially
in the case of B2O3. The lower limit of attenuation in optical fiber is
estimated to be about 0.2 dB/km at 1.6 micron. Refractive-indices of
GeO2-and B2O3-doped fused silica were also measured precisely by a
minimum deviation method in the region of 0.4-2.4 micron.
Zero-material-dispersion wavelength shifts to longer wavelength with
increasing in GeO2 content, and is 1.30 micron with 7.5 mol% doping.
In the present research paper, a computer programme is generated to obtain a theoretical non isothermal Differential Scanning Calorimetric (DSC) curve with the help of some parameters obtained through experimental isothermal DSC curves. To demonstrate the validity of this process, a comparison between the experimental and theoretical non-isothermal DSC curves of chalcogenide glass Se70Te24Cd6 has been carried out. A function 'F' composed of some parameters, obtained from non isothermal experimental curves, is used to calculate the Avrami exponent. The computed Avrami exponent agrees well with the reported experimental value.