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PubMed2005

Molecular mobility and the glass transition in amorphous glucose, maltose, and maltotriose.

We have used measurements of the phosphorescence intensity decay of the triplet probe erythrosin B, dispersed in amorphous glucose, maltose, and maltotriose at probe:sugar mole ratios of approximately 1:10(4), to monitor the molecular mobility of the sugar matrix in the glass and melt around the glass-transition temperature (Tg). Intensity decays were well fit using a stretched-exponential decay model in which the Kohlrausch-Williams-Watts lifetime tau and the stretching exponent beta are the physically meaningful parameters. When normalized to the glass-transition temperature, the erythrosin lifetime decreased in the order glucose>maltose>maltotriose. Analysis of the lifetime provided an estimate of the collisional quenching constant for deexcitation of the triplet state (kTS0); kTS0 increased in the order glucose maltose>maltotriose, indicating that the lifetime heterogeneity increased in the order glucose<maltose<maltotriose. These data demonstrate that both the average rate of matrix molecular mobility and the width of the distribution of matrix mobility rates around the glass transition increase with an increase in the molecular size of the sugar in this homologous series.

Glass↗
PubMed2006

The glass transition temperatures of sugar mixtures.

We measured the glass transition temperatures of mono-, di-, and trisaccharide mixtures using differential scanning calorimeter (DSC) and analyzed these temperatures using the Gordon-Taylor equation. We found that the glass transition temperatures of monosaccharide-monosaccharide and disaccharide-disaccharide mixtures could be described by the conventional Gordon-Taylor equation. However, the glass transition temperatures of monosaccharide-disaccharide and monosaccharide-trisaccharide mixtures deviated from the conventional Gordon-Taylor equation and the amount of deviation in the monosaccharide-trisaccharide mixtures was larger than those in the monosaccharide-disaccharide mixtures. From these results, we conclude that the size and shape of the sugars play an important role in the glass transition temperature of the mixtures.

Disaccharides↗
PubMed2004

Glass-forming property of the system diethyl sulphoxide/water and its cryoprotective action on Escherichia coli survival.

In this work the thermal properties of diethyl sulphoxide (Et2SO), as well as its cryoprotective ability are studied and related to other well-known cryoprotectant substances, like dimethyl sulphoxide (Me2SO). We have investigated the thermal properties of Et2SO/water systems using Differential Scanning Calorimetry at a very low heating/cooling rate (2 degrees C/min). Liquid/solid or glassy/crystalline transitions have been observed only for the solutions with content of Et2SO ranging from 5 up to 40% w/w and/or greater than 85%. In the 45-75% w/w Et2SO range we have found a noticeable glass-forming tendency and a great stability of the amorphous state to the reheating. In samples with Et2SO content ranging from 80 to 85%, we observed a great stability of the glass forming by cooling, but a lesser stability to the subsequent reheating. The glass-forming tendency of these solutions is discussed in terms of existing competitive interactions between molecules of Et2SO, on the one hand, and Et2SO and water molecules, on the other hand. The results are well explainable on the basis of the model structure of water/Et2SO solutions, deduced by Raman and infrared studies [J. Mol. Struct. 665 (2003) 285-292]. The cryoprotective ability of Et2SO on Escherichia coli survival has been also investigated, and a comparison among Et2SO and other widely used cryoprotectants, like Me2SO and glycerol has been done. Survival of E. coli, determined after freezing-thawing process, was maximal at 45% w/w Et2SO (more than 85% viability). It should be noted that at the same concentration the survival is only about 35% in the presence of Me2SO and not more than 15% in the presence of glycerol. These features are well consisted with the glass-forming properties of Et2SO.

Calorimetry, Differential Scanning↗
PubMed2004

Flexural properties of denture base polymers reinforced with a glass cloth-urethane polymer composite.

OBJECTIVES: A newly designed light-cured reinforcement made from urethanemethacrylate oligomer and woven glass cloth has orthotropic anisotropy. This is produced for incorporation into the outermost position under the greatest tension in denture base resins. In this study, the flexural properties of self-, heat-, and light-curing reinforced resins were determined. METHODS: The silanized glass cloth was soaked in urethanemethacrylate oligomer containing camphorquinone and 2-(dimethylamino)ethylmethacrylate. It was sandwiched between two pieces of polyethylene film and pressed to form a reinforcement sheet 0.3 mm in thickness, which was light-cured and prepared using four different surface conditions: with or without the polyethylene film and with or without a bonding agent. The reinforcement sheet was fixed in a fluorocarbon resin mold 3 mm in thickness, which was filled with self-, heat-, or light-curing resin and cured. The cured laminated plate was cut for flexural testing (40 x 7 x 3 mm3). A three-point flexural test was carried out at a crosshead speed of 2 mm/min and a span length of 30 mm. In this study, the glass fiber content was measured at percentages by weight because it was not possible to determine accurately the volume of the various polymers. RESULTS: The baseline flexural strengths of the self-, heat-, and light-curing resins were 76.2, 68.6, and 55.6 MPa, respectively, and these values were increased to 271.7, 216.4, and 266.5 MPa by the reinforcement sheet. The baseline flexural moduli of self-, heat-, and light-curing resins were 2.0, 2.4, and 2.1 GPa, respectively. These values were increased to 7.2, 5.1, and 6.6 GPa by the reinforcement sheet. SEM photographs revealed good impregnation of the glass fiber within the polymer matrix. SIGNIFICANCE: The differences in the flexural strengths and flexural moduli of the control and reinforced specimens were significant (p < 0.01).

Composite Resins↗
PubMed2006

Modification of glass fibers to improve reinforcement: a plasma polymerization technique.

OBJECTIVES: This study evaluates the effect of plasma treated E-glass fiber to improve the mechanical properties of acrylic resin denture base material, polymethylmethacrlyate (PMMA). Plasma surface treatment of fibers is used as reinforcement in composite materials to modify the chemical and physical properties of their surfaces with tailored fiber-matrix bonding strength. METHODS: Three different types of monomer 2-hydroxyethyl methacrylate (HEMA), triethyleneglycoldimethylether (TEGDME) and ethylenediamine (EDA) were used in the plasma polymerization modification of glass fibers. A radiofrequency generator was used to sustain plasma in a glass vacuum chamber. Glass fibers were modified at the same glow-discharge power of 25 W and exposure time of 30 min for each monomer. Fibers were incorporated into the acrylic with 1% (w/w) loading except control group. Specimens were prepared using a standard mold of 3 cmx0.5 cmx0.8 cm in dimension with eight specimens in each group. Samples were subjected to a flexural strength test set up at a crosshead speed of 5mm/min. Scanning electron microscopy (SEM) was used to examine the microstructure and X-ray photoelectron spectroscopy (XPS) was used for chemical analysis of the surface. RESULTS: Data were analyzed by means of ANOVA and Duncan's tests. Test results revealed that fiber reinforcement had a significant effect on the flexural strength of the specimens (p<0.05). Among the fiber reinforced groups, plasma treatment with EDA monomer resulted in the most significant increase in flexural strength values (p<0.05). XPS results have shown an increasing number of nitrogenous compounds in EDA treated fibers. The chemical structure of the surface, especially with the increase in nitrogenous compounds could give an idea for the amine film deposition and SEM figures showed an increase in surface roughness. SIGNIFICANCE: The results showed that plasma treatment with EDA monomer was an effective alternative method of increasing the flexural strength of PMMA based denture base polymers through fiber reinforcement.

Analysis of Variance↗
PubMed2006

Properties and cyclic fatigue of glass infiltrated tape cast alumina cores produced using a water-based solvent.

OBJECTIVE: The purpose of this study was to investigate the properties of tape cast alumina composite produced using a water-based solvent and its possible clinical use as an all ceramic crown system in a fixed partial denture. Durability of the system will be measured by fatigue test to simulate the masticating conditions of the oral cavity. METHODS: The optimal weight ratio of water-based alumina tape was determined by tensile strength, shrinkage ratio and durability. The coefficient of thermal expansion, fracture toughness, biaxial flexural strength and flexural strength after fatigue test of a composite produced from alumina tape at optimal weight ratios were determined and compared to In-Ceram alumina core (control). RESULTS: The weight ratio of alumina/(alumina+binder+plasticizer) of 0.84 and binder/(binder+plasticizer) of 0.5 was observed to be the optimal composition for achieving excellent composite properties. Coefficient of thermal expansion of the sintered alumina tape was observed to be 7.3x10(-6)/degrees C, and this value was increased to 7.5x10(-6)/degrees C after infiltrating the sintered tape with glass. The fracture toughness and biaxial flexural strength of glass infiltrated alumina tape was observed to be 4.6 MPa m(1/2) and 498 MPa, respectively. After cyclic loading for 10(2)-10(6) cycles, no significant change in the biaxial flexural strength was observed between the glass infiltrated alumina core and the In-Ceram alumina core (p>0.05). SIGNIFICANCE: The observed properties provide evidence that the water-based tape cast alumina-glass composite is suitable for clinical use as an all ceramic crown system in a fixed partial denture.

Aluminum Oxide↗
PubMed2006

Preliminary study on chitosan modified glass ionomer restoratives.

OBJECTIVES: The aim of this study was to investigate the effect of chitosan (CH), a biocompatible polysaccharide, on the flexural strength of glass ionomer restoratives (GIR) and on the release of fluoride ions from GIR. METHODS: Commercial GIR (Vidrion, SS White) has been modified by adding chitosan (CH, Fluka). Samples containing 0.0044, 0.012, 0.025 and 0.045wt% CH were prepared, molded and weighed. For flexural strength, sets of 10 specimens 10mmx2mmx2mm of commercial and CH modified GIR were prepared. Differences were analyzed by the one-way analysis of variances (ANOVA) test, at significance level 0.05. The data were also analyzed by post hoc Tukey's HSD for unequal n (Spjotvoll/Stoline) test. Scanning electron microscopy analyses were performed on the composites cryo-fracture surfaces. For the fluoride release tests and medium pH determination, discs with 10mm diameter and 2mm height were prepared in a PTFE mold placed between two glass slides. Samples were weighed in order to normalize each material test group. At least 10 samples of each material were prepared. Approximately 5min after preparation the discs were transferred into individual glass flasks containing 50mL of distilled water. The concentration of released fluoride was determined as a function of time by means of a fluoride ion selective electrode Orion 94-09 SC connected to an Ionanalyser (Orion Research Inc., USA). The medium pH was monitored as a function of time at (25+/-1 degrees C), using a Digimed DM20 potentiometer (Digicrom Instrumentos, Brazil) equipped with a combined glass electrode. Ellipsometric measurements were performed to quantify the thickness of adsorbed polymer (poly(acrylic acid) or the mixture of poly(acrylic acid) with CH). RESULTS: The addition of 0.0044wt% of CH led to a significant increase in the flexural resistance. CH contents higher than 0.022wt% led to poor performance. For the same period of time the amount of fluoride ions released from CH modified GIR was much larger than that released from commercial GIR. CH catalyzed the fluoride release from GIR to the medium, especially from those with 0.0044wt% of CH. As a consequence, the medium pH increased from 5.0 to 6.3. A model based on the formation of a polymeric network around the inorganic particles was proposed to explain the experimental findings. The adsorption of CH and poly(acrylic acid) onto planar Si/SiO(2) substrates was quantified and supported the proposed model. SIGNIFICANCE: The results presented here showed that the flexural strength of a commercial GIR can be considerably improved by the addition of a tiny amount of CH. Moreover, in the presence of CH, the release of fluoride ions from GIR is catalyzed.

Acrylic Resins↗
PubMed2006

Sintered glass ceramic composites from vitrified municipal solid waste bottom ashes.

A glass ceramic composite was obtained by sinter-crystallisation of vitrified municipal solid waste bottom ashes with the addition of various percentages of alumina waste. The sintering was investigated by differential dilatometry and the crystallisation of the glass particles by differential thermal analysis. The crystalline phases produced by the thermal treatment were identified by X-ray diffraction analysis. The sintering process was found to be affected by the alumina addition and inhibited by the beginning of the crystal-phase precipitation. Scanning electron microscopy was performed on the fractured sintered samples to observe the effect of the sintering. Young's modulus and the mechanical strength of the sintered glass ceramic and composites were determined at different heating rates. The application of high heating rate and the addition of alumina powder improved the mechanical properties. Compared to the sintered glass ceramic without additives, the bending strength and the Young's modulus obtained at 20 degrees C/min, increased by about 20% and 30%, respectively.

Aluminum Oxide↗
PubMed2006

Exchange-mediated spin-lattice relaxation of Fe3+ ions in borate glasses.

Spin-lattice relaxation times (T1) of two borate glasses doped with different concentrations of Fe2O3 were measured using the Electron Spin-Echo (ESE) technique at X-band (9.630 GHz) in the temperature range 2-6K. In comparison with a previous investigation of Fe3+-doped silicate glasses, the relaxation rates were comparable and differed by no more than a factor of two. The data presented here extend those previously reported for borate glasses in the 10-250K range but measured using the amplitude-modulation technique. The T1 values were found to depend on temperature (T) as T(n) with n approximately 1 for the 1% and 0.1% Fe2O3-doped glass samples. These results are consistent with spin-lattice relaxation as effected by exchange interaction of a Fe3+ spin exchange-coupled to another Fe3+ spin in an amorphous material.

Algorithms↗
PubMed2004

Electrical stimulation of isolated retina with microwire glass electrodes.

The development of high-resolution retinal prostheses fabricated from silicon wafers presents an interesting problem: how to electrically bridge the space between the flat silicon wafer and the curved retinal surface. One potential "bridge" is a microwire glass electrode. In this paper we present our results in evaluating microwire glass electrodes. We stimulated isolated rabbit retina (n = 5) with a 0.0256 cm(2) microwire electrode. The current and pulse duration were varied from 498 to 1660 microA and 0.1 to 3 ms, respectively. We found that short pulses produced more spikes per coulomb and longer pulses produced more spikes per milliamp. The optimal pulse duration range of 0.7-1 ms was identified as a compromise between the advantages of short and long pulses. Stimulation of isolated rabbit retina with microwire glass results in consistent neuronal spike formation at safe charge density, 20.7 +/- 4.3 microC/cm(2). We also examined the response of retinas (n = 6) to stimulation with a smaller microwire electrode, 0.0002 cm(2). We found that less current was required (15 microA versus 756 microA) for a 1 ms pulse, but at the expense of greater charge density (75 microC/cm(2) versus 29.5 microC/cm(2)). Nonetheless, a 128-fold reduction in area resulted in only a 2.7-fold increase in charge density required for a 1 ms pulse duration. The results presented here indicate that microwire glass can be used as a neural stimulating electrode to bridge the gap between flat microelectronic stimulator chips and curved neuronal tissue.

Animals↗
PubMed2004

The effect of reinforcement with woven E-glass fibers on the impact strength of complete dentures fabricated with high-impact acrylic resin.

STATEMENT OF PROBLEM: The fracture of acrylic maxillary complete dentures occurs frequently during service through heavy occlusal force or accidental damage. PURPOSE: The purposes of this study were to measure the impact strength of maxillary complete dentures fabricated with high-impact acrylic resin and to evaluate the effect of woven E-glass fiber-reinforcement on the impact strength of the complete dentures. MATERIAL AND METHODS: Preimpregnated woven E-glass fibers (Stick Net) were used to reinforce 10 complete denture bases fabricated with a heat-polymerized high-impact acrylic resin (Lucitone 199). Ten unreinforced complete dentures served as a control group. All specimens were stored in water at 37 degrees C for 2 months before testing. The impact strengths (J) of the dentures were measured with a falling-weight impact test. The impact strengths of both groups were compared by a repeated measures analysis of variance (alpha=.05). The Weibull distribution was also applied to calculate the cumulative fracture probability as a function of impact strength. RESULTS: The mean impact strength of the control dentures was 90.0+/-38.1 J at crack initiation, and 95.9+/-37.7 J at complete fracture, whereas the impact strength of reinforced dentures was 201.7+/-77.9 J and 277.9+/-102.5 J, respectively. Statistical analysis showed that impact strength of the high-impact acrylic complete denture was significantly increased by the addition of woven E-glass fiber (P<.0001). CONCLUSION: The impact strengths of maxillary complete dentures fabricated with high-impact acrylic resin increased by a factor greater than 2 when reinforced with woven E-glass fiber.

Acrylic Resins↗
PubMed2004

Survival rates of resin-bonded, glass fiber-reinforced composite fixed partial dentures with a mean follow-up of 42 months: a pilot study.

STATEMENT OF PROBLEM: Although short-term clinical data exist for resin-bonded, glass fiber-reinforced composite fixed partial dentures (FPDs), long-term data are needed. PURPOSE: The survival rates of 29 resin-bonded, glass fiber-reinforced composite fixed partial dentures were evaluated in this clinical study for periods of up to 42 months. MATERIAL AND METHODS: FPDs were fabricated to replace 1 to 3 missing maxillary or mandibular teeth of 29 patients not able to be treated with conventional FPDs. Originally, there were 37 patients (the drop-out rate was 22%). The FPDs were retained with wings, inlays, complete coverage crowns, or combinations of these that were bonded to tooth structure. The FPD frameworks were made of continuous unidirectional E-glass fibers with a multiphase polymer matrix and light-polymerized particulate composite veneer. The patients were recalled for examinations, where a general dental examination was performed, 1 to 3 times per year for up to 63 months (minimum 24 months, mean 42 months). Partial or complete total debonding of the FPD or the framework fracture was considered a treatment failure. The data were analyzed with the Kaplan-Meier survival test (alpha=.05). RESULTS: Two resin frameworks fractured, and 3 frameworks were debonded. Kaplan-Meier survival probability at 63 months was 75%. Three of the failed FPDs were rebonded or repaired in situ, producing a functional survival rate of 93% after rebonding or repairing (mean survival time was 55 months). CONCLUSION: The results of this clinical study of 29 prostheses suggest that glass fiber-reinforced FPDs may be a possible alternative to cast metal resin-bonded FPDs. These restorations were successfully used as multiple-unit prostheses that employed a variety of abutment tooth preparation designs.

Composite Resins↗
PubMed2005

Study of EPR, optical properties and electrical conductivity of vanadyl doped Bi2O3.PbO.B2O3 glasses.

Heavy metal based oxide glasses having composition xBi(2)O(3).(0.30 - x)PbO.0.70B(2)O(3) have been prepared (0.00 < or = x < or = 0.15, mol%) containing 2.0mol% of V(2)O(5) by normal melt-quenching technique. Electron paramagnetic resonance (EPR), optical spectra and dc conductivity of these glasses have been studied. Spin Hamiltonian parameters (SHP) of VO(2+) ions, dipolar hyperfine parameter, P and Fermi contact interaction parameter, K, molecular orbital coefficients (alpha(2) and gamma(2)) and optical band gap have been calculated. It is observed that in these glasses, the tetragonal nature of V(4+)O(6) complex increases with Bi(2)O(3) content. Increase in Bi(2)O(3):PbO ratio results in the contraction of 3d(xy) orbit of the unpaired electron in the vanadium ion, and the SHP are dependent on the theoretical optical basicity, Lambda(th). In present glasses, the conductivity (activation energy) first decreases (increases) with increase in mol% of Bi(2)O(3) content upto x = 0.08 and then shows a maxima (minima) at x = 0.10 and then starts decreasing (increasing) upto x < or = 0.15 with mol% of Bi(2)O(3) content.

Borates↗
PubMed2005

Study of luminescence properties of novel Er3+ single-doped and Er3+/Yb3+ co-doped tellurite glasses.

The novel Er(3+) single-doped and Er(3+)/Yb(3+) co-doped tellurite glasses were prepared. The effect of Yb(2)O(3) concentration on absorption spectra, emission spectra and upconversion spectra of glasses were measured and investigated. The emission intensity, fluorescence full width at half maximum (FWHM) and upconversion luminescence of Er(3+) go up with the increasing concentration of Yb(3+) ions. The maximum FWHM of (4)I(13/2) --> (4)I(15/2) transition of Er(3+) is approximate 77 nm for 1.41 x 10(21)ions/cm(3) concentration of Yb(3+)-doped glass. The visible upconversion emissions at about 532, 546 and 659 nm, corresponding to the (2)H(11/2) --> (4)I(15/2), (4)S(3/2) --> (4)I(15/2) and (4)F(9/2) --> (4)I(15/2) transitions of Er(3+), respectively, were simultaneously observed under the excitation at 970 nm. Subsequently, the possible upconversion mechanisms and important role of Yb(3+) on the green and red emissions were discussed and compared. The results demonstrate that this kind of tellurite glass may be a potentially useful material for developing potential amplifiers and upconversion optical devices.

Erbium↗
PubMed2005

Investigation of thermal stability and spectroscopic properties in Er3+/Yb3+-codoped TeO2-Li2O-B2O3-GeO2 glasses.

The new Er3+/Yb3+ co-doped 70TeO2-5Li2O-(25-x)B2O3-xGeO2 (x = 0, 5, 10, 15 fand 20 mol.%) glasses were prepared. The thermal stability, absorption spectra, emission spectra and lifetime of the 4I(13/2) level of Er3+ ions were measured and studied. The FT-IR spectra were carried out in order to investigate the structure of local arrangements in glasses. It is found that the thermal stability, absorption cross-section of Yb3+, emission intensity and lifetime of the 4I(13/2) level of Er3+ increase with increasing GeO2 content in the glass composition, while the fluorescence width at half maximum (FWHM) at 1.5 um of Er3+ is about 70 nm. The obtained data suggest that this system glass can be used as a candidate host material for potential broadband optical amplifiers.

Erbium↗
PubMed2004

VO2+ ions in zinc lead borate glasses studied by EPR and optical absorption techniques.

Electron paramagnetic resonance (EPR) and optical absorption spectra of vanadyl ions in zinc lead borate (ZnO-PbO-B2O3) glass system have been studied. EPR spectra of all the glass samples exhibit resonance signals characteristic of VO2+ ions. The values of spin-Hamiltonian parameters indicate that the VO2+ ions in zinc lead borate glasses were present in octahedral sites with tetragonal compression and belong to C4V symmetry. The spin-Hamiltonian parameters g and A are found to be independent of V2O5 content and temperature but changing with ZnO content. The decrease in Deltag( parallel)/Deltag( perpendicular) value with increase in ZnO content indicates that the symmetry around VO2+ ions is more octahedral. The decrease in intensity of EPR signal above 10 mol% of V2O5 is attributed to a fall in the ratio of the number of V4+ ions (N4) to the number of V5+ ions (N5). The number of spins (N) participating in resonance was calculated as a function of temperature for VO2+ doped zinc lead borate glass sample and the activation energy was calculated. From the EPR data, the paramagnetic susceptibility was calculated at various temperatures and the Curie constant was evaluated from the 1/chi-T graph. The optical absorption spectra show single absorption band due to VO2+ ions in tetragonally distorted octahedral sites.

Absorption↗
PubMed2006

Upconversion and fluorescence spectral studies of Er3+/Yb3+-codoped Bi2Q3-GeO2-Ga2Q3-Na2O glasses.

The absorption spectra and upconversion fluorescence spectra of Er3+/Yb3+-codoped natrium-gallium-germanium-bismuth glasses are measured and investigated. The intense green (533 and 549 nm) and red (672 nm) emission bands were simultaneously observed at room temperature. The quadratic dependence of the green and red emission on excitation power indicates that the two-photon absorption processes occur. The influence of Ga2C3 on upconversion intensity is investigated. The intensity of green emissions increases slowly with increasing Ga2O3 content, while the intensity of red emission increases significantly. The possible upconversion mechanisms for these glasses have also been discussed. The maximum phonon energy of the glasses determined based on the infrared (IR) spectral analysis is as low as 740 cm-1. The studies indicate that Bi2O3-GeO2-Ga2O3-Na2O glasses may be potential materials for developing upconversion optical devices.

Bismuth↗
PubMed2006

Raman spectrum, quantum mechanical calculations and vibrational assignments of (95% alpha-TeO2/5% Sm2O3) glass.

Chozen system of tellurite glasses doped with rare earth oxides (95% alpha-TeO(2)+5% Sm2O3) was prepared by melt quenching. Consequently, the Raman spectrum (150-1250 cm(-1)) of the modified tellurite have been recorded. As a continuation to our normal coordinate analysis, force constants and quantum mechanical (QM) calculations for tbp TeO4(4-) (triagonal bipyramid, C(2v)) and TeO(3+1); Te2O7(6-) (bridged tetrahedral), we have carried out ab initio frequency calculations for tpy TeO3(2-) (triagonal pyramidal, C(3v) and C(s)) and tp TeO3(2-) (triagonal planar, D(3h)) ions. The quantum mechanical calculations at the levels of RHF, B3LYP and MP2 allow confident vibrational assignments and structural identification in the binary oxide glass (95% alpha-TeO2 +5% Sm2O3). The dominant three-dimensional network structures in the modified glass are triagonal pyramidal TeO3 with minor features of short range distorted tbp TeO4 and bridged tetrahedral unit of TeO(3+1), leading to a structure of infinite chain. Therefore, alpha-TeO2/Sm2O3 (95/5%) glass experience structural changes from TeO4 (tbp); Te2O7 (TeO(3+1))-->TeO3 (tpy).

Ceramics↗