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.     

UV-visible and infrared absorption spectroscopic studies of gamma irradiated tungsten-doped lithium phosphate glasses

Ultraviolet-visible and infrared spectroscopic techniques were employed to investigate the undoped lithium phosphate glass and other samples of the same composition doped with varying WO₃ contents. The same spectroscopic properties were remeasured after subjecting the samples to 3 and 6 Mrad doses of gamma irradiation on the measured properties. Such combined analytical techniques are expected to give information about the state of tungsten ions in such lithium phosphate glass and justify the effect of gamma irradiation. The work aims to deduce the radiation-induced defects generated through successive gamma irradiation by optical measurements. Also, the study is expected to realize through IR spectroscopy, the main structural building groups and the influence of tungsten ions within the structural vibrational groups of the studied 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.     

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.     

Optical properties of vanadium-doped bismuth borate glasses before and after gamma-ray irradiation

UV–visible, infrared and Raman spectra, together with thermal properties, were measured for glasses from the system Bi₂O₃–B₂O₃–V₂O₅ before and after successive gamma irradiations. The UV–visible spectrum of the undoped glass before irradiation reveals five UV bands at 210, 275, 310, 350 nm, an intense band at 380 nm and a visible band at 420 nm due to the possible combined presence of trace iron impurities and Bi³⁺ ions. The V-doped glasses reveal six UV bands and two visible bands, probably arising from vanadium ions in three possible valencies, V³⁺, V⁴⁺ and V⁵⁺, beside that due to trace iron impurity beside Bi³⁺ ions. The spectra reveal an obvious resistance of the glasses to successive gamma irradiation. The Raman and infrared spectra show characteristic absorption bands, which indicate the sharing of Bi³⁺ ions as glass-forming (BiO₆) octahedral units together with the presence of various groups of the borate network.     

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.     

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.     

Physical and Optical Properties of Calcium Zinc Borophosphate Glasses Doped with Manganese Ions

This article reports on the physical and optical properties, absorption, and luminescence spectra in the visible region, of calcium zinc borophosphate glasses doped with manganese ions. The manganese composition was varied up to 10 mol%. The aim of this work was to investigate the effect of the luminescence properties when the glasses were doped with different compositions of manganese ions. X-ray diffraction profiles confirmed their glassy nature. The optical absorption spectrum showed bands characteristic of manganese ions in octahedral symmetry. Both excitation and emission spectra were recorded for these glasses to understand their optical performances. The emission spectrum showed a single broad band (green region) in octahedral symmetry at 582 nm as a result of transition from the upper ⁴T_1g state to the ⁶A_1g ground state of manganese ions. As the concentration of manganese ions increased, the emission band increased from 582 nm (green-light emission) to 650 nm (red-light emission). Apart from the spectral analysis, different physical properties of these glasses were also analyzed. Based on the physical and optical properties, we found the samples to be more promising for their use as novel luminescent optical materials.     

Ion transport studies in zinc/cadmium halide doped silver phosphate glasses

A number of samples of silver phosphate glasses Ag₂O−P₂O₅−Zn/CdX₂ (X=Cl, Br or I) with 1, 5, 10 and 20 mol-% zinc or cadmium halides have been prepared. Control samples of undoped silver phosphate glasses were also prepared. These glasses were characterized by elemental analysis, X-ray diffraction, IR spectra, differential scanning calorimetry, transference number measurements and electrical conductivity studies. These glasses were found to be essentially ionic conductors. The undoped silver phosphate glass (Ag₂O−P₂O₅) has a low σ value in comparison to the doped ones. The conductivity (σ) in the doped glasses increases substantially with increasing concentration of dopant salts Zn/or CdX₂ and as the anions of the dopants are changed from Cl⁻ to I⁻. It is found that the σ values of the ZnX₂ doped glasses are slightly greater than those of the CdX₂ doped ones, and the silver phosphate glasses doped with (20 mol-%) Zn/CdI₂ yielded maximum conductivity. The results have been discussed and explained on the basis of changes in the structure of the glass matrix by the addition of dopant ions of different sizes, IR spectra and thermal studies.     

Luminescence studies on ZnO-P2O5 glasses doped with Gd2O3:Eu nanoparticles and Eu2O3

Zinc phosphate glasses doped with Gd₂O₃:Eu nanoparticles and Eu₂O₃ were prepared by conventional melt-quench method and characterized for their luminescence properties. Binary ZnO-P₂O₅ glass is characterized by an intrinsic defect centre emission around 324 nm. Strong energy transfer from these defect centres to Eu³⁺ ions has been observed when Eu₂O₃ is incorporated in ZnO-P₂O₅ glasses. Lack of energy transfer from these defect centres to Eu³⁺ in Gd₂O₃:Eu nanoparticles doped ZnO-P₂O₅ glass has been attributed to effective shielding of Eu³⁺ ions from the luminescence centre by Gd-O-P type of linkages, leading to an increased distance between the luminescent centre and Eu³⁺ ions. Both doped and undoped glasses have the same glass transition temperature, suggesting that the phosphate network is not significantly affected by the Gd₂O₃:Eu nanoparticles or Eu₂O₃ incorporation.     

Sensitized fluorescence of Ce3+/Mn2+ system in phosphate glass

The preparation of sodium phosphate glasses singly and doubly doped with rare earth ion Ce³⁺ and transition metal ion Mn²⁺ by a melt quench method is described. The spectroscopic characterizations of the samples are conducted by absorption, excitation, and emission spectra. The orange red emission of divalent manganese sensitized by trivalent cerium ions in a phosphate glassy matrix has been investigated. Energy transfer (ET) from optically excited Ce³⁺ to Mn²⁺ in sodium phosphate glass, by nonradiative process is confirmed by fluorescence studies with various activator concentrations. The mechanism of ET is mainly electric dipole–dipole in nature.     

EPR study of the impurity paramagnetic centres in (CaO−Ga2O3−GeO2) glasses

The X-band EPR spectra of Cr³⁺, Mn²⁺, and Fe³⁺ impurity ions in glasses of (CaO?Ga₂O₃?GeO₂) system are investigated in the 77÷300 K temperature range. The experimental data analysis yields the following results: (i) Impurity chromium ions are incorporated into the (CaO?Ga₂O₃?GeO₂) glasses network in Cr³⁺ (3d³,⁴F_3/2) paramagnetic valence state only and occupy the strong distorted oxygen coordinated octahedral sites. (ii) For all activated and non-activated (CaO?Ga₂O₃?GeO₂) glasses the iron impurity is present at concentration roughly 0.01 wt.%. Isotropic EPR signals atg _eff=4.29 andg _eff=2.00 are assigned to Fe³⁺ (3d⁵,⁶S_5/2) ions in the sites with strong rhombic distortion and in the sites with nearly cubic symmetry respectively. (iii) The manganese EPR spectrum in (CaO?Ga₂O₃?GeO₂) glasses is weakly dependent on temperature, doping procedure as well as manganese concentration. EPR spectra of impurity manganese ions in glasses with Ca₃Ga₂Ge₃O₁₂ and Ca₃Ga₂Ge₄O₁₄ compositions are virtually identical and belong to Mn²⁺ (3d⁵,⁶S_5/2) ions. Impurity manganese ions are incorporated into the (CaO?Ga₂O₃?GeO₂) glass network as isolated Mn²⁺ centres and clusters of Mn²⁺ ions.     

Response of commercial window glass to gamma doses

This work reports experimental results of an effort undertaken to identify and characterize the radiation-induced defects created during gamma (γ)-irradiation of commercial glass on the basis of optical absorption measurements performed before and after irradiation. It is assumed that the induced absorption band formed after γ-irradiation of soda-lime-silica (SLS) glasses are created by some hole-type color centers related with non-bridging oxygen ions (NBO⁻) located in different surroundings.Results have been discussed taking into consideration the presence of iron as impurity in the glass structure. It is well known that the absorption bands of Fe³⁺ in the visible range is at 420-440 nm, in this study the band at 430 nm was followed. Also, the optical gap variations (ΔE_opt) induced by γ-irradiation were investigated.Moreover, the study illustrated that the optical absorption sensitivity and the mechanism of fading either at room or elevated temperature has been discussed in relation to successive irradiation doses, dose rate and thickness. The results are discussed on the basis of the annihilation mechanisms of induced irradiation defects.     

Mössbauer, X-ray, electrical and magnetic properties of lithium borosilicate glasses containing iron and manganese Part I. Mössbauer measurements

The effect of the replacement of MnO₂ by Fe₂O₃ on the oxidation states of iron in some lithium borosilicate glasses were studied using Mössbauer spectroscopy. DTA and infrared measurements showed the presence of two glassy phases, one of them containing iron and the other manganese. The Mössbauer spectra were measured at room temperature for all the glass samples. The spectra revealed the presence of Fe ions only in ferric state in both tetrahedral and octahedral coordination. Also, it was observed that the ratio between the number of iron ions in both coordination states has not changed with the increase of MnO₂ content.     

The valence states of manganese ion in potassium-borate oxide glasses

EPR and magnetic susceptibility measurements have been performed on xMnO·(1-x) [2B₂O₃·K₂O] with 0?x?50 mol %. The X-ray diffraction analysis showed that in this glass system homogeneous glasses are formed up to x = 70 mol %.EPR and magnetic susceptibility data have shown that in the glasses with x ? 5 mol % only Mn²⁺ ions are present as magnetically isolated species. EPR spectra are modified with the increasing of manganese ions content. In the concentration range 0.5 ? x ? 5 mol %, the spectra are characterized by appearance of three resonance absorptions at g ? 4.3 and g ? 3.3 without hyperfine structure, and at g ? 2.0 with hyperfine structure. For the glasses with x >62; 5 mol %, the resonance spectra are characterized by the appearance of the broad line at g ? 2, characteristic for clustered ions. The magnetic susceptibility data suggest the appearance of superexchange interactions for x >62; 5 mol %. From Curie constant values and qualitative chemical analysis we have established that in the glasses with x ? 10 mol % both, Mn²⁺ and Mn³⁺ ions are present.     

Bismuth silicate glass containing heavy metal oxide as a promising radiation shielding material

Optical and FTIR spectroscopic measurements and electron paramagnetic resonance (EPR) properties have been utilized to investigate and characterize the given compositions of binary bismuth silicate glasses. In this work, it is aimed to study the possibility of using the prepared bismuth silicate glasses as a good shielding material for γ-rays in which adding bismuth oxide to silicate glasses causes distinguish increase in its density by an order of magnitude ranging from one to two more than mono divalent oxides. The good thermal stability and high density of the bismuth-based silicate glass encourage many studies to be undertaken to understand its radiation shielding efficiency. For this purpose a glass containing 20% bismuth oxide and 80% SiO₂ was prepared using the melting–annealing technique. In addition the effects of adding some alkali heavy metal oxides to this glass, such as PbO, BaO or SrO, were also studied. EPR measurements show that the prepared glasses have good stability when exposed to γ-irradiation. The changes in the FTIR spectra due to the presence of metal oxides were referred to the different housing positions and physical properties of the respective divalent Sr²⁺, Ba²⁺ and Pb²⁺ ions. Calculations of optical band gap energies were presented for some selected glasses from the UV data to support the probability of using these glasses as a gamma radiation shielding material. The results showed stability of both optical and magnetic spectra of the studied glasses toward gamma irradiation, which validates their irradiation shielding behavior and suitability as the radiation shielding candidate materials.     

Radiation induced paramagnetic centres in MgOAl2O3SiO2 glasses containing TiO2

Upon irradiation with ⁶⁰Co γ-rays Cordierite glasses with added TiO₂ display two dominant ESR resonances arising from (a) Ti³⁺ ions (b) holes trapped at non-bridging oxygen ions singly bonded to [SiO₄]^? tetrahedra. The Ti³⁺ ions appear to be in D_4h octahedral sites with the evident distributions between the principal g values arising from an isotropic randomness at the titanium sites. However, the g parameter distributions of the hole resonance, and their changes during the addition of TiO₂ indicate the development of Silicate structures in the glasses which are the precursors of the major low temperature crystalline phases. The invariance of the hole and electron resonance lines with pre-crystallization heat treatments indicates that neither the titanium associated structures or the basic silicate structure of the glass are changed by such treatments.     

Effect of gamma irradiation on X‐ray absorption and photoelectron spectroscopy of Nd‐doped phosphate glass

X‐ray absorption near‐edge structure (XANES) and X‐ray photoelectron spectroscopy (XPS) of Nd‐doped phosphate glasses have been studied before and after gamma irradiation. The intensity and the location of the white line peak of the L₃‐edge XANES of Nd are found to be dependent on the ratio O/Nd in the glass matrix. Gamma irradiation changes the elemental concentration of atoms in the glass matrix, which affects the peak intensity of the white line due to changes in the covalence of the chemical bonds with Nd atoms in the glass (structural changes). Sharpening of the Nd 3d_5/2 peak profile in XPS spectra indicates a deficiency of oxygen in the glasses after gamma irradiation, which is supported by energy‐dispersive X‐ray spectroscopy measurements. The ratio of non‐bridging oxygen to total oxygen in the glass after gamma radiation has been found to be correlated to the concentration of defects in the glass samples, which are responsible for its radiation resistance as well as for its coloration.     

Spectroscopic properties of Mn2+ in new bismuth and lead contained fluorophosphate glasses

Luminescence, absorption and electron spin resonance (ESR) spectroscopic measurements are performed for two new Mn²⁺ doped fluorophosphate glass systems containing bismuth and lead, respectively, i.e., 45Ba(PO₃)₂-55BiF₃ and 45Ba(PO₃)₂-55PbF₂, to elucidate the nature of dopant–ligand bonding in terms of the covalence degree of dopant–ligand bond and ligand field strength. It is found from luminescence measurements that an octahedral coordination of dopant is formed, which is the same as that in fluoroberyllate and phosphate glasses. The optical absorption measurements indicate that the position of the absorption band, ⁴T_1g(G), is red shifted, and the Racah coefficient B is 625 and 627 cm^-1, respectively, as ligand field strength increases in the order of fluoroberyllate, fluorophosphate, phosphate and silicate glasses. The hfs constant A determined from the ESR measurements is 94.33 and 92.12 Oe for two glass systems, respectively. The hfs constant A is also found to be 89.98 Oe and 94.33 Oe in the respective crystalline and glasses 45P₂O₅-55BiF₃. In addition, the resonance observed at g2 in both glass systems is mainly attributed to Mn²⁺ ions in an environment close to octahedral symmetry distorted by agglomeration of resonant centers. It, thus, can be concluded from the ESR measurements that the degree of covalency of dopant–ligand bond in both fluoroberyllate and phosphate glasses is similar, and the crystallization of the glass leads to an increase in the degree of covalency of the ligand–Mn²⁺ bond. PACS 42.70.Ce; 61.43.Fs; 78.55.Qr     

Optical and other spectroscopic studies of lead, zinc bismuth borate glasses doped with CuO

10MO·20Bi₂O₃·(70−x)B₂O₃·xCuO [M=Pb, Zn] with x=0, 0.4 and 0.8 (wt%) glasses were synthesized by the melt-quenching technique and were characterized using X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques. Physical parameters, like density, and spectroscopic studies (optical absorption, EPR, FTIR and photoluminescence) were used to understand the role of modifier oxide and CuO in the glass matrix. A red shift of the absorption band corresponds to ²B_1g→²B_2g transition of Cu²⁺ ions from P2 to Z4 samples and the increase of hyperfine splitting factor (A_‖) from P2 to Z2 shows that with the integration of PbO by ZnO the electron density around copper ion is increased. It is also supported by the gradual increase in theoretical optical basicity values of ZnO mixed glasses, as compared to that of PbO mixed glass matrix. Reduced bismuth radicals are found in undoped and 0.4% CuO doped glasses of both the series. Analysis of the absorption and emission studies indicates that the concentration of luminescence centers of bismuth ions (Bi³⁺ ions in UV region) is decreased by the integration of ZnO as well as by increasing the dopant concentration. In lead series PbO₄ and BiO₃ units are increased from P2 to P4 and in zinc series BiO₃ units are decreased from Z0 to Z4. The conductivity of the glass matrices is increased in both the series with the dopant of CuO.