Bismuth silicate glass as host media for some selected rare-earth ions and effects of gamma irradiation

Ultraviolet, visible and infrared spectral measurements were used to investigate prepared undoped and rare-earth doped (2.5%) bismuth silicate glasses (80% Bi₂O₃–20%SiO₂) before and after being subjected to gamma irradiation (8?Mrad). The base bismuth silicate glass reveals strong extended UV–near visible absorption bands which are attributed to the presence of trace iron impurities in the raw materials together with absorption due to sharing of Bi³⁺ ions. The RE-doped samples show the same strong UV–near visible bands as the undoped glasses beside extra narrow characteristic bands mostly in the visible and near-infrared regions due to the respective studied rare-earth ions. The base undoped and all RE-doped samples except CeO₂ sample reveal quite resistance to the effect of gamma irradiation due to heavy atomic mass Bi³⁺ ions present in high content (80%) and the rare-earth ions are known to be weakly affected due to the known 5s, 5p shielding. The exceptional effect of CeO₂-doped sample is related to the ability of Ce³⁺ ions to change its oxidation state through photochemical reaction by irradiation or exchange with Fe³⁺ present as trace iron impurities. The FT infrared spectra of the prepared glasses reveal characteristic absorption bands which are related to the silicate groups together with the sharing of vibrational modes due to Bi–O groups. The IR spectra are slightly affected by gamma irradiation indicating the stability of the structural network groups consisting of SiO₄ and BiO₆ units.     

UV-visible and infrared absorption spectra of Bi2O3 in lithium phosphate glasses and effect of gamma irradiation

Ultraviolet and visible absorption spectra of prepared undoped lithium phosphate glass and samples of the same nominal composition with additional Bi₂O₃ contents were measured before and after being subjected to gamma doses of 3 and 6 Mrad. The base undoped lithium phosphate glass exhibits strong charge transfer ultraviolet absorption bands, which are related to unavoidable presence of trace iron impurities within the raw materials for the preparation of this glass. Bi₂O₃-containing glasses show the extension of UV absorption beside the resolution of visible bands at 400, 450, and 700 nm with the increase of Bi₂O₃ content due the sharing of absorption of Bi³⁺ ions. Gamma irradiation of the base glass reveals extended induced bands; the UV bands are related to the conversion of some Fe²⁺ to Fe³⁺ through photochemical reactions during the irradiation process. The visible induced bands are related to the formation of positive hole centers from the host phosphate glass. Glasses containing Bi₂O₃ are observed to show some shielding behavior, which is attributed to the presence of heavy weight and large atomic number of Bi³⁺ ions. Infrared absorption spectral measurements of the base lithium phosphate glass show characteristic vibrational modes which are related to specific phosphate groups. The addition of Bi₂O₃ in measurable percent produces additional vibrational bands due to the introduction of Bi–O groups such as BiO₃ and BiO₆.     

Gamma ray interactions with MoO3-doped lead phosphate glasses

The UV–Visible, Fourier transform infrared (FTIR) and Raman and electron spin resonance (ESR) spectra of undoped lead phosphate and MoO₃-doped glassy samples have been investigated. The UV–VIS absorption spectra were re-measured after successive gamma irradiation. Before irradiation, undoped sample exhibited strong ultraviolet absorption, which was attributed to co-absorption due to trace iron impurities (mainly Fe³⁺ ions) and lead Pb²⁺ ions. With the introduction of MoO₃ in progressive amounts, extra visible bands were recorded at about 400–440, 540, 750 and 870?nm. These bands are most likely correlated with the presence of Mo³⁺, Mo⁴⁺ and Mo⁵⁺ ions in the host glass. In the undoped specimen, gamma irradiation produced UV absorption bands that increased slightly with irradiation but no visible bands were recorded. Samples containing high MoO₃ content showed some resistance to irradiation with no bands in the visible region being observed. FTIR absorption spectra of the undoped and MoO₃-doped samples revealed the formation of metaphosphate and pyrophosphate structural units. Highly MoO₃-doped samples exhibited additional bands due to molybdate groups. Raman and ESR spectra were in agreement with UV–VIS and IR data, indicating the presence of molybdenum ions in lead phosphate glass, as Mo³⁺, Mo⁴⁺ and Mo⁶⁺ with different ratios. However, such glassy systems favor the trivalent species.     

Interactions of gamma rays with undoped and Mn-doped sodium phosphate glasses

Ultraviolet and visible spectroscopic measurements were used to investigate prepared undoped and Mn-doped sodium phosphate glasses before and after successive gamma irradiation. The effects of both glass composition and MnO₂ content on the generation of radiation-induced defects were investigated. Undoped sodium phosphate glass shows strong UV absorption, which is attributed to the presence of trace iron impurities present in the raw materials. Mn-doped glasses reveal an additional visible broad band centered at about 500 nm due to Mn³⁺, which has recently been related to the ⁵E_g →⁵T_2g transition. The radiation-induced bands are correlated with the generation of liberated electron–hole pairs during the process of gamma irradiation and the possibility of photochemical reactions especially with trace iron impurities and manganese ions. The intensity and the position of the induced bands are observed to depend on the type and composition of glass, concentration of the dopant and also on the irradiation dose. Manganese ions when present in relatively higher content have been found to show a shielding behavior towards the effects of progressive gamma irradiation causing a retardation of the growth of the induced defects. Infrared and Raman spectra of the undoped and Mn-doped glasses were measured to investigate the structural phosphate groups present and the effect of MnO₂ on the network structure. An ESR investigation was carried out to confirm the state of manganese ions in the prepared sodium phosphate glasses.     

UV–visible,infrared absorption spectra of undoped and TiO2-doped lead phosphate glasses and the effect of gamma irradiation

Undoped and TiO₂-doped lead phosphate glasses were prepared. Ultraviolet (UV)–visible and Fourier transform-infrared (IR) absorption spectra of the prepared samples were measured before and after being subjected to doses of 30 and 60 kGy of gamma irradiation. The parent undoped lead phosphate glass reveals charge transfer UV absorption bands which are attributed to the presence of unavoidable iron impurities contaminated within the raw materials used for the preparation of the glasses and the sharing of divalent lead (Pb²⁺) ions. Experimental spectral data indicate that the doped titanium ions are involved in such glasses in two valences, namely the trivalent and tetravalent states. The predominant trivalent titanium (Ti³⁺) ions are characterized by its purple color and exhibiting two visible absorption bands at about 500–550 and 700–720 nm. The lesser tetravalent titanium (Ti⁴⁺) ions belong to the d⁰ configuration and generally exhibit only an UV absorption band. Spectral data show that gamma irradiation causes noticeable changes in the undoped and TiO₂-doped samples in the UV range while the effects are limited in the visible range. The observed changes in the UV region are attributed to photochemical reactions while TiO₂-doped samples show retardation or shielding toward continuous gamma irradiation together with the sharing of heavy Pb²⁺ ions. IR absorption spectra reveal the vibrations of several phosphate groups including the metaphosphate chains as the main structural building units together with the possible Pb?O vibrations.     

UV-visible and infrared absorption spectra of gamma irradiated CuO-doped lithium phosphate, lead phosphate and zinc phosphate glasses: A comparative study

Undoped and CuO-doped lithium phosphate, lead phosphate and zinc phosphate glasses were prepared. UV-visible and infrared absorption spectra of the prepared samples were measured before and after successive gamma irradiation. Experimental optical spectra of the undoped samples reveal strong UV absorption bands, which are attributed to the presence of trace iron impurities in both the lithium and zinc phosphate glasses while the lead phosphate glass exhibits broad UV bands due to combined absorption of trace iron impurities and divalent lead ions. The CuO-doped glasses reveal an extra broad visible band due to Cu²⁺ ions in octahedral coordination. The effects of gamma irradiation have been analyzed for both the sharing of all constituent components including trace iron impurities. Infrared absorption spectra of the prepared samples were investigated by the KBr disk technique. The FTIR spectra reveal main characteristic absorption bands due to different phosphate groups. The IR spectra are observed to be slightly affected by the increase of CuO in the doping level (0.2-3%) indicating the stability of the main network units.     

Luminescence spectroscopy of the Bi single and dimer centers in Y3Al5O12:Bi single crystalline films

Luminescence of the Bi³⁺ single and dimer centers in UV and visible ranges is studied in YAG:Bi (0.13 and 0.27 at% of Bi, respectively) single crystalline films (SCFs), grown by liquid phase epitaxy from a Bi₂O₃ flux. The cathodoluminescence spectra, photoluminescence decays, and time-resolved spectra are measured under the excitation by accelerated electrons and synchrotron radiation with energies of 3.7 and 12 eV, respectively. The energy level structure of the Bi³⁺ single and dimer centers was determined. The UV luminescence of YAG:Bi SCF in the bands that peaked at 4.045 and 3.995 eV at 300 K is caused by radiative transitions of Bi³⁺ single and dimer centers, respectively. The excitation spectra of UV luminescence of Bi³⁺ single and dimer centers consist of two dominant bands, peaked at 4.7/4.315 and 5.7/6.15 eV, related to the ¹S₀→³P₁ (A band) and ¹S₀→ ¹P₁ (C-band) transitions of Bi³⁺ ions, respectively. The excitation bands that peaked at 7.0 and 7.09 eV are ascribed to excitons bound with the Bi³⁺ single and dimer centers, respectively. The visible luminescence of YAG:Bi SCF presents superposition of several wide emission bands peaking within the 3.125-2.57 eV range and is ascribed to different types of excitons localized around the Bi³⁺ single and dimer centers. Apart from the above mentioned A and C bands the excitation spectra of visible luminescence contain wide bands at 5.25, 5.93, and 6.85 eV ascribed to the O²⁻→Bi³⁺ and Bi³⁺→Bi⁴⁺ + e charge transfer transition (CTT) in Bi³⁺ single and dimer centers. The observed significant differences in the decay kinetics of visible luminescence under excitation in A and C bands of Bi³⁺ ions, CTT bands, and in the exciton and interband transitions confirm the radiative decay of different types of excitons localized around Bi³⁺ ions in the single and dimer centers.     

Near-infrared broadband luminescence in Bi<Subscript>2</Subscript>O<Subscript>3</Subscript>-GeO<Subscript>2</Subscript> binary glass system

Near-infrared broadband luminescence from 1100 to 1600 nm was observed in Bi₂O₃-GeO₂ binary glasses. The strongest emission can be observed with 30 mol % Bi₂O₃ when pumped at 808 nm. The lifetimes of all samples are longer than 200 μs. The glass network was studied by Raman spectra and Bi⁺ ions are proposed as the infrared luminescence centers in this glass system. Thermal treatment in air results in partly oxidation of Bi⁺ to Bi²⁺.     

Synthesis, characterization, thermo- and photoluminescence properties of Bi3+ co-doped Gd2O3:Eu3+ nanophosphors

Gd₂O₃:Eu³⁺ (4 mol%) co-doped with Bi³⁺ (Bi = 0, 1, 3, 5, 7, 9 and 11 mol%) ions were synthesized by a low-temperature solution combustion method. The powders were calcined at 800°C and were characterized by powder X-ray diffraction (PXRD), transmission electron microscopy (TEM), Fourier transform infrared and UV–Vis spectroscopy. The PXRD profiles confirm that the calcined products were in monoclinic with little cubic phases. The particle sizes were estimated using Scherrer’s method and Williamson–Hall plots and are found to be in the ranges 40–60 nm and 30–80 nm, respectively. The results are in good agreement with TEM results. The photoluminescence spectra of the synthesized phosphors excited with 230 nm show emission peaks at ～590, 612 and 625 nm, which are due to the transitions ⁵D₀→⁷F₀, ⁵D₀→⁷F₂ and ⁵D₀→⁷F₃ of Eu³⁺, respectively. It is observed that a significant quenching of Eu³⁺ emission was observed under 230 nm excitation when Bi³⁺ was co-doped. On the other hand, upon 350 nm excitation, the luminescent intensity of Eu³⁺ ions was enhanced by incorporation of Bi³⁺ (5 mol%) ions. The introduction of Bi³⁺ ions broadened the excitation band of Eu³⁺ of which a new strong band occurred ranging from 320 to 380 nm. This has been attributed to the 6s²→6s6p transition of Bi³⁺ ions, implying a very efficient energy transfer from Bi³⁺ ions to Eu³⁺ ions. The gamma radiation response of Gd₂O₃:Eu³⁺ exhibited a dosimetrically useful glow peak at 380°C. Using thermoluminescence glow peaks, the trap parameters have been evaluated and discussed. The observed emission characteristics and energy transfer indicate that Gd₂O₃:Eu³⁺, Bi³⁺ phosphors have promising applications in solid-state lighting.     

Assessment of role of iron ions on the physical and spectroscopic properties of multi-component Na2O−PbO−Bi2O3−SiO2 glass ceramics

Multi-component glass ceramics composition Na₂O?PbO?Bi₂O₃?SiO₂ doped with different concentrations of Fe₂O₃ as nucleating agent were characterised by XRD, SEM (scanning electron microscope) and DTA (differential thermal analysis) techniques. Optical absorption, EPR, FTIR and Raman studies are also carried out on these glass ceramics. Absorption bands observed at about 457, 489, 678 and 820 nm are the characteristics of Fe³⁺ ions whereas the band observed at about 964 nm is due to Fe²⁺ ions. EPR studies suggested that Fe³⁺ ions entered in the lattice as tetragonally distorted octahedral symmetry or rhombic sites at low concentration of Fe₂O₃, whereas at higher concentration of Fe₂O₃ (beyond 1 mol%), the super exchange type of interactions between multivalency iron ions begin to dominate. FTIR and Raman spectra have revealed the behaviour of various structural units in the glass ceramic matrix. The analysis of these spectroscopic studies indicates that iron ions do exist in Fe³⁺ and Fe²⁺ state.     

掺Bi钨酸镉单晶体发光特性的研究

用坩埚下降法(Bridgman)生长出了Bi离子掺杂的CdWO₄单晶.测定了晶体不同部位的吸收光谱、发射光谱和X射线电子能谱(XPS).Bi离子的掺入引起CdWO₄晶体的吸收边从345 nm红移到399 nm.在311 nm, 373 nm,808 nm和980 nm光的激发下,分别观测到中心波长为470 nm,528 nm,1078 nm和较弱的1504 nm四个不同发射带.Bi:CdWO₄单晶的XPS谱分别与Bi₂ 关键词： Bi离子 荧光光谱 X射线电子能谱 4单晶')" href="#">CdWO₄单晶     

Enhanced photoluminescence of Sm/Bi co-doped Gd2O3 phosphors by combustion synthesis

Gd₂O₃:Sm³⁺ and Gd₂O₃:Sm³⁺,Bi³⁺ powders were prepared by a combustion method. Their structures were determined using X-ray diffraction. UV-visible absorption and photoluminescence spectra were investigated for Gd₂O₃:Sm³⁺ and Gd₂O₃:Sm³⁺,Bi³⁺ at different annealing temperatures and different doping concentrations. The emission spectra of all samples presented the characteristic emission narrow lines arising from the ⁴G_5/2→⁶H_J transitions (J=5/2, 7/2, and 9/2) of Sm³⁺ ions upon excitation with UV irradiation. The emission intensity of Sm³⁺ ions was largely enhanced with introducing Bi³⁺ ions into Gd₂O₃:Sm³⁺ and the maximum occurred at a Bi³⁺ concentration of 0.5 mol%. The relevant mechanisms were discussed with the sensitization theory by Dexter and the aggregation behavior of Bi³⁺ ions.     

Broadband infrared luminescence in Yb-doped Bi2O3–GeO2 glasses

The Yb-doped Bi₂O₃–GeO₂ glasses were prepared by the conventional melt quenching technique. Near-infrared (NIR) broadband emission was found at about 1024 nm, and 1330 nm (under 785 nm excitation), and the measured fluorescent lifetime was about several hundred microseconds. The emission intensity of Yb-doped Bi₂O₃–GeO₂ glasses increased with increasing of Yb dopant in our experiments. The NIR emission should be related to Yb³⁺ and lower valence Bi ions.     

The broadband NIR emission properties of Bi doped La2O3–Al2O3–SiO2 glass

Bi₂O₃ doped 65SiO₂–20Al₂O₃–15La₂O₃ (in mole%) glasses were prepared by the traditional melting–quenching method. The spectroscopic properties and mechanism of NIR broadband emission in these glasses were investigated in this work. Three excitation wavelengths of 500, 700 and 800 nm were used to test emission spectra. The emission band under 500 nm excitation can be regarded as combination of emission bands under 700 and 800 nm excitation. 2.0 mole% is found to be the optimal Bi₂O₃ doping level in this glass. Under 500 nm excitation its emission peak, FWHM and lifetime of emission band are 1160 nm, 300 nm and 569 μs, respectively. The longest fluorescent lifetime reaches 620 μs under 700 nm excitation. The valence state of Bi in these glasses is suggested to be lower than +3 by X-ray photoelectron spectroscopy. With the help of energy matching, we infer that both Bi⁰ and Bi⁺ centers are responsible for the NIR fluorescence of Bi₂O₃ doped 65SiO₂–20Al₂O₃–15La₂O₃ glass.     

Structural and optical properties of La and Gd substituted Bi4 − x M x V2O11 − δ (0.1 ≤ x ≤ 0.3)

Bi_4???x M _x V₂O_11???δ (M?=?La, Gd; 0.1?≤?x?≤?0.3) is synthesised by a solid state reaction method to study the effect of La³⁺ and Gd³⁺ substitution for Bi on the structural and optical properties. The as-prepared samples are characterised by X-ray diffraction, Fourier transform infrared analysis, UV–visible spectroscopy, scanning electron microscopy and energy-dispersive spectroscopy. The refinement results confirmed that even substituted samples exhibit monoclinic structure with space group C2/m. The parameters like band gap energy; Urbach energy has been calculated from the UV–visible spectra. It has been observed that even substitution at the bismuth site by isovalent cations decreases the energy band gap. The lowest observed band gap is 1.86 eV for Bi_3.9La_0.1V₂O_11???δ . The grain size and defects were observed to increase with increasing substitution along with the amount of secondary phase.     

Yb3+/Er3+共掺锗碲酸盐玻璃上转换发光增强机理的研究

玻璃的最大声子能量决定稀土离子的上转换发光强度，但本研究发现：Yb³⁺/Er ³⁺共掺锗碲酸盐玻璃在980nm LD抽运下，上转换荧光强度随着Bi₂O ₃对PbO的取代和碱 金属离子半径的增大而明显增强.而Raman光谱显示基质玻璃的最大声子能量并不随Bi ₂O₃对PbO的取代和碱金属离子半径的增大而变化，但玻璃的最大声子密 度随着Bi₂O₃对PbO 取代和碱金属离子半径的增大而降低.从玻璃无辐射跃迁概率的角度，通过分析表明，最大 声子密度的降低是玻璃上转换发光强度增强的主要原因.     

Er3+/Ce3+共掺碲铋酸盐玻璃的制备及光谱特性提高研究

采用高温熔融退火法制备了系列 80TeO₂-10Bi₂O₃-10TiO₂-0.5Er₂O₃-xCe₂O₃ (x=0,0.25, 0.5,0.75,1.0 mol%)和(80-y) TeO₂-10Bi₂O₃-10TiO₂-yWO₃-0.5Er₂O₃-0.75Ce₂O₃ (y=3,6,9,12 mol%)的碲铋酸盐玻璃.测试了玻璃样品400-1700 nm范围内的吸收光谱, 975 nm抽运下的上转换发光谱和1.53 μm波段荧光谱, 以及808 nm激励下的Er³⁺离子荧光寿命和无掺杂玻璃样品的Raman光谱, 并结合Judd-Ofelt理论和McCumber理论计算了Er³⁺离子光谱参数.结果表明, 在掺Er³⁺碲铋酸盐玻璃中引入Ce³⁺离子进行Er³⁺/Ce³⁺共掺, 通过Er³⁺离子⁴I_11/2能级与Ce³⁺离子²F_5/2 能级间基于声子辅助的能量传递过程,可以有效抑制Er³⁺离子上转换发光并明显增强其 1.53 μm波段荧光;同时,在现有Er³⁺/Ce³⁺共掺玻璃组分基础上引入WO₃, 可进一步提高1.53 μm波段荧光并展宽其荧光发射谱. 研究结果对于获取优异光谱特性的宽带掺Er³⁺光纤放大器玻璃基质具有实际意义.     

Mössbauer spectra and electrical conductivity ofxFe2O3−(40-x)V2O5−60P2O5 glasses

Mössbauer spectra and electrical conductivities were measured for the purpose of studying on the conduction mechanism of xFe₂O₃?(40-x)V₂O₅?60P₂O₅ glasses. The ratios Fe²⁺/Fe²⁺+Fe³⁺ in xFe₂O₃?(40-x)V₂O₅?60P₂O₅ glasses were determined by Mössbauer spectroscopy. On the composition dependence of D. C. conductivities in these glasses, the minimum of log σ at each temperature was obtained at 25Fe₂O₃?15V₂O₅?60P₂O₅. The conductivities of ternary glassses in Fe rich region could be explained only by the changes of carrler (Fe²⁺) concentration and the hopping conduction between Fe²⁺ ions and Fe³⁺ ions in binary glasses. In V rich region, the saturation tendency of D. C. conductivities are observed. It was suggested to be explained by increasing of V⁴⁺ ions due to the influence of Fe ions.     

Studies on the origins of the absorption spectra in PbWO4 crystal

The electronic structures and absorption spectra for both the perfect PbWO₄ (PWO) crystal and the three types of PWO crystals, containing V_Pb²⁻, V_O²⁺ and a pair of V_Pb²⁻-V_O²⁺, respectively, have been calculated using CASTEP codes with the lattice structure optimized. The calculated absorption spectra indicate that the perfect PWO crystal does not occur absorption band in the visible and near-ultraviolet region. The absorption spectra of the PWO crystal containing V_Pb²⁻ exhibit seven peaks located at 1.72 eV (720 nm), 2.16 eV (570 nm), 2.81 eV (440 nm), 3.01 eV (410 nm), 3.36 eV (365 nm), 3.70 eV (335 nm) and 4.0 eV (310 nm), respectively. The absorption spectra of the PWO crystal containing V_O²⁺ occur two peaks located at 370 nm and 420 nm. The PWO crystal containing a pair of V_Pb²⁻-V_O²⁺ does not occur absorption band in the visible and near-ultraviolet region. This leads to the conclusions that the 370 and 420 nm absorption bands are related to the existence of both V_Pb²⁻ and V_O²⁺ in the PWO crystal and the other absorption bands are related to the existence of the V_Pb²⁻ in the PWO crystal. The existence of the pair of V_Pb²⁻-V_O²⁺ has no visible effects on the optical properties. The calculated polarized optical properties are well consistent with the experimental results.     

Emission analysis of Dy and Pr:Bi2O3-ZnF2-B2O3-Li2O-Na2O glasses

In this paper, we present the spectral results of Dy³⁺ and Pr³⁺ (1.0 mol%) ions doped Bi₂O₃-ZnF₂-B₂O₃-Li₂O-Na₂O glasses. Measurements of X-ray diffraction (XRD), differential scanning calorimetry (DSC) profiles of these rare-earth ions doped glasses have been carried out. From the DSC thermograms, glass transition (T_g), crystallization (T_c) and melting (T_m) temperatures have been evaluated. The direct and indirect optical band gaps have been calculated based on the glasses UV absorption spectra. The emission spectrum of Dy³⁺:glass has shown two emission transitions ⁴F_7/2→⁶H_15/2 (482 nm) and ⁴F_7/2→⁶H_13/2 (576 nm) with an excitation at 390 nm wavelength and Pr³⁺:glass has shown a strong emission transition ¹D₂→³H₄ (610 nm) with an excitation at 445 nm. Upon exposure to UV radiation, Dy³⁺ and Pr³⁺ glasses have shown bright yellow and reddish colors, respectively, from their surfaces.