PbO Bi2O3 Ga2O3 Research Articles

Electrical properties of PbO–Bi2O3–Ga2O3 glasses with addition of Ag2O and Sb2O3

Formation of Ag nanoparticles in the PbO–Bi2O3–Ga2O3 heavy metal oxide glasses modified by addition of Ag2O and Sb2O3 was monitored using electrical and optical measurements. Electrical measurements are suitable for this purpose as they are very sensitive to any changes in the arrangement of the material structure. The formed spherical silver nanoparticles were studied by a high-resolution transmission electron microscopy (HRTEM), their nature was confirmed by selected area electron diffraction analysis (SAED) and x-ray photoelectron spectroscopy (XPS). We demonstrated and documented that the samples containing Ag/Sb change during additional heating (in the investigated temperature range of 240–290 °C) – the electrical conductivity changes and also the relaxation time as established by electrical modulus measurements changes. The behaviour of the base glass without Ag/Sb addition remains practically unaffected by the same additional heating. TEM confirmed an increased number of spherical nanoparticles as a consequence of heat treatment. The indexes of the SAED pattern match the fcc-Ag crystalline phase, HRTEM identified the periodical arrangement in these particles to correspond to d-spacing of (111) planes in Ag and the elemental state of the present Ag in the heat-treated sample was confirmed also by XPS.

Structure and photoluminescence properties of PbO–Bi2O3–Ga2O3 glass-ceramics containing silver nanoparticles, free lead and bismuth ions

We report the synthesis, structural characterization, and optical properties of PbO–Bi2O3–Ga2O3 glass-ceramics (GCs) containing PbO and Bi2O3 crystallites, free lead (Pb2+) and bismuth (Bi3+) ions, and silver nanoparticles (Ag-NPs). The samples were prepared by applying the melt-quenching method followed by suitable heat-treatment of the samples. Transmission Electron Microscopy, X-ray diffraction, linear optical absorption, and photoluminescence (PL) were the techniques applied to characterize the samples. When the samples were excited at 330 nm a large PL intensity, due to the Pb2+ and Bi3+, is observed. Moreover, large PL intensity enhancement of about 1000% for the samples containing Ag-NPs is observed in comparison with the PL intensity from the samples without Ag-NPs. This is the first time that this behavior is reported for a GCs based on heavy-metal oxides. The potential of this class of materials for photonic applications is discussed.

PbO–Bi2O3–Ga2O3–BaO glass nanocomposites as promising materials for elastoopticity

A new type of elastooptic materials based on PbO–Bi2O3–Ga2O3–BaO glasses have been fabricated. The studies of piezooptical effect at 1150 nm He-Ne laser wavelength have shown that the elastoopticity is crucially dependent on the nanoparticle (NP) sizes. The optimal effect exists at NP concentration equal to about 25%. The principal role of the interfaces between the glass nanoparticles and photopolymer PVA matrices is found. The piezooptic effect has shown sensitivity to the temperature also. The obtained values of piezooptical coefficients are compared with other glasses.

Development of silicate and germanate glasses based on lead, bismuth and gallium oxides for midIR microstructured fibers and microoptical elements

Three component PbO–Bi2O3–Ga2O3 glasses are characterized by high midIR transmittance, with a large susceptibility to crystallization. In this paper we investigate the increase in the thermal stability of these glasses by the addition of oxides such as GeO2, SiO2, Tl2O, CdO, Nb2O5. The resulting multicomponent glasses are well suited for the fabrication of microstructured fibers and micro-optical elements. The increased thermal stability of the modified multi-component glasses resulted in the IR absorption cut-off shifting to shorter wavelengths.

Optical evaluation of multichannel radiative transitions originating from G45/2 level of Sm3+ in heavy-metal-gallate glasses

Conventional visible and novel infrared (IR) emissions of Sm3+ in heavy-metal-gallate glasses (Li2O–K2O–BaO–PbO–Bi2O3–Ga2O3, LKBPBG for short) with low phonon energy have been observed. Judd–Ofelt parameters Ω2 (3.00×10−20 cm2), Ω4 (5.19×10−20 cm2), and Ω6 (1.69×10−20 cm2) indicate a higher asymmetry and stronger covalent environment in the optical glasses. For the visible fluorescence bands peaked at 564, 601, 648, and 710 nm, the maximum stimulated emission cross-sections (σe) were derived to be 1.35×10−22, 9.21×10−22, 9.58×10−22, and 3.91×10−22 cm2, respectively, the values are larger than those in phosphate, oxyfluoroborate, tellurite, and calibo glasses obviously. The observed 1185 nm IR emission lies in the low-loss window of telecommunication system, and the maximum value of σe for this band was obtained to be 6.09×10−23 cm2. The characterization of multichannel radiative transitions of Sm3+ in LKBPBG glasses is beneficial in exposing its potential applications in visible and IR optoelectronic devices.

Photo-Induced Effect in Heavy Metal Oxide Glasses

Photo-induced phenomena in binary (PbO–Ga2O3) and ternary (PbO–Bi2O3–Ga2O3) heavy metal oxide glasses were investigated. A red shift up to ∼0.05 eV in the absorption edge of 75PbO–25Ga2O3 glass (mol%) was observed by illuminating the subbandgap light for 30 min. This shift was completely erased by the heat treatment near the glass transition temperature. Refractive index of the glass at 600 nm also increased ∼0.011 by the illumination. It is believed that the presence of lone-pair electrons associated with Pb-polyhedra is essential to realize a reversible photo-induced effect in these oxide glasses.

Populations and Emission Properties of the 5I6 and 5I7 Levels in Ho3+ Doped into PbO–Bi2O3–Ga2O3 Glasses

Emission properties of PbO–Bi2O3–Ga2O3 glasses doped with Ho3+ were investigated for fiber‐optic amplification at the 1.18 μm wavelength region. When the glasses were doped with Ho3+ ions only, there was a weak emission at 1.18 μm with a lifetime of ∼200 μs. However, when Yb3+ ions were codoped, the lifetime of the 1.18 μm emission increased to 630 μs together with a significant increase in intensity. A similar enhancement in the intensity and lifetimes was realized for the 2.05 μm emission. These effects are due to energy transfer from the Yb3+:2F5/2 to the Ho3+:5I6 level. Devitrification of the ternary PbO–Bi2O3–Ga2O3 glasses was efficiently suppressed by adding 10 mol% GeO2. Optimum Ho3+ concentration was ∼0.4 mol%, whereas Yb3+ ions can be added up to the solubility limit.

Spectroscopic Properties of Er3+/Yb3+-codoped PbO–Bi2O3–Ga2O3–GeO2 Glasses

We investigate the spectroscopic properties of the 1.5-microm emission from the (4)I(13/2)-->(4)I(15/2) transition of Er(3+) ions in PbO-Bi(2)O(3)-Ga(2)O(3)-GeO(2) glasses for applications in broadband fiber amplifiers. The measured emission peak locates at 1,532 nm with a full width at half-maximum of approximately 45 nm. The glasses exhibit a large stimulated emission cross-section of 0.89 x 10(-20) cm(2) and a large FWHM x sigma(e)(peak) product of 40.0. Infrared-to-green upconversion occurs simultaneously upon excitation of the 1.5-microm emission with a commercially available 980 nm laser diode. The green-upconversion intensity has a quadratic dependence on incident pump laser power, indicating a two-photon process. Energy transfer processes and nonradiative phonon-assisted decays could account for the population of the (2)H(11/2) of Er(3+). The results indicate the possibility towards the development of lead-bismuth-gallate-germanate based glasses as photonics devices.

Thermal lens study of PbO–Bi2O3–Ga2O3–BaO glasses doped with Yb3+

The aim of this paper is to present a study of the thermal lens technique in quantifying the thermo optical coefficients: ds/dT (optical path change with temperature), thermal diffusivity and conductivity of PbO–Bi2O3–Ga2O3–BaO glasses doped with Yb3+. The thermal lens results indicate that the heat generation, as a function of the incident wavelength, resembles the absorption band 2F7/2→2F5/2 of Yb3+. Thermal diffusivity of 2×10−3cm2/s and thermal conductivity of 4.5×10−3W/Kcm were obtained and are similar to other glasses already reported in previous literature. The results emphasize that the thermal lens technique can be a powerful tool to study the heat generation of new glassy systems.

Laser spectroscopy of Nd3+-doped PbO–Bi2O3–Ga2O3–BaO glasses

We present spectroscopic results of PbO–Bi2O3–Ga2O3–BaO glass doped with different concentration of Nd2O3. These glasses have high refractive index (∼2.4) and large spectral transmission window. Measurements of absorption, emission and fluorescence lifetime are presented. From the calculations of the Judd–Ofelt parameters the radiative lifetimes, branching ratios and quantum efficiency of 4F3/2 level are calculated. The highest emission intensity was measured for the sample doped with 0.5wt% of Nd2O3 with emission cross-section of 2.6×10−20cm2, at 1069nm, fluorescence lifetime of 110μs, quantum efficiency of 82% and effective linewidth of 34nm. The results point out this glass system as good candidate to be used in the development of photonic devices operating in the near infrared spectral range.

Spectroscopic properties of Yb3+ doped PbO–Bi2O3–Ga2O3 glasses for IR laser applications

Abstract PbO–Bi 2 O 3 –Ga 2 O 3 glasses doped with different concentrations of Yb 3+ are presented. The spectroscopic properties and laser parameters are calculated and a comparison between different results obtained when calculating the Yb 3+ emission cross-section with the reciprocity method and with the Fuchtbauer–Ladenburg formula is presented. The behavior of the near-infrared luminescence is described theoretically by a rate equation and compared with the experimental results. This host doped with Yb 3+ is a promising material for laser action at 1019 nm, with properties similar to other known glasses used as active laser media; the emission cross-section of 1.1 × 10 −20 cm 2 , the high absorption cross-section (of 2.0 × 10 −20 cm 2 ) and a minimum pump intensity of 2.4 kW/cm 2 are interesting properties for short pulse generation.

Energy Transfer and Population Inversion in Heavy Metal Oxide Glasses Doped with Tm3+ and Tb3+

Emission properties and energy transfer of PbO–Bi2O3–Ga2O3–GeO2 glasses codoped with Tm3+ and Tb3+ ions were investigated. The 1.48‐μm emission due to the Tm3+:3H4→3F4 transition can be used to amplify the S‐band (1460–1530‐nm) signal light. With Tb3+ addition, the lifetime and emission intensity of the Tm3+:3F4 level decreased sharply via the Tm3+:3F4→Tb3+:7F0,1,2 energy transfer. Population densities of the 3F4 and 3H4 levels in Tm3+ calculated from rate equations clearly verified that population inversion in Tm3+ ions became possible with as little as 0.1 mol% of Tb3+ addition.

Quantitative Identification of Phonon Modes Controlling the Multiphonon Relaxation in Heavy‐Metal Oxide Glasses

The phonon mode(s) controlling the multiphonon relaxation (MPR) in PbO–Bi2O3–Ga2O3 glass was analyzed, and the effect of GeO2 addition on the MPR process was investigated. MPR rates were obtained from the lifetimes of the Tm3+:3H4 level in glasses over the temperature range 20–280 K. In PbO–Bi2O3–Ga2O3 glass, phonons from the bending vibration between GaO4 tetrahedra (∼550 cm−1) controlled the MPR process. On the addition of GeO2, the phonon mode at ∼770 cm−1 due to the stretching vibration of GeO4 tetrahedra started to affect the MPR process. Phonon modes controlling the MPR process in PbO–Bi2O3–Ga2O3–GeO2 glass were both 550 cm−1 and 770 cm−1.

Luminescence of the Yb-doped PbO–Bi2O3–Ga2O3–BaO glasses

Abstract Luminescence and absorption at wavelengths 600–1000 nm from Yb3+ ions embedded in PbO–Bi2O3–Ga2O3–BaO glass hosts is reported at room and helium liquid temperatures. We have found that excited pulsed XeII laser light (λ=714 nm) gives substantial luminescence at 980 nm with efficiency up to 63.2%. Kinetics of luminescence gives a decay time about 1050 μs. Explanation of the obtained results is presented within the framework of the Judd–Ofelt method and inclusion of electron–phonon anharmonicity.

Measurements of the spectroscopic and energy transfer parameters for Er^3+-doped and Er^3+, Pr^3+-codoped PbO–Bi_2O_3–Ga_2O_3 glasses

Measurements of the absorption and emission spectra and the characteristics of the luminescent decay of the 4I11/2 and 4I13/2 energy levels of Er3+ are presented for Er3+ singly doped and Er3+,Pr3+-codoped PbO–Bi2O3–Ga2O3 (PBG) glasses. The absorption cross sections were determined after accurate measurement both of glass component concentrations by use of electron probe analysis and of glass density. The characteristics of the luminescent decays were determined after direct pumping of the 4I11/2 and 4I13/2 energy levels of singly doped Er3+ PBG glass with a tunable pulsed optical parametric oscillator for calculation of the macroscopic rate parameters (WETU) for energy transfer upconversion (ETU) for these energy levels. The values for WETU relevant to the 4I11/2 energy level were measured to be greater than the WETU values relevant to the 4I13/2 energy level within the range of Er3+ concentrations studied. The macroscopic rate parameter (WEr-Pr) for energy transfer to the Pr3+ deactivator ion from the 4I13/2 energy level was also determined for a range of Pr3+ concentrations and for two fixed Er3+ concentrations. From a measurement of the energy-level lifetimes it was established that the rate of energy transfer from the 4I13/2 energy level to Pr3+ is greater than the corresponding rate of energy transfer from the 4I11/2 level to both the Pr3+ ion and the OH impurity. The overall results suggest that, to maximize the population inversion on the 4I11/2→4I13/2∼3 µm transition, deactivation of the 4I13/2 level by way of small amounts of Pr3+ will be effective.

Neutron and X-ray diffraction studies of PbOGa2O3 and Bi2O3Ga2O3 glasses

Abstract The structure of 50PbO·50GaO1.5 and 80BiO1.5·20GaO1.5 glasses was investigated by neutron and X-ray diffraction. Most Ga3+ ions are four-coordinated in both glasses. PbO3 trigonal pyramids and PbO4 square pyramids are present in 50PbO·50GaO1.5 glass. The stronger glass-forming ability in PbOGaO1.5 is attributed to (PbO3, PbO4)n infinite spiral chains as in crystalline PbSiO3. Bi3+ ions form BiO5 and BiO6 units in 80BiO1.5·20GaO1.5 glass as in α-Bi2O3. This glass may be constructed by (BiO5, BiO6)n layers and GaO33− chains. It is assumed that in these glasses nearly all oxygen atoms bonded to Pb2+ or Bi3+ ions are three- or four-coordinated and most oxygen atoms bonded to Ga3+ ions are three-coordinated. It is found that the structure of the present ‘non-conventional’ glasses are contrary to Zachariasen's rules for glass formation.