Sodium Tellurite Glasses Research Articles

Kinetic fragility of pure TeO2 glass

Pure TeO2 glass was prepared in a flash differential scanning calorimeter by applying fast quenching rates to a TeO2 melt. Matching cooling and heating rates of up to 30,000 K s−1 were then used to determine the respective fictive temperatures, corresponding to viscosity values as low as 105.3 Pa s. The interdependence between calorimetric data and viscosity was verified and fine-tuned for this compositional system utilizing sodium tellurite glasses. The fragility index of pure TeO2 (m = 64) is by far the highest reported for a single-component oxide melt.

Bismuth modified gamma radiation shielding properties of titanium vanadium sodium tellurite glasses as a potent transparent radiation-resistant glass applications

This work reported the radiation shielding characteristic of the bismuth titanium vanadium sodium tellurite glass system. The density of the specially-developed glass samples was increased from 2.21 to 4.01 g/cm3 with the addition of Bi2O3, despite the fact the molar volume is decease within 85.43–54.79 cm3/mol. The WinXcom program was used to approximate the effect of Bi2O3 on the gamma radiation shielding parameters of bismuth titanium vanadium sodium tellurite glasses. The μm values decrease with the increase of Bi2O3 concentration. The computed data shows that the glass sample with 20 mol.% of Bi2O3 content has the greatest radiation attenuation performance in comparison to other selected glasses. The Bi2O3–TiO2–V2O5–Na2O–TeO2 glass system shows excellent neutron shielding material with high long-term light transmittance and discharge resistance and could be potentially used as transparent radiation-resistant shielding glass applications.

Modification in Structural Properties of Erbium-doped Zinc – Sodium Tellurite Glass: Effect of Bimetallic Cu/Ti Nanoparticles

The effect of bimetallic nanoparticles (NPs) on the structural and optical properties of tellurite glass doped with Cu/Ti NPs are reported. A series of glass with composition of (70–x–y) TeO2–20ZnO–9Na2O–1Er2O3–(x)CuO–(y)TiO2 (where x = 0.0, 0.1 and 0.04 mol%, y = 0.0, 0.1 and 0.04 mol%) are synthesized by using melt-quenching method. The structure and optical properties of tellurite glass containing Cu/Ti NPs are identified by using X-ray diffraction (XRD), scanning electron microscopy-energy dispersive X-ray (SEM-EDX) technique and Fourier Transform Infrared Spectroscopy (FTIR). XRD spectra show the nature of glass and the grain size. The SEM images shows the surface morphology and EDX spectra show the traces of C, O, Te, Na, Zn, Au, Er, Ti and Cu elements. FTIR spectra show the chemical bonding of constituent atom in glass matrix primarily the Zn2+ vibration, Cu (II)–O bonding, Te–O bending in term of TeO3 and TeO4 units, Cu–H stretching and O–H vibration of water group.

Plasmon-enhanced luminescence of samarium doped sodium tellurite glasses embedded with gold nanoparticles: Judd-Ofelt parameter

A series of samarium doped sodium tellurite glass embedded with gold nanoparticles (Au NPs) in the composition (79-x)TeO2−20Na2O-1Sm2O3-xAuCl3 (x=0, 0.2, 0.4, 0.6, 0.8, 1mol%) are prepared using conventional melt quenching technique. The UV–Vis–NIR absorption spectra shows 9 bands corresponding to transition bands from ground state 6H5/2 to excited states 6P3/2, 4I11/2, 6F11/2, 6F9/2, 6F7/2, 6F5/2, 6F3/2, 6H15/2 and 6F1/2 in which the most intense bands are 6F9/2, 6F7/2, 6F5/2 and 6F3/2. The homogeneous distribution of spherical and non-spherical Au NPs (average size ~3.36±0.076nm) in the glassy matrix is evidenced from the transmission electron microscopy (TEM). The absorption spectrum of Sm3+ ions free glass sample containing Au NPs displays a two prominent surface plasmon resonance (SPR) band located at ~550nm and ~590nm. The infrared to visible frequency down conversion emission under 404nm excitation shows four emission bands centered at 577nm, 614nm, 658nm and 718 related to the transitions 4G5/2→6H5/2, 4G5/2→6H7/2, 4G5/2→6H9/2 and 4G5/2→6H11/2 respectively, corresponding to Sm3+ transitions. An enhancement in down conversion emission intensity of both green and red bands is observed in the presence of gold NPs either by increasing annealing time or by NPs concentration, the enhancement in photoluminescence (PL) intensity of glass containing 0.4mol% Au (as to be compared with glass without Au) shows the maximum enhancement by a factor of 1.90:1.82:1.97:2.25 times for all transitions band. The enhancement is mainly ascribed to the highly localized electric field of Au NPs positioned in the vicinity of Sm3+ ion. The enhancement of down conversion emission is understood in terms of the intensified local field effect due to gold NPs. The Judd-Ofelt parameters (Ωλ, λ= 2, 4, 6) are calculated that is used to estimate the important parameters such as total radiative transition probability (AT), stimulated emission cross-section (σpE), radiative lifetime (τR) and branching ratio (βR) for the excited levels of Sm3+ ions in the glass. Furthermore, the value of Ω2 for the studied glasses is found higher than that of glasses reported in the literature. These relatively higher values of Ω2 reflect low symmetry and high covalency around the Sm3+ ions. We assert that these tellurite glass nanocomposites can be used for developments of the solid-state lasers and nanophotonics applications.

Spectroscopic properties of Sm3+ doped sodium-tellurite glasses: Judd-Ofelt analysis

Modifying the optical response of rare earth doped inorganic glasses for diverse optical applications is the current challenge in materials science and technology. We report the enhancement of the visible emissions of the Sm3+ ions doped sodium-tellurite (TNS) glasses. The impacts of varying Sm3+ ions concentration on the spectroscopic properties of such glass samples are evaluated. Synthesized glass samples are characterized via emission and absorption measurements. The UV–Vis–NIR absorption spectra revealed nine absorption peaks which are assigned to the transitions from the ground level (6H5/2) to 6P3/2, 4I11/2, 6F11/2, 6F9/2, 6F7/2, 6F5/2, 6F3/2, 6H15/2 and 6F1/2 excited energy levels of Sm3+ ions. Emission spectra of the prepared glass under 404 nm excitation wavelength consisted of four bands centered at 561 nm, 598 nm, 643 nm and 704 nm which are originated from 4G5/2→6HJ (J = 5/2, 7/2, 9/2 and 11/2) transitions. The experimental oscillator strengths, fexp are calculated from the area under absorption bands. Using Judd-Ofelt theory and fit process of least square, the phenomenological intensity parameters Ωλ (λ = 2, 4, 6) are obtained. In order to evaluate potential applications of Sm3+ ions in telluride glasses, the spectroscopic parameters: radiative transition probability AR, branching ratio BR, radiative life time τr and stimulated emission cross section σλ for each band are calculated. These glass compositions could be a potential candidate for lasers.

Effect of Au NPs on the Spectral Modification of Er-Doped Zinc Sodium Tellurite Glass

Optimizing of the spectroscopic features of rare earth (RE) doped inorganic glasses via tuneable growth of metallic nanoparticles (NPs) is demanding in plasmonic based nanophotonics. We report the gold (Au) NPs assisted sizeable enhancements in Er3+ luminescence in zinc-sodium tellurite glass. Glasses of the form 70TeO2-20ZnO-10Na2O-(x)Er2O3-(y)Au (x = 0.0 and 1.0 mol%; y = 0.0-0.6 mol% in excess) are synthesized via melt-quenching method and thoroughly characterized. Au concentration dependent variations in the physical and spectroscopic properties of glasses are determined. XRD data confirms the amorphous nature of all samples. UV-Vis-NIR spectra reveal seven absorption bands corresponding to the transitions from ground state (4I15/2) to 4I13/2, 4I11/2, 4I9/2, 4F9/2, 2H11/2, 4F7/2 and 4F5/2 excited states of Er3+. TEM micrograph manifests the existence of non-spherical Au NPs with average size of 8.6 nm. Prominent surface plasmon band of Au NPs is evidenced around 629 nm. Furthermore, Au NPs display a SPR mediated strong absorption in the visible region. Room temperature visible down-conversion emission (under 425 nm excitation) reveal three significant peaks centred at 532 (moderate green represent 2H11/2 → 4I15/2 transition), 550 (weak green represent 4S3/2 → 4I15/2 transition) and 588 nm (strong green represent 4S3/2 → 4I15/2 transition). Glass containing 0.4 mol% of Au exhibiting the highest luminescence intensity is ascribed to the NPs local field enhancement and energy transfer between RE ions and NPs. Variations in the physical properties of glass are explained in terms of the alteration in structures and ligand interactions with Au NPs present in the glass network. The intense field amplification discerned in the vicinity of Au NPs is attributed to the charge accumulation at the surface of the NPs. Surface plasmon resonance (SPR) of Au NPs and energy transfer (ET) from NPs to Er3+ ions are primarily attributed for the observed spectral modification. It is established that our glass composition displaying such significant enhancement may be beneficial for the development of up-converted solid state lasers and other plasmonic devices.

Gold nanoparticles assisted structural and spectroscopic modification in Er3+-doped zinc sodium tellurite glass

Achieving enhanced spectroscopic properties of rare earth doped inorganic glasses by embedding metallic nanoparticles of controlled sizes is a challenging task. We report the gold (Au) NPs assisted modifications in structural and spectroscopic properties of melt-quench synthesized Er3+ doped zinc sodium tellurite glass. The growth of NPs is stimulated via time varying heat treatment at 300°C. XRD patterns confirm the amorphous nature of glasses and TEM images manifest the growth of gold NPs with sizes between 6.1 and 10.7nm. The heat treatment time dependent variations in physical properties are ascribed to the alteration in bonding of non-bridging oxygen ions. The UV–VIS–NIR spectra reveal six absorption peaks centered at 488, 523, 655, 800, 973 and 1533nm corresponding to the transition from ground state of 4I15/2 to 4F7/2, 2H11/2, 4F9/2, 4I9/2,4I11/2, and 4I13/2 excited states of Er3+ ions, respectively. Surface plasmon resonance (SPR) bands are observed in the range of 618–632nm. Judd–Ofelt analyses demonstrate a significant increase of spectroscopic quality factors (0.86–1.05) and branching ratio (0.62–92.38%). The up-conversion emission spectra of Er3+ exhibit three prominent peaks of reasonable green (502nm), a moderate green (546nm) and a strong red (629nm). An enhancement in the red band luminescence intensity by a factor of 8.19 and 8.54 times are achieved for 2 and 4h of heat treatments, respectively. This enhancement is attributed to the SPR effects of gold NPs producing an intense local field in the proximity of Er3+ ions and subsequent energy transfer between RE ions and NPs. The FTIR spectra display the presence of vibrational modes for ZnO4 bonds, Te–O bond in TeO3 (tp) and TeO4 (tbp) units and the hydroxyl groups. Excellent features of the results suggest that our method constitute a basis for tunable growth of gold NPs which is exceedingly useful for the optimization of optical and structural properties.

Alkali environments in tellurite glasses

Neutron diffraction measurements are reported for five binary alkali tellurite glasses, xM2O·(100−x)TeO2 (containing 10 and 20mol% K2O, 10 and 19mol% Na2O, and 20mol% 7Li2O), together with 23Na MAS NMR measurements for the sodium containing glasses. Differences between neutron correlation functions are used to extract information about the local environments of lithium and sodium. The Na–O bond length is 2.37(1) Å and the average Na–O coordination number, nNaO, decreases from 5.2(2) for x=10mol% Na2O to 4.6(1) for x=19mol% Na2O. The average Li–O coordination number, nLiO, is 3.9(1) for the glass with x=20mol% Li2O and the Li–O bond length is 2.078(2) Å. As x increases from 10 to 19mol% Na2O, the 23Na MAS NMR peak moves downfield, confirming an earlier report of a correlation of peak position with sodium coordination number. The close agreement of the maximum in the Te–O bond distribution for sodium and potassium tellurite glasses of the same composition, coupled with the extraction of reasonable alkali coordination numbers using isostoichiometric differences, gives strong evidence that the tellurium environment in alkali tellurites is independent of the size of the modifier cation used.

The TeO2‐Na2O System: Thermal Behavior, Structural Properties, and Phase Equilibria

Thermal behavior, structural properties, and phase equilibria of the (100−x)TeO2‐xNa2O system were studied in the 5 ≤ x ≤ 50 mol% composition range. Investigation of glass formation behavior in the binary system was realized, and the glass formation range was determined as 7.5 ≤ x ≤ 40 mol%. Differential thermal analysis (DTA) and Fourier transform infrared (FTIR) spectroscopy techniques were used for thermal and structural characterization of the glasses. Influence of Na2O content on glass transition temperature (Tg), glass stability (∆T), density (ρ), molar volume (VM), oxygen molar volume (VO), and oxygen packing density (OPD) values of sodium tellurite glasses was evaluated considering the structural transformations in the glass network. For the phase equilibria studies, DTA, X‐ray diffraction (XRD), and scanning electron microscopy/energy dispersive X‐ray (SEM/EDS) techniques were utilized to characterize the heat‐treated samples. According to the phase equilibria studies, three eutectic regions were detected in the 0 < x < 50 mol% composition range of the (100−x)TeO2‐xNa2O system. A new invariant endothermic reaction was detected for the compositions between 40 ≤ x ≤ 45 mol%. Na2O.8TeO2 (11.11 mol% Na2O) compound that was claimed to exist in the binary system in the literature was found to be the metastable δ‐TeO2 phase.

Gold nanoparticles assisted surface enhanced Raman scattering and luminescence of Er3+ doped zinc–sodium tellurite glass

Significant enhancements in Er3+ luminescence and Raman intensity mediated via surface plasmon resonance (SPR) of gold (Au) nanoparticles (NPs) embedded zinc–sodium tellurite glass are reported. The observed modifications in the physical and spectroscopic properties are ascribed to the alterations in the glass network. XRD pattern confirms the amorphous nature of prepared glass sample. UV–vis-NIR spectra reveal seven absorption bands. Surface plasmon band is evidenced around 626–630nm. TEM images manifest the growth of non-spherical Au NPs with average diameter between ~7.2nm and 8.6nm. The visible up-conversion (UC) emission for all samples under 779nm excitation exhibits three bands centered at 503nm (green), 546 (green) and 637nm (red) ascribed to 2H11/2→4I15/2, 4S3/2→4I15/2 and 4F9/2→4I15/2 transitions. Glass sample with 0.4mol% Au displaying the highest luminescence intensity with enhancement factor of 3.85 and 3.56 for green bands, and 7.61 for the red band is ascribed to the NPs local field enhancement and energy transfer between rare earth (RE) ions and NPs. FTIR spectra show the vibration of ZnO4 bonds, TeO bond in TeO3 (tp) and TeO4 (tbp) units and the hydroxyl groups. Raman spectra demonstrate the presence of ErO and ZnO bond, anti-symmetric vibrations of TeOTe bonds and stretching modes of non-bonded oxygen exists in TeO3 and TeO3+1 unit. The amplifications in Raman signals by a factor of 1.62, 1.58, 1.64, 1.68 and 1.69 corresponding to the peak centered at 262cm−1, 382cm−1, 521cm−1, 670cm−1 and 725cm−1 are attributed to the contribution of a surface plasmon generating a strong, localized and secondary field. We assert that our glass compositions offer favorable potential to develop solid state lasers and other versatile nanophotonic devices.

Enhanced upconversion emission of Dy3+-doped tellurite glass by heat-treated silver nanoparticles

Dy3+-doped lead sodium tellurite glasses containing silver nanoparticles (NPs) were synthesized by a melt-quenching technique and treated for different annealing time intervals above the glass transition temperature. The glass samples were characterized by UV–vis–IR absorption spectroscopy, photoluminescence spectroscopy and transmission electron microscope imaging. Eight absorption peaks of Dy3+ ions were observed indicating the transitions from ground state to different excited states. The surface plasmon resonance (SPR) peak of silver NPs was probed at 522nm. Blue, yellow and red luminescence emissions were recorded at 485, 578 and 665nm. The intensity of emission peaks for heat-treated samples containing silver NPs found to be 1.7–4 times larger than their singly-doped counterpart. Such enhancements are attributed to the modification of the local field due to difference between dielectric constants of metal and surrounding medium as the major factor, and energy transfer from nano-metal particles to Dy3+ ions as the minor aspect. The size distribution of silver NPs has a Gaussian shape with a maximum around 18nm. The glasses can be nominated as promising materials for solid state lasers.

Nano-silver enhanced luminescence of Eu3+-doped lead tellurite glass

Eu3+-doped lead sodium tellurite glasses containing silver nanoparticles (NPs) were synthesized by melt-quenching technique and annealed for different time intervals at above the glass transition temperature. The glasses were characterized by UV–Vis–IR absorption, photoluminescence spectroscopy and transmission electron microscope imaging. Four absorption peaks of Eu3+ ion were observed due to transitions from ground state to different excited states in 400–600nm region. The surface plasmon resonance (SPR) peak of silver NPs was probed at 632nm. Five emission lines were recorded at 568, 587, 614, 650 and 704nm which were intensified in the order of ∼1.9 times for heat-treated samples containing silver NPs. The average size of NPs was estimated to be ∼10nm. Different mechanisms for interaction of light with metal and luminescent ions are discussed. Such enhancements are attributed to the strong local electric field induced by SPR of silver NPs as the major factor, and energy transfer from surface of silver NP to Eu3+ ion. The glasses show promising properties for optical applications.

Luminescence Enhancement of Samarium-Doped Tellurite Glass Containing Silver Nanoparticles

Samarium-doped tellurite glass embedded with silver nanoparticles are synthesized by melt quenching technique and optically characterized. The effect of silver nanoparticles on the luminescent properties of the samarium-doped sodium tellurite glass is investigated. Upon pumping with 406 nm radiation, it is found that there are four distinctive emission bands centered at 562 nm, 599 nm, 645 nm and 705 nm. In the presence of silver nanoparticles in the glass substrates, we observe significant enhancement in the intensity of these emission bands. The enhancement tends to increase with the increasing of silver nanoparticles concentration. The mechanism of luminescence enhancement is discussed in terms of localized surface plasmon resonance.

Non-spherical gold nanoparticles mediated surface plasmon resonance in Er3+ doped zinc–sodium tellurite glasses: Role of heat treatment

Tuning the enhanced optical properties of rare earth (RE) doped inorganic glasses mediated via surface plasmon resonance (SPR) by embedding metallic nanoparticles (NPs) with controlled sizes is ever-demanding in photonics. Erbium (Er3+) doped zinc–sodium tellurite glasses containing gold NPs are prepared and spectroscopic characterization are made. The heat treatment temperature dependent variations in refractive index, density, molar volume, molar refraction and polarizability are ascribed to the alteration in bonding of non-bridging oxygen (NBO) ions originates from annealing processes between 325 and 400°C. X-ray diffraction pattern confirms the amorphous nature of the glass samples. TEM micrograph reveals the nucleation of heat treated Au0 NPs and SAED manifest their growth along the (111) crystallographic planes having average diameter in the range 7.4–10.3nm. The UV–vis spectra exhibit seven absorption bands corresponding to 4f–4f transitions of Er3+ ions. The SPR bands evidenced in the range 629–631nm validate the growth of gold NPs in the glass matrix. The glass annealed at 350°C displays maximum enhancement in the up-conversion (UC) emission intensity by a factor of 4.86 and 3.40 for green bands (2H11/2→4I15/2 and 4S3/2→4I15/2) and a strong enhancement by a factor of 4.91 for red band (4F9/2→4I15/2). The enhancement is primarily attributed to the local field effect of non-spherical NPs assisted SPR effects and the energy transfer processes between Er3+ ions and NPs. The excellent luminescence efficiency of proposed glasses nominates them potential for photonic devices and solid state lasers.

Judd–Ofelt analysis of spectroscopic properties of Sm3+ doped sodium tellurite glasses co-doped with Yb3+

A spectroscopic Judd–Ofelt investigation of co-doped sodium tellurite glasses is a key issue in lasers. Sm3+-doped glasses co-doped with various Yb3+ concentrations have been prepared by the melt quenching technique. These glasses have been characterized using XRD, optical absorption and luminescence techniques at room temperature. The amorphous nature of glasses has been confirmed by XRD spectra. The optical absorption spectra exhibited seven absorption peaks corresponding to the transition from ground level 6H5/2 to the various excited state of Sm3+ ions. The broad absorption band in the range of ~870–1040nm due to the large contribution of the absorption from 2F7/2→2F5/2 transition of Yb3+ ion was also observed. Judd–Ofelt theory have been applied to absorption intensities of Sm3+ transitions to determine the phenomenological intensity parameters, Ωλ (λ=2, 4 and 6). Emission spectra consisted of four emission bands 4G5/2→6H5/2, 6H7/2, 6H9/2 and 6H11/2. The J–O parameters have been employed to predict various radiative properties such as transition probability (AR), radiative lifetime (τf), branching ratio (βR), effective bandwidth (λeff), stimulated emission cross-section σ(λp), gain bandwidth and optical gain of trivalent samarium ion in 4G5/2 excitation level. The maximum values of stimulated emission cross section, gain bandwidth and optical gain were 23.09×10–22, 28.54×10–28cm3 and 12.51×10–25, respectively, corresponding to 4G5/2→6H9/2 transition in present glasses. The comparative studies with other Sm3+ doped different glasses showed that present glasses could be a potential candidate for lasers and broadband amplifiers.

Concentration dependent structural and spectroscopic properties of Sm3+/Yb3+ co-doped sodium tellurite glass

Tuning the optical and structural behaviors of tellurite glasses with controlled dopants is the key issue in solid state lasers and amplifiers. Sm3+/Yb3+ co-doped sodium tellurite glasses are prepared by the melt quenching technique and characterized using XRD, FTIR and DTA, optical absorption and luminescence techniques. The XRD spectra reveals the amorphous nature of glasses and the presence of functional groups such as Te–O bond in trigonal bipyramids (TeO4), Te–O bending vibration of the trigonal pyramids (TeO3) and non-hygroscopic nature of the glasses are confirmed from FTIR spectra. The DTA measurement shows the thermal stability lies in the range of 106–123. The UV–vis–NIR spectra exhibit eight absorption bands corresponding to the transition from ground level 6H5/2 to the various excited state of Sm3+ ions and the broad absorption band in the range of ~825–1100nm is ascribed to the large contribution of the absorption from 2F7/2→2F5/2 transition of Yb3+ ion. The experimental oscillator strengths calculated from the absorption spectra are used to evaluate three phenomenological Judd–Ofelt (J–O) intensity parameters Ωλ (λ=2, 4 and 6). Emission spectra consist of four bands 4G5/2→6H7/2 (moderate green) 4G5/2→6H5/2 (intense orange), 4G5/2→6H7/2 (moderate orange-yellow) and 4G5/2→6H11/2 (feeble red). The J–O parameters are employed to calculate radiative parameters such as transition probability (AR), branching ratio (BR), effective bandwidth (λeff) and stimulated emission cross-section σ(λp) of these emission transition of trivalent samarium ion. The optical band gap energy value (Eopt) and Urbach energy values (ΔE) are calculated and compared. The concentration dependent spectroscopic behavior of Sm3+-doped and Sm3+/Yb3+co-doped glasses is understood. Our systematic study may contribute towards the development of optical device fabrication.

Spectral investigation of Sm3+/Yb3+co-doped sodium tellurite glass

Sm 3+ /Yb 3+ co-doped tellurite glasses are prepared by melt-quenching technique. The density of the glasses varies between 4.65 and 4.84 g/cm 3 . The optical absorption spectra consist of eight bands in the wavelength range of 350-2 000 nm, which correspond to the transitions from ground level 6 H 5/2 to the various excited states of the Sm 3+ ion. Energy band gaps vary in the range of 2.73-2.91 eV, and the Urbach energy ranges from 0.21 to 0.27. Emission spectra exhibit four peaks originating from the 4 G 5/2 energy level centered at 576, 613, 657, and 718 nm. Quenches in emission bands may be due to the energy transfer from the Sm 3+ to Yb 3+ ions.

Enhanced 2.7 μm emission and energy transfer mechanism of Nd3+/Er3+ co-doped sodium tellurite glasses

2.7 μm emission properties and energy transfer mechanism of Nd3+/Er3+ co-doped sodium tellurite glasses are investigated in present paper. Absorption and emission spectra were tested to characterize the 2.7 μm emission properties of Nd3+/Er3+ co-doped sodium tellurite glasses and a reasonable energy transfer mechanism of 2.7 μm emission between Er3+ and Nd3+ ions was proposed. Intense 2.7 μm emission was obtained from Nd3+/Er3+ co-doped sodium tellurite glasses due to the efficient energy transfer from Nd3+ to Er3+ ions under 808 nm LD pumping. Meanwhile, strongly decreased 545 nm up-conversion and 1.5 μm emissions were observed. Additionally, to obtain efficient 2.7 μm emission, the optimized concentration ratio of Nd3+ to Er3+ was found to be 0.5:1 in present glass system. Our results suggest that the present Nd3+/Er3+ co-doped sodium tellurite glass might have potential application in mid-infrared lasers.

Study of sodium tellurite glass using the thermally stimulated depolarization current technique (TSDC)

In order to have a better understanding of the role of the structure and the defects involved in the polarization processes in an 85TeO 2–15Na 2O mol% glass, we used the thermally stimulated depolarization currents (TSDC technique). The TSDC of the non-irradiated sample presented a strong negative peak of current at the temperature of 340 K, preceded by a relatively weak positive peak at about 300 K, after different d.c. voltages of 1200, 1500 and 2000 V were applied. No response was obtained with 1000 V, but the peak intensity increased considerably for voltages above 1200 V. After γ-irradiation of 25 and 50 KGy doses, a depolarization of the negative peak was observed in the sample submitted to25 KGy, whereas for the sample irradiated with 50 KGy, six TSDC peaks appeared at regular intervals of 5 KGy, in the temperature range of 100 and 300 K.

Effect of nano-scale crystal field on the broadening of Er^3+- emission in sodium tellurite glass ceramics

In this paper we report the effect of heat treatment of 10 mol% Na(2)O-89.5 mol% TeO(2) glass for studying the fluorescence and line broadening behavior of Er-ions in the glass-ceramic matrix. Controlled crystal growth measurements using the X-ray line broadening technique for samples heat treated in the temperature range of 583-693 K were carried out and compared with the photoluminescence studies. The influence of crystal growth on line broadening of (4)I(13/2) spectra and metastable lifetime of (4)I(13/2) level is compared for various heat treatment temperatures. The full-width-of- half maxima increase with increasing heat treatment temperature and then fall rapidly at high temperatures.