Doped Lead Borate Glasses Research Articles

Ultrasonic waves, mechanical properties and radiation shielding competence of Er3+ doped lead borate glasses: experimental and theoretical investigations

Ultrasonic waves, mechanical properties and radiation shielding competence of Er3+ doped lead borate glasses: experimental and theoretical investigations

Physical, optical and structural characterizations of Dy3+-doped lead borate glasses

In the current studies optical, physical and structural properties of rare-earth doped borate glasses have been reported. Bulk samples were prepared by using melt quenching technique with nominal composition 70B2O3-(17-x)ZnO-10PbF2-3Na2O-xDyF3 and 60B2O3-(27-x)ZnO-10PbF2-3Na2O-xDyF3, where (x=0,1). XRD analysis was used to confirm the amorphous nature of prepared samples. Optical and structural properties of as prepared samples were studied using UV-Visible and FTIR absorption spectra. The undoped and doped glasses exhibit characteristic absorption bands due to the presence of rare earth ion. A decrease in the band gap has been observed with the addition of rare earth ion. Variations in density have been observed with the addition of rare earth ion.

Concentration Dependent Spectroscopic Properties of Terbium Ion Doped Lead-Borate Glasses and Vitroceramics

Terbium ions doped lead borate glasses and vitroceramics with the composition of xTb4O7·(100-x)[4PbO·B2O3] where x is from 0 to 25 mol % Tb4O7 were prepared by the use of a melt-quenching protocol. Their structural and spectroscopic properties were characterized by x-ray diffraction (XRD), Fourier transform infrared (FTIR), Raman and ultraviolet-visible spectroscopies. The XRD patterns reveal the amorphous nature of the samples with low Tb4O7 content up to x equal to 1 mol % Tb4O7. Above this concentration, the analysis of XRD measurements indicates the presence of new crystaline phases in the vitroceramic samples. The FTIR and Raman measurements indicate that the addition of the rare earth oxides in the host network is realized by the deformation of the Pb-O-Pb or O-Pb-O angles, the formation of varied borate units and a large number of non-bridging oxygen atoms. The compositional evolution is conducted at the formation of crystalline phases of the terbium and lead atoms. The terbium atoms have a pronounced affinity toward the borate units while the lead atoms are attracted toward the oxygen atoms. Structural investigations by ultraviolet-visible spectroscopy show the presence of larger bands due to the f-f electron transitions of the Tb3+ ions and 6 s2 → 6s 6p transitions of Pb2+ ions, respectively. The optical gap energy values are dependent upon the concentration of the dopant level.

The influence of Ba2+ and Sr2+ ions with the Dy3+ ions on the optical properties of lead borate glasses: experimental and Judd–Ofelt comparative study

Two glasses compositions (50B2O3–30PbO–20SrO–xDy) and (50B2O3–30PbO–20BaO–xDy) where x=0.0.5%, and 1.0% in wt.% ratio were prepared using melt quenching technique in order to investigate the effect of Ba2+ and Sr2+ ions in Dy3+ ions doped lead borate glass. The optical properties such as bandgap and the refractive index distribution were examined using UV–vis-NIR absorption spectroscopy. The FTIR absorption spectra of all prepared samples were similar except for the metallic bands in the fingerprint region. The obtained experimental data were compared with theoretical data calculated by Judd–Ofelt framework. The Judd–Ofelt parameters Ωλ (λ=2, 4 and 6) were calculated and the trend was Ω2<Ω4<Ω6 which is the common trend. The experimental oscillator strength (fexp), the calculated oscillator strength (fcal), the estimated refractive indexes (n) at each transition, the lifetime of radiative transitions (τ), the branching ratio (β), the absorption cross-section (σabs(λ)) and the emission cross-section (σemis(λ)) were also estimated and discussed. The optical gain coefficient (G(λ)) was calculated not only for the most intense emission transition but also other emission peaks. The obtained results indicated that the prepared samples are promising materials for laser emission and optical communication applications.

Comparative impact of Nd3+ ion doping concentration on near-infrared laser emission in lead borate glassy materials

Different concentrations (0.2–1.0 mol%) of Nd3+ doped lead borate glass (LB) systems were prepared by melt quenching technique and have been studied using XRD and optical studies. Based on the calculations of Judd-Ofelt (J-O) theory derived from the optical absorption spectra, three J-O parameters have been obtained. Various radiative parameters (such as radiative transition probability (Arad), branching ratio (βcal), absorption cross-sections (Σ), radiative lifetime (τR) and etc., have been predicted through J-O parameters. Luminescence spectra were measured for all the samples. It has been observed that luminesce intensity gradually increased up to 0.8 mol % of Nd3+ and further increase in concentrations causes that the luminescence spectral intensity falls. This is proposed due to the concentration quenching of neodymium ions in the LB glass system. LB glass system with 0.8 mol % is found to be most intensive one in emission at 1.06 μm related to 4F3/2→4I11/2 in near infrared (NIR) transition.

The Magnetic, Electrical and Optical Properties of Rare Earth Er3+ Doped Lead Borate Glass

Owing to the unique electronic structure of rare earth elements, we address in this paper the magnetic, electrical and optical properties of a prepared lead borate glass of composition (mol.%) 70PbO·30B2O3. The glass is doped with different ErCl3 contents. A vibrating-sample magnetometer was used to characterize the magnetic properties. Increasing the additive concentration led to an increase in the saturation magnetization without significant effects on the coercivity. Optical reflectance spectra of the doped glasses revealed the development of absorption bands as a result of Er3+ intra-configurational (f–f) transitions. The calculated allowed direct energy gap was found to increase monotonically with increasing dopant concentration. The results of the ac conductivity showed a decrease in the activation energy values with increasing frequency and an increase in the ac conductivity values with increasing temperature, which mimics the semiconducting behavior. The incorporation of the rare earth ion (Er3+) facilitated the electronic conduction due to the increase of the non-bridging oxygen units. Increasing the dopant concentration led also to the participation of the ionic conductions. However, further increase of ErCl3 (above 1 mol.%) caused a decrease in the conductivity. Samples with dopant content up to 1 mol.% ErCl3 are accompanied by a high dielectric constant value of about 40. It can be concluded that samples doped with 1 mol.% ErCl3 or less can be used as energy storage material in electronic devices, whereas glass samples with higher dopant content can be used for magnetic applications.

Gamma Ray and FTIR Studies in Zinc Doped Lead Borate Glasses for Radiation Shielding Application

Gamma ray shielding properties of borate glass samples containing oxides of lead and zinc are prepared by melt and quench technique and evaluated theoretically using XCOM computer software for gamma ray shielding properties. However, gamma ray shielding properties are discussed in terms of various calculated parameters such as half value layer, mean free path and mass attenuation coefficient. The calculated parameters are compared by the author with conventional shielding material concrete. FTIR studies are undertaken to investigate the various structural groups present in the prepared system. Furthermore, it was observed that the glass sample S1 posses minimum HVL value and maximum mass attenuation coefficient, It has been inferred that addition of lead improve the gamma ray shielding properties and simultaneously decrease the rigidity of the glass systems due to formation of non bridging oxygen. Gamma ray shielding properties of our glass systems have been compared with standard nuclear radiation shielding concrete.

On the role of the network modifier PbO in Sm3+-doped borate glasses

A series of Sm3+-doped lead borate glasses with a lead oxide (PbO) content varying from 20mol% to 80mol% and a samarium oxide (Sm2O3) content of 1mol% is investigated. In addition to the network changes in the glass structure, the lead doping has a significant influence on the fluorescence properties of Sm3+ and on the tuneable intrinsic fluorescence of Pb2+ itself. The Pb2+ excitation band shifts monotonously to lower energies; its intensity is significantly reduced for a PbO content of 50mol% and more. For a concentration of 30mol%, the Pb2+ emission overlaps with the intense 6H5/2 to 6P5/2 Sm3+ excitation band enabling for radiative and non-radiative energy transfers. Lifetime measurements of excited Sm3+ show in all cases non-single exponential decay and were fitted by the Inokuti–Hirayama model indicating non-radiative dipole–dipole interaction between neighbouring Sm3+ ions.

Energy transfer from Tb3 + to Eu3 + in lead borate glass

Luminescence properties of Tb3+–Eu3+ doubly doped lead borate glasses were investigated. Luminescence spectra were measured under different excitation wavelengths. Characteristic luminescence bands related to electronic transitions of trivalent terbium and europium ions were detected under direct excitation of Tb3+. The energy transfer from Tb3+ to Eu3+ in lead borate glass occurs through a nonradiative process with an efficiency up to 18%. The presence of energy transfer process was also confirmed by excitation spectra measurements.

Samarium fluorescence efficiency in high mass density borate glasses

Abstract A series of Sm 3+ -doped lead borate glasses with a lead oxide content varying from 20 mol% to 80 mol% is investigated. Raman spectroscopy was used to investigate the influence of the network modifier content on the glass structure, in particular, on the phonon spectrum of the different lead borate glasses. In addition to the significant changes in the glass structure, the lead doping also has a significant influence on the fluorescence properties of Sm 3+ co-doped glasses.

Conversion of Ce3+ to Ce4+ ions after gamma ray irradiation on CeO2–PbO–B2O3 glasses

Abstract The structural and optical parameters of gamma ray irradiated cerium doped lead borate glasses have been analyzed using FTIR, UV–visible absorption, transmittance and density measurement techniques. It has been observed that due to gamma ray exposure, the optical band gap decreases, density increases and molar volume decreases correspondingly. FTIR spectroscopy confirms the conversion of [BO 3 ] to [BO 4 ] and also shows the presence of [CeO 4 ] groups of cerium in glass samples. The transmittance of the glass samples decreases due to formation of hole centers.

Combined DFT, Deconvolution Analysis for Structural Investigation of Copper –doped Lead Borate Glasses

Samples from binary lead borate glass system doped with minor quantities of copper have been prepared by conventional melt-annealing technique. X-ray diffraction (XRD) has been used to prove the amorphous nature of prepared glasses. Structural and optical properties were investigated using FTIR and UV-vis. Spectroscopic investigations were ap- proved using density function theory (DFT) calculations. Deconvolution analysis technique (DAT) combined with DFT technique were employed to interpret both of the theoretical and experimental IR data of this glass system and their agreement. Experimental IR data reveal the presence of both triangular and tetrahedral borate groups besides the sharing of Pb-O units. Direct and indirect optical energy band gaps before and after doping with different percents of copper were calculated to evaluate the role of copper in the glassy matrix. Undoped glass sample is observed to exhibit strong UV absorption due to the combined contributions of absorption of both Pb 2+ ions and trace iron impurities. The presence of both Cu 2+ ions to- gether with the other copper valence state Cu + has been proved by the appearance of extra visible absorption bands.

Optical and FTIR studies of CuO-doped lead borate glasses and effect of gamma irradiation

CuO doped lead borate glasses of the composition PbO 70%–B2O3 30% with varying CuO contents were prepared. UV–visible and infrared spectroscopic studies were measured before and after successive gamma irradiation with two different doses namely 2 and 8Mrad. The experimental results indicate that the undoped sample reveals strong UV–near visible absorption while copper doped samples show additional broad visible band due to (Cu2+) ions.FT infrared absorption spectrum reveals vibrational bands due to triangular and tetrahedral borate groups together with the sharing of Pb–O vibrations.CuO-doped glasses have been found to show a shielding behavior towards the effects of progressive gamma irradiation causing the maintenance of the spectral curves. The changes in the UV–visible and infrared spectral data are discussed in relation to the states of copper ions and structural evolution caused by the change in glass composition including the CuO.

Glass composition and excitation wavelength dependence of the luminescence of Eu3+ doped lead borate glass

This work explores the relationship between the bandwidth of luminescence spectral features and their relative intensities, using glasses doped with europium, Eu3+, over a wide composition range. Glasses of composition (B2O3)70(PbO)29(0.5Eu2O3)1 and (B2O3)z(PbO)99.6-z(0.5Eu2O3)0.4, (z = 20, 30, 40, 60, 70), were prepared by the melting-quenching technique. Variable-wavelength measurements by the prism-coupling method enabled interpolation of refractive index at selected wavelengths. Diffuse reflectance spectra confirmed the incorporation of Eu3+ into the glass, and scanning electron microscopy displayed that this was in a homogeneous manner. Vibrational spectra showed a change in boron coordination from BO3 to BO4 units with increase of PbO content in the glass. Multi-wavelength excited luminescence spectra were recorded for the glasses at temperatures down to 10 K and qualitative interpretations of spectral differences with change of B2O3 content are given. The quantitative analysis of 5D0 luminescence intensity-bandwidth relations showed that although samples with higher boron content closely exhibit a simple proportional relationship with band intensity ratios, as expected from theory, the expression needs to be slightly modified for those with low boron content. The Judd-Ofelt intensity analysis of the 5D0 emission spectra under laser excitations at low temperature gives Ω2 values within the range from (3.9–6.5) × 10−20 cm2, and Ω4 in the range from (4.1–7.0) × 10−20 cm2, for different values of z. However, no clear monotonic relation was found between the parameter values and composition. The Judd-Ofelt parameters are compared with those from other systems doped with Eu3+ and are found to lie in the normal ranges for Eu3+-doped glasses. The comparison of parameter values derived from the 10 K spectra with those from room temperature spectra for our glasses, which are fairly constant for different compositions, shows that site selection occurs at low temperature.

Unusual luminescence behavior of Dy 3+-doped lead borate glass after heat treatment

Dysprosium-doped lead borate glasses before and after heat treatment have been studied. Lead tungstate PbWO 4 crystallites were identified in lead borate glasses after heat treatment. Luminescence was examined under different excitation wavelengths. Blue luminescence of PbWO 4 crystallites embedded in lead borate glass is observed upon 310 nm excitation. Luminescence spectra measured under excitation at 390 nm consists of two characteristic blue and yellow bands, which correspond to 4F 9/2– 6H 15/2 and 4F 9/2– 6H 13/2 transitions of Dy 3+. Blue band is enhanced and broadened in comparison to yellow 4F 9/2– 6H 13/2 transition, when Dy 3+ and PbWO 4 crystallites in lead borate glass after heat treatment are simultaneously excited by 360 nm line.

Laser spectroscopy of rare earth ions in lead borate glasses and transparent glass-ceramics

Rare earth doped lead borate glasses and transparent glass-ceramics have been studied using optical spectroscopy. Based on the absorption, emission and its decay and the Judd-Ofelt calculations, several radiative and laser parameters for Ln 3+ (Ln = Pr, Nd, Eu, Dy, Er, Tm) were evaluated. The large values of luminescence lifetime, quantum efficiency of excited state and room temperature peak stimulated emission cross-section suggest efficient laser transitions of Ln 3+ ions in lead borate glasses. The obtained results indicate that lead borate glasses and glass-ceramics containing Ln 3+ ions are promising host matrices for solid-state laser applications.

UV-Visible and Infrared Spectra of Gamma-Irradiated Transition Metals-Doped Lead Borate Glasses

The UV-visible spectra of undoped and nominally transition metals (Ti→Cu) doped lead borate glasses have been measured from 200 to 1000 nm before and after various doses of gamma-ray irradiation. In the undoped lead borate glass, strong charge transfer ultraviolet absorption bands are observed which are related mostly to trace iron impurities and the possible sharing of Pb2+ ions. In transition metal (TM) doped glasses, characteristic absorption bands are recorded due to each specific TM ion which may interfere with that due to iron impurities. Gamma (γ-ray) irradiation reveals significant changes depending on the TM ion and some of the ions show retardation effect as observed in the induced bands. The responses of the undoped and TM-doped glasses to γ-ray irradiation are related to the formation of induced colour centers associated with the intrinsic or extrinsic defects in the glasses. The rates of formation or growth behaviour of the various induced defects are believed to approach saturation with prolonged irradiation.

Influence of compositions on sealing temperature and properties of lead borate non-crystallizing sealing glasses

Lead borate sealing glasses, composed of 30–75PbO, 20–65B 2O 3, 0–10ZnO, 1–5Bi 2O 3 and 0–4GeO 2 in mole percent, were prepared by conventional melting-quenching method. Influence of PbO/B 2O 3 ratios and the content of oxide additives on sealing temperature, thermal expansion properties, thermal stabilities and mechanical properties of lead borate glass were investigated by IR, DSC, thermal expansion and mechanical measurement. Results indicate that the ratio of PbO/B 2O 3, both as the main glass formers, had crucial influence on network structure of lead borate glass. An appropriate proportion of PbO/B 2O 3, ZnO and GeO 2 are beneficial to lower sealing temperature and stabilize the glass against devitrification. When 1 mol% GeO 2 is introduced, the glass possesses the highest stability and lowest sealing temperature (400 °C), which is desirable for low-temperature sealing. Bi 2O 3 has little effects on the melting temperature and sealing temperature, while it helps to improve mechanical properties of lead borate glasses. Only the introduction of GeO 2 causes a little tendency for crystallization. The modified Johnson–Mehl–Avrami (JMA) equation was used to describe the crystallization kinetics of GeO 2 doped lead borate glasses. The precipitation of crystals before melting is a block for the decrease of sealing temperature. Furthermore the adjustability of the coefficient of thermal expansion caused by the additives would expand applications of lead borate glass.

Self-quenching of spontaneous emission in Sm3+ doped lead-borate glass

The lifetimes of Sm 3+ doped in a binary glass are studied as a function of the complex refractive index of the glass. The local field effect has been taken into account and a real cavity around the emitter is assumed. The results are analyzed in the framework of the quantum electrodynamical equation to obtain a parameter that is related to the radius of cavity around Sm 3+ . The knowledge of this parameter is crucial in tailoring the lifetimes and has been found to be 1.48 nm.

Fluorescence line narrowing spectral studies of Eu 3+-doped lead borate glass

A lead borate glass of molar composition 49.5H 3BO 3–49.5PbO–1.0Eu 2O 3 was prepared and studied by broadband and fluorescence line narrowing spectral techniques. Site-selective 5D 0 → 7F 0,1 emission spectra were obtained under resonant excitation at different wavelengths along the 7F 0 → 5D 0 transition. These studies have been used to investigate the site-to-site variations in the spectroscopic properties of Eu 3+ ions in the lead borate glass at 13 K. The energies of the Stark levels of the 7F 1 multiplets are obtained from the experimental fluorescence line narrowing spectra and crystal-field analysis has been carried out, assuming C 2v orthorhombic symmetry, for each of the excitation energies. The distribution environments and the local structures of Eu 3+ ions in lead borate glass are found to be almost similar to calcium diborate glass and lies intermediate between Eu 3+-doped sodium borosilicate and lithium fluoroborate glasses.